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Tesi sul tema "Annealing. microstructure"
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1
Thomas, Richard. "Microstructure development in multicomponent alloys." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242037.
Testo completo
2
Ohlsson, Richard. "Variations in hardness and microstructure in cartridge cases at annealing." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68670.
Testo completoAbstract (sommario):
The thesis work is performed at Norma Precision AB, a company that manufactures ammunition for hunting and competitive shooting. Two types of cases called 300 Winchester Magnum and 308 Winchester are examined on how their hardness were prior to and after the two annealing’s of the neck they experience during the manufacturing. The cases vary in hardness and an investigation will be made to draw connections to the microstructure of the cases in order to understand the variations and possibly avoid the variations in the future. The cases were selected at different days, the 300 Winchester Magnum were chosen at three different days with some properties varying and the 308 Winchester were taken at two different days. At each day twenty cases were selected, five prior to the first neck annealing, five after the first neck annealing, five after the shaping and calibrating of the cases and the final five after the second neck annealing. The selected cases were first measured by a hardness test, where they were measured at 1mm, 3mm and 6mm from the nuzzle and five times around the case at each measurement. After that, the variations were analyzed and the two most varying cases from each day and step were taken into the laboratory at Karlstad University. In the laboratory, the cases were measured by a microhardness tester. The cases were measured at even distances between them all throughout the cases to make a hardness profile. The next step was to etch the cases and examine them in an optical microscope, where the grain size was measured in micrometer and ASTM. The results from the regular hardness measurements and the microhardness tests showed similar tendencies. Variations was found in each step and each day during both hardness measurements the two types of cases behaved similarly. The grain size results showed that after annealing, the grain size increased. Although there was no clear relation between grain size and hardness since the results varied, some cases with higher hardness had a smaller grain size than a case with lower hardness. Using the grain size of the brass could work to get an idea of the hardness, but to get a sincerer perception of the material properties, more properties needs to be investigated.<br>Examensarbetet är utfört hos Norma Precision, ett företag som tillverkar ammunition för viltjakt och för tävlingsskytte. Två sorters hylsor vid namn 300 Winchester Magnum samt 308 Winchester undersöks hur deras hårdhet är innan respektive efter de två mynningsglödgningar hylsorna genomgår under tillverkningen. Hylsorna varierar i hårdhet och en undersökning kommer göras för att dra kopplingar till hylsornas mikrostruktur för att få en förståelse av variationerna och eventuellt kunna undvika variationer i framtiden. Hylsorna valdes ut vid olika dagar, 300 Winchester Magnum togs vid tre olika tillfällen när olika egenskaper skiljde och 308 Winchester togs vid två tillfällen. Varje dag plockades tjugo hylsor ut, fem innan första mynningsglödgningen, fem efter den första mynningsglödgningen, fem efter formning och kalibrering av hylsorna samt fem efter den andra mynningsglödgningen. På de utplockade hylsorna gjordes först hårdhetstester, då de mättes vid 1mm, 3mm och 6mm ifrån mynningen och fem mätningar runt hylsan vid varje mättillfälle. Efter det analyserades resultaten och de två hylsor som varierade mest från varje dag och varje steg togs med till labbet på Karlstads Universitet. I labbet mättes hylsorna med en mikrohårdhetsmätare. Hylsorna mättes med jämna mellanrum genom hela hylsan för att skapa en hårdhetsprofil. Nästa steg var sedan att etsa hylsorna och undersöka dem i ett ljusmikroskop, där mätningar av kornstorlek i mikrometer och ASTM gjordes. Resultaten från den vanliga hårdhetsmätningen och från mikrohårdhetsmätningen visade liknande tendenser. Det upptäckes variationer i varje steg och varje dag i båda hårdhetsmätningarna och de två sorternas hylsor betedde sig likadant. Resultaten från kornstorleksmätningarna visade att efter glödgning ökade kornstorleken. Det fanns dock inget tydligt mellan kornstorlek och hårdhet då resultaten varierade, i vissa fall hade hylsorna med högre hårdhet en mindre kornstorlek än hylsor med lägre hårdhet. Att använda mässingens kornstorlek kan fungera för att få en övergripande bild av hårdheten, men för att få en bättre förståelse av materialegenskaperna behöver fler egenskaper undersökas.
3
Kulakov, Mykola. "Microstructure evolution during intercritical annealing of a Mn-Cr dual-phase steel." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44695.
Testo completoAbstract (sommario):
A model was developed to describe the microstructure evolution during intercritical annealing of a low-carbon steel suitable for industrial production of dual-phase steels (DP600 grade) on a hot-dip galvanizing line. The microstructure evolution model consists of individual submodels for recrystallization, austenite formation in a fully recrystallized material and austenite decomposition after partial austenization. These submodels were developed using the Johnson-Mehl-Avrami-Kolmogorov approach and the additivity principle. The model parameters were obtained based on the results of systematic experiments addressing the effects of initial microstructures and processing conditions on the microstructure evolution in the course of intercritical annealing. The initial microstructures included 50 pct cold-rolled ferrite-pearlite, ferrite-bainite-pearlite and martensite. If heating to an intercritical temperature was sufficiently slow, recrystallization was completed before austenite formation, otherwise austenite formed in a partially recrystallized microstructure. The recrystallization-austenite formation interaction accelerated austenization in all three starting microstructures by providing additional nucleation sites and enhancing growth rates; this complex process could not be accounted for with the current modelling approach. A variety of austenite morphologies was produced by using different initial microstructures and/or by means of the interaction of recrystallization and austenite formation. Following the complete intercritical annealing cycle, the final microstructure was composed of ferrite, bainite and martensite; the latter two components inherited the distribution and morphology of those for intercritical austenite. The microstructure evolution model was validated using simulated industrial thermal paths for intercritical annealing. Laser ultrasonics was employed for in-situ monitoring of phase transformations to facilitate the validation of the microstructure evolution model.
4
Miszczyk, Magdalena Maria. "Microstructure and texture evolution during annealing of plane strain compressed fcc metals." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-00904405.
Testo completoAbstract (sommario):
The present research program is a renewed attempt at explaining the transformation mechanisms. The experimental investigations has focused on a model analysis of transformations which occur in single crystals, with stable orientations, i.e. Goss{110}<001> and brass{110}<112>, the deformation is carried out by channel-die compression to simulate the rolling process of thin sheets. Next, the samples were annealed at temperatures of primary recrystallization. The analysis of crystallographic transformations was conducted on metals from a wide spectrum of stacking fault energy: low - Cu-2%Al, average- Cu and Ni to high Al and Al-1%Mn. At work were analyzed the mechanisms controlling the initial stages of recrystallization. Detailed analysis of disorientation across the recrystallization front clearly showed that the initial grain orientations were not accidental. The axes of disorientation in the relationship across the front of recrystallization were near normal in {111} planes, but only sporadically covered with the <111> direction. The distribution of the recrystallization angle rotation in relation to the preferences presented through the formation of two maxima values near 30 ° and 45-55 °.
5
Zhu, Benqiang. "Phase-field modeling of microstructure evolution in low-carbon steels during intercritical annealing." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52176.
Testo completoAbstract (sommario):
Intercritical annealing is used widely in the steel industry to produce advanced high strength steels for automotive applications, e.g. dual-phase steels. A phase-field model is develop to describe microstructure evolution during intercritical annealing of low-carbon steels. The phase-field model consists of individual sub-models for ferrite recrystallization, austenite formation and austenite to ferrite transformation. In particular, a Gibbs-energy dissipation model is coupled to the phase-field model to describe the effects of solutes on migration of austenite/ferrite interfaces. The model is applied to a low-carbon steel with a cold-rolled pearlite/ferrite microstructure suitable for industrial production of dual-phase steels (DP600 grade). The sub-model parameters, e.g. nucleation parameters and interface mobilities, are tuned using experimental data. The interaction of concurrent ferrite recrystallization and austenite formation is investigated using the developed model. The simulation results reveal that ferrite recrystallization can be inhibited by the pinning effect of austenite particles and concurrent ferrite recrystallization can lead to intragranular distribution of austenite in the final microstructure. The transition of austenite morphology from a network structure to a banded structure with increasing heating rates is replicated by the phase-field model. The model is validated using a simulated industrial intercritical-annealing cycle. Moreover, the developed phase-field model is used to describe cyclic phase transformations in the intercritical region for a plain-carbon steel and a manganese-alloyed low-carbon steel. The consideration of Gibbs-energy dissipation in the phase-field model rationalizes the existence of stagnant stages during cyclic phase transformations in the manganese-alloyed low-carbon steel. In summary, the developed model provides a single tool that is able to describe various physical phenomena occurring in an entire intercritical-annealing cycle. Phase-field modeling can be a promising approach for developing process models for advanced steels in the future.<br>Applied Science, Faculty of<br>Materials Engineering, Department of<br>Graduate
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Cusick, Michael Christopher. "THE USE OF SELECTIVE ANNEALING FOR SUPERPLASTIC FORMING OF MG AZ31 ALLOY." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/492.
Testo completoAbstract (sommario):
A recent study on the Post-Formed properties of Superplastically Formed Magnesium AZ31B has shown that the heating time prior to testing has a major effect on the Post Forming properties of the superplastically material. To this point, there has been very little examination into the effect of pre-heating or annealing on superplastic forming (SPF) properties. In this work, the effects of annealing prior to the SPF of Mg AZ31 alloy were examined. Both high temperature SPF tensile and bulge specimens were formed after annealing. Multiple annealing temperatures were examined to produce specimens with grain sizes ranging from 8 andamp;igrave;m to 15 andamp;igrave;m for comparison with traditional SPF results. The results show that the effect of annealing can be suitable for the improvement of thinning and possibly the forming time of superplastically formed Magnesium alloys through the control of the microstructure.
7
Xu, Wanqiang Materials Science & Engineering Faculty of Science UNSW. "Effect of initial microstructure on the deformation and annealing behaviour of low carbon steel." Awarded by:University of New South Wales. School of Materials Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/26801.
Testo completoAbstract (sommario):
The effect of initial microstructures of an 0.05 wt.% C low carbon steel, acicular ferrite (AF), Bainite (B), polygonal ferrite (PF), fine polygonal ferrite (FPF), and a microstructure produced by direct strip casting (DSC) (termed SC), on the deformation and recrystallization behaviour of cold rolled low carbon (LC) steel, was investigated. The initially prepared samples with the initial microstructures were cold rolled to 50, 70 and 90% reductions, then annealed isothermally in the temperature range 580 ??? 680 oC. The microstructures and textures produced by deformation and annealing were studied by optical microscopy, XRD, TEM, SEM and EBSD. The initial microstructures were characterized mainly by optical microscopy and EBSD. Using EBSD, the ferrite grain size of the AF, B and SC samples was considerably larger than that found by optical microscopy with a large fraction of low angle grain boundaries (LAGBs) observed within prior austenite grains. All samples exhibited a very weak texture close to random. After cold rolling, the microstructures of AF and SC contained shear bands with PF and FPF generating deformation bands. For AF and SC, the pearlite phase was more extensively elongated in rolling direction compared with PF and FPF. After 90% cold rolling reduction, PF, FPF and SC consist mainly of the texture component and AF and B . It was found that FPF recrystallized most rapidly followed by B, PF and AF with SC recrystallizing orders of magnitude more slowly due to the solution drag caused by its uniformly distributed higher Mn content. Very strong (???-fibre) texture was generated in cold rolled PF followed by FPF, with AF, SC and B generating very weak textures. The texture evolution during annealing 90% reduction PF was examined in further detail. The behaviour of nucleation and grain growth provides strong evidence of orientated nucleation as the dominant factor for CRA texture development in this material.
8
Longanecker, Melanie J. "CONTROLLING THE MICROSTRUCTURE AND KINETICS OF BLOCK COPOLYMER SELF-ASSEMBLY BY DIRECT IMMERSION ANNEALING." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1509902596608426.
Testo completo
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Al-Buhamad, Oday Hatim Materials Science & Engineering Faculty of Science UNSW. "Accumulative roll bonding of multilayered aluminium alloys." Awarded by:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44806.
Testo completoAbstract (sommario):
Multilayered aluminium alloy composites were produced by accumulative roll bonding (ARB) to very high strain to generate sheet materials consisting of either 32 or 64 alternating layers of Al and Al-0.3w.%Sc alloy. Based on the starting heat treatment condition of the Al(Sc) alloy and the roll bonding temperature, several different Al/Al(Sc) combinations were produced: (i) SSSS-ARB (Al(Sc) in the supersaturated condition; Tdef = 200 ???C; 32 layers); (ii) Aged-ARB (Al(Sc) in the artificially aged condition; Tdef = 200 ???C; 32 layers), and (iii) SSSS-ARB-HT (Al(Sc) in the SSSS condition; Tdef = 350 ???C; 64 layers). Regardless of the roll bonding conditions, Al(Sc) in the form of a dispersion of ultrafine Al3Sc particles strongly impedes structural changes during thermomechanical processing whereas Al readily undergoes extensive dynamic and static restoration. The major aim of the thesis is to understand the effect of initial microstructure and processing conditions on microstructural development in these multilayered Al/Al(Sc) composites. The microstructures were investigated mainly by backscatter electron (BSE) and ion channeling contrast (ICC) imaging in the DualBeam Platform and transmission electron microscopy (TEM) whereas the crystallographic nature of the microstructures were investigated by electron backscatter diffraction (EBSD) and the various diffraction techniques available in the TEM. The mechanical properties of the materials were investigated by hardness and tensile testing. The deformation microstructure and texture of these two alloy combinations were strongly influenced by both the initial heat treatment condition of the Al(Sc) alloy whereby large-scale shear bands are generated during rolling when a dispersion of fine Al3Sc particles is present in the Al(Sc) layers. The deformation mechanism of both SSSS-ARB and Aged-ARB was strongly controlled by the relative hardening behaviour of adjacent layers. In Aged-ARB, a higher magnitude of in-plane shear stress, exceeding the flow stress of Al(Sc), was operative at the interfaces between layers; this was shown to cause the shear banding in this material. All materials were annealed for up to 6h at 350 ??C. This extended annealing generated alternating layers of coarse grains (Al layers) and a recovered substructure (Al(Sc) layers) with the substantial waviness of the layers in both Aged-ARB and SSSS-ARB-HT being inherited from the as-deformed material. While the Al(Sc) layers remain unrecrystallized in all materials due to particle pinning effects, the Al layers underwent continuous and discontinuous recrystallization after low and high temperature roll bonding, respectively. Shear banding in Aged-ARB also resulted in a reduction in intensity of the rolling texture components and had a randomizing effect on the recrystallization texture of the Al layers. The Al/A(Sc) multilayered composites were found to conform to the classic inverse strength/ductility relationship and no significant improvement in ductility (for a given strength) was evident. The barriers to achieving an excellent combination of ductility and strength (i.e. toughness) in these materials were identified to be delamination of the layers, which can be largely reduced (or eliminated) by careful control of starting materials (heat treatment condition and thickness) as well as the processing parameters during ARB.
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Porter, S. L. "Microstructure-mechanical property relationships during the thermomechnaical simulation and annealing of novel interstitial free steels." Thesis, Swansea University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638555.
Testo completoAbstract (sommario):
Interstitial Free (IF) Steels are widely used in the automotive industry. Their excellent mechanical property characteristics, such as the high formability typified by high r<sub>mean</sub>-values, low yield strength and high elongation make them very suitable for manufacturing into automotive body panels. However, their properties and microstructures are affected by their composition and processing conditions. This research program is focused on the optimisation of the properties of two Interstitial Free Steel Grades, an experimentally produced mild Ti-Nb IF Grade and a commercially produced high strength Ti-IF grade. The optimisation of the processing conditions is vital to the enhancement of obtained properties and is investigated in two parts within this research program. The first part will simulate the effect of variable hot rolling parameters on these two grades. This study will aim to investigate the effect of the finishing temperature, effect of run-out table cooling and coiling temperature, all of which are extremely important parameters within the hot mill and may have a significant effect on the microstructure and properties of the two grades. For this work the Gleeble 3500 thermomechanical system has been employed to simulate the hot rolling conditions. The second part will aim to simulate the effect of batch annealing sequences on cold rolled strips of these two grades. This shall aim to determine the optimum annealing conditions to obtain desirable properties on the studied grades. The work demonstrated the differences in microstructure and properties of the two grades investigated, with respect to the simulated processing parameters. It could be observed that the microstructures obtained on these two grades were indeed very different, with the microstructure of the high strength commercial Ti-IF grade consisting of mainly non-equilibrium ferritic and / or bainitic structures, while the microstructure of the mild experimental Ti-Nb IF Grade mainly consisting of recrystallised equiaxed ferrite. Testing of the batch annealed strips, revealed that the r<sub>mean</sub> -values were very high for both steels, thus permitting a determination of the annealing temperature for which optimum strength and formability values could be obtained.
11
Nabach, William A. "The effects of isothermal deformation and annealing on the microstructure of nickel-aluminum-bronze propeller material." Thesis, Monterey, Calif. : Naval Postgraduate School, 2003. http://bosun.nps.edu/uhtbin/hyperion.exe/03Jun%5FNabach.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, Terry R. McNelley.<br>Thesis Advisor(s): Terry R. McNelley. "June 2003." Includes bibliographical references (p. 41-43). Also available in print.
12
Shukla, Keerti. "The effect of annealing on the microstructure of Cu-Al-Ni-Mn shape memory alloy microwires." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100889.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 37-38).<br>Shape memory alloys exhibit superelasticity and the shape memory effect by undergoing a diffusionless phase transformation between the austenite and martensite phases. Nickel-titanium alloys are currently the most common material used. However, due to their expensive cost, alternatives such as Cu-based alloys have been investigated. Cu-based alloys have exhibited the shape memory effect and have achieved 6-8% strain recovery. This work investigates Cu-Al-Ni- Mn shape memory alloys in the form of microwires with the potential application in smart textiles. Wire microstructure and composition, transition temperatures, and strain recovery were analyzed after the wires were subjected to varying annealing times and temperatures. These data were used to determine the ideal conditions to achieve the most shape memory and superelasticity.<br>by Keerti Shukla.<br>S.B.
13
Cousins, Michael Andrew. "Microstructure of absorber layers in CdTe/Cds solar cells." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/4266/.
Testo completoAbstract (sommario):
This work concerns the microstructure of CSS-grown CdTe layers used for CdTe/CdS solar cells. Particular attention is given to how the development of microstructure on annealing with CdCl(_2) may correlate with increases in efficiency. By annealing pressed pellets of bulk CdTe powder, it is shown that microstructural change does occur on heating the material, enhanced by the inclusion of CdCl(_2) flux. However, the temperature required to cause significant effects is demonstrated to be higher than that at which heavy oxidation takes place. The dynamics of this oxidation are also examined. To investigate microstructural evolution in thin-films of CdTe, bi-layers of CdTe and CdS are examined by bevelling, thus revealing the microstructure to within ~1 µm of the interface. This allows optical microscopy and subsequent image analysis of grain structure. The work shows that the grain- size, which is well described by the Rayleigh distribution, varies linearly throughout the layer, but is invariant under CdCl(_2) treatment. Electrical measurements on these bi-layers, however, showed increased efficiency, as is widely reported. This demonstrates that the efficiency of these devices is not dictated by the bulk microstructure. Further, the region within 1 µm of the interface, of similar bi-layers to above, is examined by plan-view TEM. This reveals five-fold grain-growth on CdCl(_2) treatment. Moreover, these grains show a considerably smaller grain size than expected from extrapolating the linear trend in the bulk. These observations are explained in terms of the pinning of the CdTe grain size to the underlying CdS, and the small grain size this causes. A simple model was proposed for a link between the grain-growth to the efficiency improvement. The study also examines the behaviour of defects within grains upon CdCl(_2) treatment provided the first direct evidence of recovery on CdCl(_2) treatment in this system. Finally, a computer model is presented to describe the evolution of microstructure during growth. This is shown to be capable of reproducing the observed variation in grain size, but its strict physical accuracy is questioned.
14
Low, Thaddeus Song En. "Investigating the Stability of the α/ω Dual Phase Microstructure in Shock Impacted Zr". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524178270425181.
Testo completo
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Alshammari, Ohud. "EFFECT OF ANNEALING ON THE MICROSTRUCTURE AND MAGNETIC PROPERITES OF SELECTED (Ni-Mn-Ga) MELT-SPUN RIBBONS." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1464184585.
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Ye, Changhuai. "Microstructure Alignment and Mechanical Properties of Block Copolymer and Crystalline Polymer Thin Films." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1475553221643627.
Testo completo
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Iversen, Jørgen Tandberg. "Implementation and Testing of Numerical Models for Evolution of Microchemistry and Microstructure During Back-Annealing of Aluminium Alloys." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26682.
Testo completoAbstract (sommario):
Precipal and Alsoft are two separate models for simulating the effects of back-annealing on microchemistry and microstructure, respectively, in AA3xxx-type aluminium alloys (i.e Mn containing alloys). The precipitation model simulates the precipitation and growth of dispersoids, growth of constituents, and the resulting change in the solid solution concentration. Alsoft is a physical softening model which combines the effects of recovery and recrystallization.Precipal was originally implemented in Fortran 77, while the softening model, Alsoft, is implemented in Python. It would be beneficial for both the precipitation and softening model to be coupled with each other, as both models provide parameters and state variables that are given as input parameters in the other model (e.g information about the precipitates from Precipal can be used to calculate the Zener-drag, currently given as an external input parameter in Alsoft).In order to facilitate this coupling the precipitation model is reimplemented in Python. This model is then validated against the old implementation, and a parameter sensitivity study is performed to identify the most critical input parameters. The new implementation of the precipitation model is then coupled with the softening model and simulations has been performed and compared with experimental data.Precipal consists of two different precipitation models: a physical model based on physical equations, and one phenomenological model which introduces a number of fitting parameters which are determined experimentally. The physical model was shown to have too fast and abrupt precipitation behavior compared with experimental results. The phenomenological model on the other hand was able to reproduce the experimental precipitation behavior at a given temperature, but failed to successfully predict the effect of different annealing temperatures.The effects on the simulated recrystallization kinetics due to the coupling was found to be minimal, except when the precipitation halted recrystallization completely due to a large Zener-drag. The reason for this lacking effect it believed to be the assumption of site-saturation nucleation in Alsoft, which implies that the Zener-drag effect from concurrent precipitation on recrystallization nucleation is not modeled.
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Sharpe, Jane. "Synthesis and characterisation of Ru2Si3." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/844057/.
Testo completoAbstract (sommario):
Ion Implantation of ruthenium ions into a silicon substrate followed by a high temperature anneal (known as Ion Beam Synthesis) has been used for the first time to fabricate three wafers, under the following conditions. 1. 5.67 X 1016 Ru+ cm-2, beam heated 2. 4.25 X 1016 Ru+ cm-2, heated to ~ 600°C 3. 1.27 X 1017 Ru+ cm-2, heated to ~ 600°C All wafers contained precipitates of the orthorhombic semiconducting silicide of ruthenium, Ru2Si3. No other phase was identified. The samples exhibited a complicated microstructure, with 16 different orientation variants identified, and a high degree of disorder (~ +11% strain). The first optical measurements ever carried out on this material are reported here. Absorption measurements in transmittance yielded a direct band gap, in the region of ~ 0.9eV, 0.87eV, and 0.92eV for wafers 1, 2, and 3 respectively. No discernible variation of band gap magnitude with measurement temperature was found. Upon sequential annealing, the direct band gap magnitude remained constant up to ~ 650°C after which it shifted to above that of silicon, possibly due to a change in microstructural disorder as the precipitates increase in size. This observation was confirmed by several single step anneals at various temperatures above 650°C. No photoluminescence was observed in any of the samples.
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Stålnacke, Emil. "Microstructure-corrosion interrelations in new low-lead and lead-free brass alloys." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217355.
Testo completoAbstract (sommario):
In new low-lead and lead-free brass alloys, it is not understood how the corrosion properties,such as dezincification, are related to material composition as well as annealing temperatureand duration. This study aims to fill this knowledge gap by mapping sixteen annealingconditions and three different brass alloy compositions to their respective microstructure anddezincification performance. It was found that high dezincification depth was a result ofannealing temperatures at 300°C – 400°C, which promoted precipitation of intermetallicAlAs-particles along grain boundaries, twins and lead particles as well as precipitation of β-phase along grain boundaries. Their presence was correlated to high micro additions ofaluminium or iron in the material composition. An additional compositional factorcontributing to precipitation of high amount of β-phase was low copper/zinc-ratio.
20
Salih, Mohammed Zakria [Verfasser]. "The effect of magnetic annealing on crystallographic texture, microstructure and magnetic properties development in Fe-2.6%Si / Mohammed Zakria Salih." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2014. http://d-nb.info/1054128510/34.
Testo completo
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Haase, Christian [Verfasser], Dmitri A. [Akademischer Betreuer] Molodov, and Wolfgang [Akademischer Betreuer] Bleck. "Texture and microstructure evolution during deformation and annealing of high-manganese TWIP steels / Christian Haase ; Dmitri A. Molodov, Wolfgang Bleck." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130590003/34.
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Vazquez, Brian K. "The effects of isothermal deformation and annealing on the microstructure of nickel-aluminum-bronze in relation to the friction stir process." Thesis, Monterey, Calif. : Naval Postgraduate School, 2003. http://edocs.nps.edu/npspubs/scholarly/theses/2003/Dec/03Dec%5FVazquez.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2003.<br>Thesis Advisor(s): McNelley, Terry R. "September 2008." Description based on title screen as viewed on January 21, 2009. Includes bibliographical references (p. 57-59). Also available in print.
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Kisko, A. (Anna). "Microstructure and properties of reversion treated low-Ni high-Mn austenitic stainless steels." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212159.
Testo completoAbstract (sommario):
Abstract In this thesis, the influence of reversion and recrystallization annealing on microstructure and mechanical properties was studied in metastable austenitic low-Ni high-Mn stainless steels, some alloyed with up to 0.45 wt.% Nb. Further, the effect of the various microstructures created by reversion and recrystallization on strain-induced martensite transformation in tensile testing was investigated. The aim was to achieve excellent combinations of strength and ductility in the steels and to improve understanding of the behaviour of ultrafine-grained austenitic stainless steels during deformation. All the steels were cold-rolled up to 60% thickness reduction producing up to 60% strain-induced α’-martensite in the austenitic structure. Annealing was carried out using a Gleeble thermomechanical simulator between 450–1100 °C for durations of 0.1–1000 s. The resultant microstructures were examined using different research equipment and methods. Regardless of the amount of Nb alloying, shear- and diffusion-controlled reversion could be completed by annealing at 700 °C, although at this temperature no recrystallization of the untransformed cold-rolled austenite occurred. At 800 °C, however, the cold-rolled austenite recrystallized, producing a non-uniform grain structure comprising ultrafine-grained areas formed via reversion and coarser ones formed by recrystallization of the retained austenite. At 900 °C, a uniform fine austenite grain size of about 2 μm was obtained. At higher annealing temperatures of 1000–1100 °C, normal grain growth of fine grains took place during prolonged annealing in steel with no Nb. However, grain growth was effectively retarded by alloying with 0.28 wt.% Nb. The non-uniform structures consisting of reverted and retained austenite exhibited excellent combinations of yield strength and uniform elongation. The results also showed that tensile strain-induced martensite nucleation sites and α’-martensite formation vary in a complex way depending on grain size<br>Tiivistelmä Väitöstyössä tutkittiin reversiohehkutuksen vaikutusta metastabiilin 1% nikkeliä ja 9% mangaania sisältävien austeniittisten ruostumattomien terästen mikrorakenteeseen ja mekaanisiin ominaisuuksiin sekä austeniitin raekoon ja mikrorakenteen vaikutusta muokkausmartensiitin syntyyn vetokokeessa. Koeteräksistä osa oli lisäksi niobiseostettuja. Tavoitteena oli nostaa teräksien lujuutta ja ymmärtää ultrahienorakeisen austeniittisten ruostumattomien terästen käyttäytymistä muokkauksessa. Teräkset kylmämuokattiin 60% valssausreduktiolla, jolloin austeniittiseen rakenteeseen muodostui muokkausmartensiittia enimmillään 60%. Reversiohehkutukset tehtiin Gleeble termomekaanisella simulaattorilla lämpötiloissa 450–1100 °C ja 0.1–1000 s pitoajoilla. Saatuja mikrorakenteita tutkittiin eri tutkimuslaitteistoilla ja -menetelmillä. 700 °C hehkutuksessa leikkautumalla ja diffuusion välityksellä tapahtuva reversio oli nopea myös niobi-seostetuilla teräksillä, mutta rekristallisaatiota ei tapahtunut. 800 °C hehkutuksessa muokkauksessa teräksiin jäänyt austeniitti rekristallisoitui, mutta raerakenne muodostui epätasaiseksi koostuen reversion tuottamasta ultrahienoista rakeista ja jäännösausteniitin rekristallisaation tuottamista karkeammista rakeista. Sitä vastoin hehkutus 900 °C:ssa tuotti tasainen 2 μm austeniitin raekoon. Pitkissä hehkutuksissa korkeammissa lämpötiloissa 1000–1100 °C niobi-seostamattomissa teräksissä tapahtui hienojen rakeiden normaalia rakeenkasvua. Kuitenkin 0.28p-% niobi-seostuksen havaittiin oleva riittävä estämään rakeenkasvu. Reversion ja osittaisen rekristallisaation tuottamilla raerakenteilla saatiin erinomaiset myötölujuus-tasavenymäyhdistelmät. Vetokokeissa martensiitin ydintymispaikat ja -nopeus vaihtelivat monimutkaisella tavalla raekoosta riippuen
24
Dixon, Richard John. "Ion scattering studies of the surface and near surface region of metals and semiconductors." Thesis, University of Warwick, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343788.
Testo completo
25
Lienshöft, Laura, Paul Chekhonin, Dana Zöllner, et al. "Static recrystallization and grain growth of accumulative roll bonded aluminum laminates." Cambridge University Press, 2017. https://tud.qucosa.de/id/qucosa%3A70745.
Testo completoAbstract (sommario):
Aluminum laminates of high and technical purity layers were produced by accumulative roll bonding (ARB) at room temperature. To study the thermal stability, the laminates after 2 to 9 ARB cycles were annealed between 100 and 400 °C for one hour. Changes of the microstructure were analyzed by electron backscatter diffraction. For low ARB cycle numbers (4 or below) and 300 °C annealing temperature, the deformed technical pure layers start to recrystallize while the high-purity coarse recrystallized layers experience intralayer grain growth. For higher ARB cycle numbers (6 and 8) and an annealing temperature of 300 °C or above, the ultra-fine grained layers of technical purity are consumed by the layer overlapping growth of high-purity grains producing a banded grain structure. For 9 ARB cycles and at an annealing temperature of 400 °C, a globular grain structure develops with grain sizes larger than twice the layer thickness. The effect of impurities on recrystallization and grain growth of ARB laminates is discussed with regard to tailoring its microstructure by heat treatment. For further analyses, the results are compared with Potts model simulations finding a rather good qualitative agreement with the experimental data albeit some simplified model assumptions.
26
Almeida, Harrizon Lima de. "Estudo microestrutural em mineralização aurífera do tipo-veio hospedada em zona de cisalhamento : caso do depósito Sertãozinho, província Borborema, NE do Brasil /." Rio Claro : [s.n.], 2003. http://hdl.handle.net/11449/103019.
Testo completoAbstract (sommario):
Orientador: Peter Christian Hackspacher<br>Banca: Luiz Sergio Amarante Simões<br>Banca: Nelson Angeli<br>Banca: Carlos José Archanjo<br>Banca: Marcos Egydio da Silva<br>Resumo: A zona de cisalhamento Itapetim (ZCI) desenvolveu foliação e lineação nos diferentes tipos de rochas, milonitos a ultramilonitos. Muitos dos tipos de microestruturas observadas na ZCI preservam evidências de condições metamórficas de alto grau e baixo grau de temperatura. O padrão das orientações preferenciais dos eixos [c] de quartzo, obtida a partir de agregados policristalinos deformados, mostra dois diferentes tipos de simetrias, guirlandas do tipo I e simples. A análise da textura sugere partição da deformação com cisalhamento coaxial e não coaxial na ZCI. Um veio de quartzo mineralizado em ouro encaixado em rocha ultramilonítica, constitui a zona de precipitação hidrotermal. O veio é bandado por segmentos de turmalina, o qual inclui agregados de grãos de quartzo maciço entre as bandas. Os grãos de quartzo mostram contatos poligonais e restritos limites intumescentes. O último sugere recristalização dinâmica por migração de limite de grão e os grãos poligonais (microestrutra em espuma) são melhor explicados por annealing. Os padrões de eixos [c] de quartzo obtido no veio aurífero é idêntico ao observado nos ultramilonitos da ZCI. Este padrão é interpretado como uma textura preservada formada durante o cisalhamento não coaxial. A estrutura bandada é interpretada como o resultado de variações da pressão de fluidos e a formação microfraturas, associadas a eventos de crack-seal. Mecanismos de crack-seal foram ativos antes ou durante a deformação da ZCI. As feições microestruturais suportam evidências para a última possibilidade.<br>Abstract: The Itapetim shear zone(ISZ) developed both foliation and lineation in the different rock types, from mylonites to ultramylonites. Most of the microstructure types observed in the ISZ preserve evidence of high temperature metamorphic conditions. The quartz [c]-axis, of deformed polycrystalline aggregates, show two distinct symmetries, type I crossed girdles and single girdles. The geometrical analysis of texture, suggest non-coaxial shear for deformation in ISZ. A gold mineralized quartz vein hosted in ultramylonitic rocks, constitutes the hydrothermal precipitation zone. The vein is banded by tourmiline segments, which include massive quartz grains aggregates between the bands. The quartz grains show polygonal contacts and minor intumescent limits. These latter suggest grain boundary migration recrystallization and the polygonal grains seem to be best explained by the annealing after stopping the shear deformation. The quartz [c]-axis obtained in the auriferous vein shows the same single girdle pattern observed in the ultramylonites of the ISZ. This pattern is interpreted as a preserved texture formed during the shear deformation. The banded structure is interpreted as the result of variations of the fluid pressure and the formation of microfractures, associated the crack-seal events. Crack-seal mechanisms can have been active previous or during the deformation of the IZS. The microstructurals features supports evidences for the last possibility.<br>Doutor
27
AKANI, MOHAMED. "Elaboration du silicium polycristallin par projection plasma : microstructure et proprietes electriques." Paris 6, 1986. http://www.theses.fr/1986PA066613.
Testo completoAbstract (sommario):
Obtention de rubans autosupportes ou supportes par differents substrats par projection plasma a partir de poudre de silicium. Optimisation du procede. Mesure des caracteristiques des rubans obtenus (porosite, densite, resistivite, mobilite de hall) avant et apres recuit, et apres recristallisation par bombardement electronique. Evolution des caracteristiques electriques avec le dopage. Mesure des proprietes photoelectroniques
28
Gasmi, Assia. "Effet de la nanostructuration sur le comportement thermomécanique du Nitinol." Electronic Thesis or Diss., Université de Montpellier (2022-....), 2024. http://www.theses.fr/2024UMONS018.
Testo completoAbstract (sommario):
La présente thèse s’intéresse à l'alliage à mémoire de forme NiTi, en se concentrant sur l'influence du procédé de nanostructuration superficielle SMAT sur son comportement thermomécanique. À travers quatre chapitres distincts, elle rappelle les principales caractéristiques des alliages à mémoire de forme (AMF), mettant en avant les propriétés exceptionnelles de l'alliage NiTi, et explorant le traitement de nanocristallisation superficielle (SMAT). La caractérisation microstructurale est ensuite approfondie, notamment en étudiant les effets du traitement thermique de recuit et du SMAT sur la transition de phase. Le troisième chapitre se concentre sur les méthodes d'analyse thermomécanique adaptées au NiTi, en examinant les essais de traction et de nanoindentation. Enfin, le quatrième chapitre analyse la caractérisation thermomécanique de l'alliage avant et après le traitement SMAT, mettant en évidence les implications de ces transformations sur son comportement global.La thèse contribue à la compréhension des effets du procédé SMAT sur l'alliage NiTi, révélant des liens entre la microstructure, les phases présentes et les propriétés mécaniques. Les résultats ouvrent des perspectives prometteuses pour la meilleure maîtrise des propriétés de l'alliage NiTi.Les résultats obtenus pour différents traitements SMAT montrent que ce procédé modifie la réponse mécanique du matériau. Elle a aussi une influence sur son état initial, comme l’illustrent les différences dans les courbes de DSC. Les mesures cinématiques (champs de vitesses de déformation) et calorimétriques (champ de source de chaleur) indiquent aussi l’apparition de différences notables dans les réponses en fonction des paramètres de traitement SMAT. L'exploration du comportement lors de cycles de charge/décharge montre une réponse qui se stabiliser après quelques cycles. Les effets de couplage semblent être prépondérants par rapport aux effets dissipatifs. Ces observations devraient être étendues à des chargements en fatigue afin de mieux mettre en évidence les éventuels effets dissipatifs. De même, l’utilisation de modèles d’interprétation plus élaborés permettrait de mieux tenir compte des effets de structure et d’enrichir la compréhension de la relation entre le procédé et les évolutions des propriétés<br>This thesis focuses on the shape memory alloy NiTi, with a specific emphasis on the influence of the surface nanostructuring process SMAT on its thermomechanical behavior. Through four distinct chapters, it revisits the main characteristics of shape memory alloys (SMAs), highlighting the exceptional properties of the NiTi alloy and exploring the surface nanocrystallization treatment (SMAT). Microstructural characterization is then deeply investigated, particularly by studying the effects of annealing heat treatment and SMAT on phase transition. The third chapter focuses on thermomechanical analysis methods suitable for NiTi, examining tensile tests and nanoindentation. Finally, the fourth chapter analyzes the thermomechanical characterization of the alloy before and after SMAT treatment, highlighting the implications of these transformations on its overall behavior.This thesis contributes to understanding the effects of the SMAT process on the NiTi alloy, revealing links between microstructure, present phases, and mechanical properties. The results offer promising perspectives for better control of the properties of the NiTi alloy.The results obtained for different SMAT treatments show that this process modifies the mechanical response of the material. It also has an influence on its initial state, as illustrated by differences in DSC curves. Kinematic (strain rate fields) and calorimetric (heat source field) measurements also indicate notable differences in responses depending on SMAT processing parameters. Exploration of behavior during load/unload cycles shows a response that stabilizes after a few cycles. Coupling effects seem to be predominant compared to dissipative effects. These observations should be extended to fatigue loading to better highlight any dissipative effects. Similarly, the use of more elaborate interpretation models would allow better consideration of structural effects and enrich the understanding of the relationship between the process and property evolutions
29
Kench, P. J. "Microstructures of group III-nitrides after implantation with gallium." Thesis, University of Surrey, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343459.
Testo completo
30
Couchet, Clélia. "New insights in understanding the interaction between recrystallization and phase transformation during intercritical annealing in DP steels." Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0019.
Testo completoAbstract (sommario):
La formation des microstructures est cruciale pour la sidérurgie. Pour les aciers Dual Phase (DP), utilisés dans l'automobile, celle-ci a lieu lors du recuit intercritique après le laminage à froid. Après la chauffe, la microstructure est composée de ferrite et d'austénite recristallisées. Lors du refroidissement, l'austénite se transforme partiellement en ferrite puis en martensite pour atteindre la microstructure ferrite/martensite finale. L'austénitisation est cruciale pour contrôler les fractions et tailles de phase finales et donc leurs propriétés mécaniques. De nombreuses études montrent que la vitesse de chauffe contrôle la cinétique de transformation et la morphologie de l'austénite ("collier" ou "bande"). Ces effets sont souvent attribués au chevauchement entre la recristallisation de la ferrite et la formation de l'austénite, mais les mécanismes sous-jacents restent controversés. En utilisant les progrès récents dans les expériences in situ sur les lignes de faisceaux synchrotron, ce travail de doctorat vise à proposer une nouvelle compréhension des interactions entre la recristallisation de la ferrite et la formation de l'austénite et à développer un modèle prédictif pour la cinétique de formation de l'austénite. Le développement expérimental principal de cette thèse est une nouvelle technique d'analyse basée sur la diffraction des rayons X de haute énergie pour suivre in situ la recristallisation et les transformations de phase pendant la phase de recuit, y compris à des vitesses de chauffe élevées. Notre nouvelle méthode, appelée Isolated Diffraction Spot Tracking (IDST), est d'abord validée pour étudier la recristallisation sur des aciers ferritiques modèles. Ces mesures in situ sont complétées par des observations des microstructures après traitements interrompus en microscopie (optique, microscopie électronique à balayage et à transmission), et par des mesures de chimie locale (spectroscopie de rayons X à dispersion d'énergie et de dispersion en longueur d'onde). Nous reproduisons d'abord des expériences pour étudier l'influence de la vitesse de chauffe sur l'acier étudié pendant le recuit intercritique. Dans celles-ci, le chevauchement entre la recristallisation de la ferrite et la formation de l'austénite est régi par la vitesse de chauffe. Ensuite, nous avons conçu des expériences pour décorréler l'effet de la vitesse de chauffe et ce chevauchement. La vitesse de chauffe est fixée pour maintenir les mêmes conditions pour les mécanismes thermo-activés, mais le micro-alliage au niobium et le taux de laminage à froid plus faible retardent la recristallisation de la ferrite. Ces expériences montrent que la cinétique de transformation de l'austénite n'est pas contrôlée par la recristallisation, mais par la seule condition thermodynamique de l'interface de transformation et peut-être par la distance de diffusion dans les microstructures. Enfin, une analyse thermocinétique détaillée des mécanismes de formation de l'austénite au cours du recuit intercritique est proposée sur la base de simulations DICTRA/Thermo-Calc et de notre travail expérimental. L'effet des éléments d'alliage mineurs sur la cinétique de croissance de l'austénite est étudié et un modèle prédictif pour la formation de l'austénite pendant le recuit intercritique est développé. Finalement, ce travail montre l'absence d'effet significatif de la concomitance des mécanismes étudiés sur la cinétique de formation de l'austénite au cours de la chauffe. Nous montrons que la cinétique de formation de l'austénite est contrôlée par la diffusion. La différence de cinétique de formation de l'austénite au cours de la phase de maintien est expliquée par des considérations microstructurales, affectant les distances de diffusion<br>The formation of microstructures is a crucial step for steelmakers. In the case of DP steels, used for automotive construction, this formation takes place during intercritical annealing after cold-rolling. During this thermal treatment, after the heating step, the microstructure is made of recrystallized ferrite and austenite. During cooling, the austenite partially transforms into ferrite and then into martensite to reach the expected final ferrite/martensite microstructure. The austenitization step is therefore crucial for the manufacturers of these steels, to control the final phase fractions and sizes and, consequently, their mechanical properties. Numerous studies show that the heating rate controls the transformation kinetics and the morphology of the austenite ("necklace" or "banded"), but the underlying mechanisms remains a bone of contention. The overlap between ferrite recrystallization and austenite formation is often made responsible for these effects, through different mechanisms. Using recent advances in in situ experiments on synchrotron beamlines, this PhD proposes a new insight in the understanding of the interactions between ferrite recrystallization and austenite formation and develops a predictive model for the austenite formation kinetics. The main experimental development of this thesis is a new coupled time-resolved analysis technique, based on in situ High-Energy X-Ray Diffraction to track recrystallization and phase transformations during the annealing phase, including at high heating speeds. Our new method, called Isolated Diffraction Spot Tracking (IDST), is first validated to study recrystallization on model ferritic steels. These in situ measurements are supplemented by observations of microstructures after interrupted treatments in microscopy (optical, Scanning Electron Microscopy and Transmission Electron Microscopy), and from local chemistry measurements (Energy-Dispersive X-ray Spectroscopy and Wavelength Dispersion Spectroscopy)We first reproduce experiments to study the influence of the heating rate on the studied steel during the intercritical annealing. In such experiments, the overlap between ferrite recrystallization and austenite formation is governed by the heating rate. To go further, we designed experiments to decorrelate the effect of the heating rate and this overlap. During these, the heating rate is fixed to maintain the same conditions for thermo-activated mechanisms, but the niobium micro-alloying and lower cold-rolling ratio are used to delay ferrite recrystallization. These experiments show unambiguously that austenite transformation kinetics is not controlled by the recrystallization, but by the sole thermodynamic condition of interfaces and maybe by the diffusion distance in the microstructures. Finally, we propose a detailed thermo-kinetics analysis of the mechanisms of austenite formation during the intercritical annealing based on DICTRA/Thermo-Calc simulations and on our experimental work. The effect of minor alloying elements on the austenite growth kinetics is investigated. This work finally proposes new predictive models for austenite formation during the intercritical annealing. This PhD work finally shows no significant effect of the concomitance of the two studied mechanisms on the austenite formation kinetics along the heating stage. We demonstrate that the austenite formation kinetics is diffusion-controlled. The difference in austenite formation kinetics along the holding stage is explained by microstructural considerations, affecting the diffusion distances
31
Sakael, Clément. "Modélisation de la microstructure des alliages de Zirconium irradiés : application à un transitoire Accident de Perte de Réfrigérant Primaire et à la restauration en aval du cycle." Electronic Thesis or Diss., Centrale Lille Institut, 2023. http://www.theses.fr/2023CLIL0010.
Testo completoAbstract (sommario):
Le sujet de cette thèse concerne les alliages de zirconium qui sont utilisés pour fabriquer la gaine du crayon combustible et les assemblages combustibles des réacteurs nucléaires à eau pressurisée. Ce type d'alliage est choisi dans le domaine du nucléaire pour sa faible section efficace de capture des neutrons thermiques. Cependant sous irradiation aux neutrons, il est observé des changements de forme et de volume, une augmentation de la dureté et une réduction importante de la ductilité du matériau, ce qui signifie une augmentation de sa fragilisation. Ce travail s’intéresse plus particulièrement à la croissance induite sous irradiation de la gaine qui résulte d’un allongement dans le plan basal et une contraction le long de l’axe c ⃗ de la maille hexagonale de la phase alpha du zirconium. Afin de mieux comprendre ces phénomènes, une approche multi-échelle a été utilisée pour modéliser l’évolution de la microstructure des alliages de zirconium (i) au cours de l’irradiation, (ii) pendant la phase transitoire d’un accident de perte de réfrigérant primaire (APRP) et (iii) au cours de la restauration en aval du cycle. Dans un premier temps, des calculs à l’échelle atomique basés sur la théorie de la fonctionnelle de la densité (DFT) et sur des potentiels empiriques sont réalisés pour déterminer les propriétés et les caractéristiques des amas de défauts ponctuels (amas d’auto-interstitiels, amas de lacunes et boucles de dislocation).Afin de mieux caractériser au mieux les amas d’auto-interstitiels de petitetaille, les énergies de migration et les coefficients de diffusion du di et du tri-auto-interstitiels sontcalculés en dynamique moléculaire en utilisant la DFT. Une partie des résultats obtenus par lescalculs atomiques sont utilisés comme données d’entrée dans un code de type Monte Carlocinétique d’objet (OKMC) qui permet la simulation de l’évolution de la microstructure duzirconium en conditions (i) à (iii)<br>The subject of this thesis concerns zirconium alloys which are used to manufacture the fuel rod cladding and fuel assemblies of pressurized water nuclear reactors. This type of alloy is chosen in the nuclear field for its low thermal neutron capture cross section. However, under neutron irradiation, changes in shape and volume, an increase in hardness and a significant reduction in the ductility of the material are observed, which means an increase in its embrittlement. This work focuses on the irradiation-induced growth of the cladding that results from an elongation in the basal plane and a contraction along the c ⃗ axis of the hexagonal lattice of the alpha phase of zirconium. This phenomenon amplifies beyond a threshold dose that coincides with the nucleation of dislocation loops and the formation of loop alignments as layers parallel to the basal plane. Nevertheless, the mechanisms of nucleation of defect clusters such as dislocation loops are still to be clarified. In order to have a better understanding of these phenomena, a multi-scale approach was used to model the evolution of the microstructure of zirconium alloys (i) during irradiation, (ii) during the transient phase of a loss-of-coolant accident (LOCA) and (iii) during the downstream restoration of the cycle. First, atomic scale calculations based on density functional theory (DFT) and empirical potentials are performed to determine the properties and characteristics of point defect clusters (self-interstitial clusters, vacancy clusters and dislocation loops).In order to have a better characterization of self-interstitial, the migrationenergies and diffusion coefficients of di- and tri-self-interstitials are calculated in moleculardynamics using DFT. Some of the results obtained by atomistic calculations are used as inputdata for an object kinetic Monte Carlo (OKMC) code, which simulates the evolution of themicrostructure of zirconium under conditions (i) to (iii)
32
Ramdani, Hamdane. "Contribution à l'étude d'aimants samarium-cobalt : relation entre les propriétés magnétiques et la microstructure." Rouen, 1987. http://www.theses.fr/1987ROUES034.
Testo completoAbstract (sommario):
Etude d'aimants frittés Sm (Co, Fe, Cu, Zr)(7,29) ayant subi des traitements thermiques différents. Mesure de la coercivité et observation de la microstructure par microscopie électronique en transmission. Corrélation entre les microstructures avant et après recuit a 830°C et les propriétés magnétiques, à partir d'un modèle basé sur la répartition des éléments d'addition
33
Almeida, Harrizon Lima de [UNESP]. "Estudo microestrutural em mineralização aurífera do tipo-veio hospedada em zona de cisalhamento: caso do depósito Sertãozinho, província Borborema, NE do Brasil." Universidade Estadual Paulista (UNESP), 2003. http://hdl.handle.net/11449/103019.
Testo completoAbstract (sommario):
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almeida_hl_dr_rcla.pdf: 806140 bytes, checksum: 7940276ecd62a931d89c15464ccc97db (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>A zona de cisalhamento Itapetim (ZCI) desenvolveu foliação e lineação nos diferentes tipos de rochas, milonitos a ultramilonitos. Muitos dos tipos de microestruturas observadas na ZCI preservam evidências de condições metamórficas de alto grau e baixo grau de temperatura. O padrão das orientações preferenciais dos eixos [c] de quartzo, obtida a partir de agregados policristalinos deformados, mostra dois diferentes tipos de simetrias, guirlandas do tipo I e simples. A análise da textura sugere partição da deformação com cisalhamento coaxial e não coaxial na ZCI. Um veio de quartzo mineralizado em ouro encaixado em rocha ultramilonítica, constitui a zona de precipitação hidrotermal. O veio é bandado por segmentos de turmalina, o qual inclui agregados de grãos de quartzo maciço entre as bandas. Os grãos de quartzo mostram contatos poligonais e restritos limites intumescentes. O último sugere recristalização dinâmica por migração de limite de grão e os grãos poligonais (microestrutra em espuma) são melhor explicados por annealing. Os padrões de eixos [c] de quartzo obtido no veio aurífero é idêntico ao observado nos ultramilonitos da ZCI. Este padrão é interpretado como uma textura preservada formada durante o cisalhamento não coaxial. A estrutura bandada é interpretada como o resultado de variações da pressão de fluidos e a formação microfraturas, associadas a eventos de crack-seal. Mecanismos de crack-seal foram ativos antes ou durante a deformação da ZCI. As feições microestruturais suportam evidências para a última possibilidade.<br>The Itapetim shear zone(ISZ) developed both foliation and lineation in the different rock types, from mylonites to ultramylonites. Most of the microstructure types observed in the ISZ preserve evidence of high temperature metamorphic conditions. The quartz [c]-axis, of deformed polycrystalline aggregates, show two distinct symmetries, type I crossed girdles and single girdles. The geometrical analysis of texture, suggest non-coaxial shear for deformation in ISZ. A gold mineralized quartz vein hosted in ultramylonitic rocks, constitutes the hydrothermal precipitation zone. The vein is banded by tourmiline segments, which include massive quartz grains aggregates between the bands. The quartz grains show polygonal contacts and minor intumescent limits. These latter suggest grain boundary migration recrystallization and the polygonal grains seem to be best explained by the annealing after stopping the shear deformation. The quartz [c]-axis obtained in the auriferous vein shows the same single girdle pattern observed in the ultramylonites of the ISZ. This pattern is interpreted as a preserved texture formed during the shear deformation. The banded structure is interpreted as the result of variations of the fluid pressure and the formation of microfractures, associated the crack-seal events. Crack-seal mechanisms can have been active previous or during the deformation of the IZS. The microstructurals features supports evidences for the last possibility.
34
Granbom, Ylva. "Structure and mechanical properties of dual phase steels : An experimental and theoretical analysis." Doctoral thesis, KTH, Mekanisk metallografi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24869.
Testo completoAbstract (sommario):
The key to the understanding of the mechanical behavior of dual phase (DP) steels is to a large extent to be found in the microstructure. The microstructure is in its turn a result of the chemical composition and the process parameters during its production. In this thesis the connection between microstructure and mechanical properties is studied, with focus on the microstructure development during annealing in a continuous annealing line. In-line trials as well as the lab simulations have been carried out in order to investigate the impact of alloying elements and process parameters on the microstructure. Further, a dislocation model has been developed in order to analyze the work hardening behavior of DP steels during plastic deformation. From the in-line trials it was concluded that there is an inheritance from the hot rolling process both on the microstructure and properties of the cold rolled and annealed product. Despite large cold rolling reductions, recrystallization and phase transformations, the final dual phase steel is still effected by process parameters far back in the production chain, such as the coiling temperature following the hot rolling. Lab simulations showed that the microstructure and consequently the mechanical properties are impacted not only by the chemical composition of the steel but also by a large number of process parameters such as soaking temperature, cooling rate prior to quenching, quench and temper annealing temperature.<br>QC 20101004
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Lectard, Eric. "Structures, microstructures et coercitivité des alliages Sm(Co,Cu)5." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0139.
Testo completoAbstract (sommario):
L'objectif de ce travail est d'etudier les liens entre composition chimique, microstructure et coercitivite des phases magnetiques de type sm(co,cu)5. L'etude est realisee sur des alliages de microstructures typiques (alliages solidifies, homogeneises frittes ou isotropes, monocristaux) et de composition variees, elabores et caracterises a differentes echelles. Les microstructures multiphasees obtenues par solidification sont de type dendritique : la phase de cristallisation primaire, d'apparence biphasee, est une phase sm(co,cu)#5 dont les segregations de solidification simulent une demixtion. La phase interdentrique est une phase riche en sm et cu de type 5:19. Les cycles d'hysteresis de ces aimants sont interpretes en terme de sommation des contributions des 3 phases considerees comme magnetiquement independantes. Les alliages homogeneises-trempes, pratiquement monophases, presentent une coercitivite de type ancrage, qui augmente fortement avec le taux de substitution co/cu. Quelle que soit la composition, le champ coercitif s'eleve apres un recuit de quelques heures a basse temperature ou un refroidissement lent depuis 1100c. Les etudes microstructurales d'une part, qui ne permettent pas la detection de defauts susceptibles d'ancrer les parois de bloch, et l'etude magnetique sur monocristaux d'autre part, conduisent a proposer un mode de coercitivite non classique, de type intrinseque. Le renforcement du champ coercitif apres traitement thermique est interprete suivant le meme modele. Des etudes thermiques et cristallographiques couplees, menees sur une composition d'alliage fixee, revelent la presence d'une transformation structurale en dessous de 930c.
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Royer, Agnès. "Evolutions thermique et mécanique de la microstructure de superalliages monocristallins étudiées par diffusion centrale et diffraction (neutrons, rayons [gamma])." Grenoble 1, 1993. http://www.theses.fr/1993GRE10097.
Testo completoAbstract (sommario):
Les experiences de diffraction et de diffusion des rayonnements gamma et neutron nous ont permis d'etudier la microstructure du superalliage monocristallin am1 ainsi que son evolution en fonction de la temperature. Ces experiences ont pour la plupart ete realisees in situ en temperature et nos resultats qui sont relatifs a un grand nombre de precipites, ne sont pas sensibles aux heterogeneites locales de composition chimique. Nous avons analyse la morphologie des precipites gamma prime a l'aide d'experiences de diffusion aux petits angles des neutrons, au cours des phenomenes de precipitation et de coalescence des precipites gamma prime. La remise en solution de ces precipites a ete etudiee par diffraction neutron jusqu'a complete dissolution. Afin de mieux comprendre les mecanismes qui regissent l'evolution de la morphologie des precipites, nous avons etudie en temperature differents parametres microstructuraux. Par diffraction gamma, nous avons mis en evidence une distorsion tetragonale au sein du materiau et le desaccord parametrique entre les deux phases a pu etre mesure par diffraction neutrons a grands angles de bragg. La synthese des resultats obtenus au cours de ces differentes experiences, nous a permis d'etablir un modele qui prevoit l'evolution des parametres de maille des phases gamma et gamma prime en fonction de la temperature lors de recuits thermiques et sous contrainte
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Pierce, Frank Allen. "The isothermal deformation of nickel aluminum bronze in relation to friction stir processing." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://handle.dtic.mil/100.2/ADA430658.
Testo completoAbstract (sommario):
Thesis (M.S. in Mechanical Engineering) Naval Postgreaduate School, June 2004.<br>Thesis Advisor (s): Terry R. McNelley. "June 2004." Includes bibliographic references (p. 53-54). Also available in print.
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Trombley, Melissa L. "Localized annealing of polysilicon microstructures by inductively heated ferromagnetic films /." Available online. Click here, 2007. http://sunshine.lib.mtu.edu/ETD/DISS/2007/Electrical&ComputerEng/trombleym/diss.pdf.
Testo completo
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Narayanan, Rajmohan. "Computer simulation of textural and microstructural changes during annealing processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq64629.pdf.
Testo completo
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Cushway, Clayton Andrew. "The Microstructural Annealing Response of Cold Gas Dynamically Sprayed Al 6061." UNF Digital Commons, 2018. https://digitalcommons.unf.edu/etd/846.
Testo completoAbstract (sommario):
The Cold-Gas Dynamic-Spray process also known as Cold Spray (CS) has been researched for three decades. The CS process is a solid-state deposition technique via supersonic velocity of powder particles at a temperature significantly below the melting point of the spray material. This thesis presents background on the overall CS process parameters, and additional information on the microstructural and mechanical properties of typical Cold Sprayed materials.This Thesis primarily presents a study on the microstructural annealing response of CS Al 6061. It should be noted that for this study, the term “annealing” is used in the sense of the classical metallurgical definition of annealing, and not a specific temper designation for the 6061 alloy. Cross sections of CS Al 6061 were imaged with a scanning electron microscope (SEM) in secondary electron (SE), backscatter electron (BSE), and electron backscatter diffraction (EBSD) imaging mode for quantitative and qualitative information on the grain size and orientation of the CS microstructure. The detailed SE, BSE and EBSD mode images present the grain size and grain orientation of the original powder, as received (AR) state and after heat treating at 200°C for 1 hour, 10 hours, and 100 hours. Three different regions, characterized with distinctly differing microstructures, are labeled as low, medium, and high deformation regions, and their microstructures, and evolving features are discussed. Vickers microhardness testing are performed to examine the differences in hardness values between different heat treatments, and for correlation with the level of deformation and grain refinement in the microstructure. SEM imaging was used in BSE mode to correlate microhardness variation to the different regions within the CS microstructure.
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Huang, Yi-Hsuan, and 黃怡萱. "Effect of annealing on the microstructure of MnBi alloy thin films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7twu24.
Testo completoAbstract (sommario):
碩士<br>國立中興大學<br>材料科學與工程學系所<br>106<br>The composite films of Ag/MnBi on Si substrate was prepared by dual ion-beam deposition technique. The structural and magnetic properties of the composite films were studied by X-ray diffraction (XRD) , transmission electron microsopy (TEM) , Vibrating sample magnetometer (VSM) ,respectively .
XRD results have shown that MnBi layer of H.C.P with a＝4.27 Å、c＝6.12 Å, Ag layer consisted of F.C.C with a=4.05Å . TEM results have shown that the grain size of polycrystalline composite film range from 3~14 nm.
After annealing , we can find from TEM results that Ag layer and MnBi layer interface is not smooth and suspected diffusion. This phenomenon maybe overlay Ag has a high diffusivity or Ag is a poor barrier. Magnetic properties at room temperature (T= 298K) and magnetic field along the parallel and perpendicular to the film surface heve been measured ,we found that the Ag / MnBi alloy film without ferromagnetism before and after annealing.
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Lindell, David. "Process-microstructure-corrosion interrelations for stainless steel." Doctoral thesis, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159072.
Testo completoAbstract (sommario):
Stainless steels were first developed in the early 20th century and have since then emerged as a very diverse class of engineering materials. Along with steels having new combinations of properties, there is a continuous development of new technologies allowing the material to be produced in a faster and more energy effcient manner. A prerequisite for new technologies to be adapted quicklyis a fundamental understanding of the microstructure evolution throughout theprocess chain. The first part of this thesis has been dedicated to the annealing and pickling processes from a process-microstructure perspective. In the second part the concept of utilising crystallographic texture as a way to attain microstructures with new combinations of properties has been evaluated. In the first part, annealing can be regarded as a high temperature oxidation process, resulting in chromium depletion that necessitate subsequent chemical pickling. Chemical pickling, on the other hand, is basically a wet-corrosion process and hence more difficult for highly corrosion-resistant grades. The chromium depleted layer was found to be enriched in austenite in case of duplex stainless steel UNS S32205 (Paper I) and this may inuence the pickling process. Proper pretreatment like shot-blasting dramatically increases the pickling rate because it provides the pickling acid with access to the chromium depleted layer (Paper II). Oxidation kinetics for S30400 in conditions relevant to strip annealing do not seem to be affected by the choice of air/oxygen as oxidiser even though the latter results in substantially higher water content (Paper III). This gives new possibilities regarding both cost savings and increased throughput. In the second part, the effect of crystallographic texture on resistance towards corrosion of S31603 in a solution of FeCl3 and AlCl3 in ethanol/glycerol and in 30 vol% H2SO4 is investigated. In the former, high density surfaces {1111} and {100} are less prone for pit nucleation, however the effect is relativelysmall. In H2SO4 pronounced crystallographic anisotropy is observed inwhich the corrosion rate increase in the order {111} < {110} ≤ {100} (Paper IV).For corrosion at high temperatures, chromium diffusion is governed by randomhigh angle boundaries with ~20—55° misorientation. The possibilities to alter the texture in austenitic stainless steels by means of warm-rolling and annealing has been evaluated for S30403 and S31603. During warm-rolling, both steels develop the copper-type texture in contrast to the brass-type texture observedat room temperature. However only S30403 is prone to recrytallise cube texture during subsequent annealing (Paper V).<br><p>QC 20150121</p>
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Bacaltchuk, Cristiane Maria Basto Garmestani H. "Effect of magnetic annealing on texture and microstructure development in silicon steel." Diss., 2005. http://etd.lib.fsu.edu/theses/available/etd-01042005-150011/.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Florida State University, 2005.<br>Advisor: Dr. Hamid Garmestani, Florida State University, College of Engineering, Department of Mechanical Engineering Title and description from dissertation home page (viewed June 14, 2005). Document formatted into pages; contains xv, 115 pages. Includes bibliographical references.
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Li, Zong Shu. "Microstructure Evolution and Mechanical Properties of Electroformed Nano-grained Nickel upon Annealing." Thesis, 2010. http://hdl.handle.net/1807/25763.
Testo completoAbstract (sommario):
Nano-grained nickel produced by electroforming technique was investigated for its microstructure evolution and mechanical properties upon annealing. It was found that during low temperature annealing (T<250 oC), electroformed nano-grained nickel showed scattered and isolated abnormal grain growth, followed by a major abnormal grain growth at 320 oC. A secondary abnormal grain growth, featuring faceted grain boundaries, was observed at a higher annealing temperature (T=528 oC). A semi-in-situ observation using optical microscopy was conducted to track the movement of the faceted grain boundaries, and it was found that these boundaries were mostly immobile. The mechanical properties under various annealing conditions were studies using hardness and tensile testing. The hardness was observed to decrease with increasing annealing temperature. The material became very brittle after annealing at 320 oC or higher temperatures. Fractography investigation showed that the brittleness is caused by intergranular fracture.
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Huang, Shang-Feng, and 黃尚峰. "Effect of Different Annealing Processes on Microstructure of Fe Implanted Silicon Substrate." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/30514540774266800120.
Testo completoAbstract (sommario):
碩士<br>國立清華大學<br>材料科學工程學系<br>92<br>Semiconducting β-FeSi2 have attracted great attention in the recent decade. Because it has a direct band-gap of about 0.8eV, and it can emit a light of 1.55μm. With this property, silicon based IR-LED(Light emitting device) and IR-Sensor can be synthesized. But its optical property is still controversial, M. G. Grimaldi et al. suggested that the luminescence of β-FeSi2 precipitates is related to its location. So that our study is using a variety of annealing process to see if we can control the location of β-FeSi2 precipitates.
The general method of ion beam synthesized(IBS) β-FeSi2 precipitates is to heat target during ion implantation. After annealing at 830oC for 18 hours, β-FeSi2 will precipitate inside specimen. In our experiment, ion implantation will be carried out under room temperature. After annealing at 830oC for 18 hours, we can observe β-FeSi2 precipitates close to surface by TEM images. Because heating of target can avoid the amorphization of silicon substrate, and the diffusivity of Fe atom in amorphous silicon is larger than in crystal silicon.. This fact will result in diffusion of Fe atoms to surface before precipitation of β-FeSi2. In the next experiment, the low temperature solid phase epitaxy will be conducted before annealing at 830oC for 18 hours. Likewise, the location of β-FeSi2 precipitates will be observed.
We also synthesized β-FeSi2 precipitates by co-sputtering. Samples of IBS always produce defects like dislocation loops. Presentation of defects is also harmful to the luminescence of β-FeSi2 precipitates. Ion gun will be used to co-sputtering Fe-Si atoms onto Si(001) wafer. In order to avoid oxidation of Fe and Si atoms, a thickness of about 50nm Germanium layer will be capped on our sample. After different annealing process, the retardation of transformation of Fe silicide by presentation of Ge layer will be observed.
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Lin, Cheng-yi, and 林承毅. "Effect of solid solution and annealing on microstructure of 13Cr2Ni2Mo stainless steel." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76mn5y.
Testo completoAbstract (sommario):
碩士<br>國立高雄大學<br>化學工程及材料工程學系碩士班<br>103<br>This study is focused on a 13Cr2Ni2Mo stainless steel use as screws manufacturing. We want to find the best heat treatment parameters for manufacturing, by analysising it’s microstructure and hardness.
The first part of my experiment is solid solution heat treatment.In this stage,the microstructure is martensite as a base phase with some δ ferrite phase. When temperature of solid solution heat treatment is 1100 ℃,and temperature holding time is less than 30 minutes, there is still B-rich Mo-rich phase undissolved back to base; The fraction of δ ferrite phases are positive related with temperature and holding time, but the fraction of the ferrite is negative related with hardness in 1100℃~ 1200℃.
The second part, we want to soften the stainless steel. So we anneal it by 640 ℃ ~ 790 ℃.We found that when annealing temperature higher than 690℃,there are M23C6 and M23 (C,B)6 precipitated.When temperature higher than 740℃,Laves phase is precipitated on δ ferrite grain boundaries. When the annealing temperature above 740 ℃ ,it comes to the (α + γ) two-phase region. γ phase is positive related with the annealing temperature and the annealing holding time. The γ-phase transform to martensite at room temperature, and martensite make hardness upgrade. So, to soften 13Cr2Ni2Mo stainless steel should avoid the annealing temperature exceeds (α + γ) two-phase zone.
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Chang, Chia-Yuan, and 張佳媛. "Influence of Annealing on the Microstructure and Properties of ATO Thin Films." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/60097749448691048161.
Testo completoAbstract (sommario):
碩士<br>國立成功大學<br>材料科學及工程學系<br>89<br>Antinomy doped tin oxide (ATO) films have been extensively used in electronic and opto-electronic applications because of their high carrier concentration, low electrical resistivity and high transmission in the visible range. In this study, ATO films were deposited on corning glass 1737F by RF magnetron reactive sputtering with different oxygen partial pressures. The effects of annealing temperature and atmosphere on the composition, microstructure, surface morphology, conductivity and optical properties of ATO films were investigated.
The results of conductivity measurements revealed that the resistivity decrease initially and then increase again with oxygen flow rate. After thermal annealing, the resistivity became one to two orders of magnitude lower than those observed in as-deposited films. The decrease in resistivity with annealing temperature is because of the increase in carrier mobility and concentration.
Results also showed that films after annealing at 500℃ in nitrogen, a low resistivity of 3.92×10-3Ω-cm and high transparency of 80% were obtained. This can be explained by the desorption of oxygen from the grain boundaries. In addition, the absorption edge moves toward lower wavelength after annealing.
ABSTRACT.......... III
表目錄............ VI
圖目錄............ VII
第一章、緒論...... 1
1.1 前言.......... 1
1.2 研究重點...... 4
第二章、理論基礎..5
2.1 濺鍍理論...... 5
2.2 射頻電源的自偏壓現象... 10
2.3 鍍層的成核.... 12
2.4 氧化銻錫（ATO）薄膜的特性........16
第三章、實驗方法與步驟..... 24
3.1 實驗流程...... 24
3.2實驗前準備..... 24
3.2.1基材前處理... 24
3.3 實驗設備...... 27
3.4 濺鍍步驟與條件......... 27
3.5 退火處理...... 27
3.6 鍍層分析及性質測試..... 32
3.6.1 測量濺鍍速率 .........32
3.6.2 電性量測.... 32
3.6.3 光學性質量測......... 35
3.6.4 微結構觀察........... 35
3.6.5 X-ray繞射分析........ 35
3.6.6 AES成份分析.......... 36
第四章、結果與討論......... 37
4.1 反應濺鍍速率........... 37
4.2 組成與微結構分析....... 40
4.2.1 組成分析.... 40
4.2.2 X-ray繞射分析........ 45
4.2.3 微結構...... 51
4.3 電性.......... 59
4.4 光學性質...... 71
第五章、結論...... 75
未來研究方向...... 76
參考文獻.......... 77
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Chang, I.-Cheng, та 張以澄. "Studies on Microstructure of Annealing Twin and Deformation Twin in α-brass". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/42264836588559211385.
Testo completoAbstract (sommario):
碩士<br>國立臺灣大學<br>材料科學與工程學研究所<br>100<br>The term of twin in materials represents two crystals with a mirror symmetry relationship. In this thesis, two types of twins will be discussed: one is the annealing twin, and the other is the deformation twin. The formation of annealing twin, as a result of annealing treatment, can be traced back to growth accidents or stacking faults during recrystallization. The deformation twin, on the other hand, is the accommodation to the deformation in matrix owing to the energy minimums. Additionally, some previous studies show that not only in BCC materials but also in FCC materials do deformation twins exist. Some conceivable models and mechanisms will be presented for the formation of annealing twins and deformation twins.
The twin boundary, formed by Shockley partial dislocations and stacking faults, is believed to enhance the mechanical property of materials because it can obstruct the movement of dislocations; therefore, the interaction of them and the incoming dislocations are noticeable. However, not every twin boundary will hinder the dislocation; unlike other strengthening method, the existence of twin boundary will improve the ductility. Some of dislocations may cross-slip at the twin boundary, and thus the ductility is maintained. One of the trace of cross-slipping is the ledge of twin. When dislocation dissociates into Shockley partials, only part of incoherent twin boundary can glide continuously, while the other part stops and forms a “step” on boundary. In this thesis, the morphology of annealing twin, deformation twin, the ledge, cross-slipping will be shown by optical microscopy and transmission electron microscopy.
Besides, the orientation of annealing twins will be manifested by EBSD, and the identification of misorientation will be identified by orientation matrices. The result of EBSD will be used in the hardness test, which considers the effect of twin boundary in different orientation.
49
Chen, Y. H., and 陳雅琳. "Effect of Annealing on the Microstructure and Properties of Al2O3/Cu/Al2O3 Multilayers." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/51553785563453823399.
Testo completoAbstract (sommario):
碩士<br>國立中興大學<br>材料工程學研究所<br>93<br>This research focuses on the interfacial reactions between aluminum oxide and copper thin films in the Al2O3/Cu/Al2O3 multilayers under different atmospheres. Firstly, the Al2O3/Cu/Al2O3 multilayers were prepared by a dual ion beam deposition technique on Si wafer. Subsequently, the multilayers were annealed at 600~1000℃ for 4 hours under vacuum and argon atmospheres. The microstructural change and morphology of the multilayers after annealing under vacuum and argon atmospheres were analyzed by X-ray diffraction (XRD), field emission scanning electron microscropy (FESEM), transmission electron microscopy (TEM), and atmoic force microscopy (AFM).
The changes of the multilayer’s properties after annealing under vacuum and argon atmospheres were investigated by thermodynamics and kinetics methods. No significantly change on the microstructure of the multilayers was observed after annealing at 600 and 800 ℃under vacuum. This could be attributed to the thermodynamic stability under vacuum ,and no reaction occurred between aluminum oxide films and copper films. However, copper layer was melted and became many copper balls sandwiched by two aluminum oxide films after the multilayers were annealed at 1000℃under vacuum.
The copper layer was oxidized to CuO in the multilayers after annealing at 600 ℃ under argon atmosphere. Most of CuO were not reacted with Al2O3 and there was a small amount of CuAlO2 and CuAl2O4 observed near aluminum oxide layer. The multilayers become mixing layers consisting of CuO, CuAlO2 and CuAl2O4 after annealing at 800 and 1000 ℃ under argon atmosphere.
50
Tzung-LunLo and 羅宗倫. "Nanoindentation Behaviour and Microstructure of ZnO/GaAs Thin Film with and without Annealing." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nv6mm6.
Testo completo