Dissertations / Theses on the topic 'Age hardening'
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Kent, Damon. "Age hardening of sintered Al-Cu-Mg-Si-Sn alloys /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17893.pdf.
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Johnson, Lars. "Nanostructuring and Age Hardening in TiSCN, ZrAlN, and TiAlN Thin Films." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56221.
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This thesis explores nanostructuring in TiSiCN, ZrAlN, and TiAlN thin films deposited by cathodic arc evaporation onto cemented carbide substrates, with intended applications for cutting tools. The three systems were found to exhibit age hardening upon annealing, by different mechanisms, into the superhard regime (≥30 GPa), as determined by a combination of electron microscopy, X-ray diffraction, atom probe tomography, erda, and nanoindentation tech- niques. TiSiCN forms nanocomposite films during growth by virtue of Si segregation to the surface of TiCN nanocrystallites while simultaneously pro- moting renucleation. Thus, the common columnar microstructure of TiCN and low-Si-content (≤5 at. %) TiSiN-films is replaced by a “feather-like” nanos- tructure in high-Si-content (≥10 at. %) TiSiCN films. The presence of C promotes the formation of this structure, and results in an accelerated age hardening beginning at temperatures as low as 700 °C. The thermal stability of the TiSiCN films is, however, decreased compared to the TiSiN system by the loss of Si and interdiffusion of substrate species; C was found to ex- acerbate these processes, which became active at 900 °C. The ZrAlN system forms a two-phase nanostructure during growth consisting of cubic ZrAlN and wurtzite ZrAlN. Upon annealing to 1100 °C, the c-Zr(Al)N portion of the films recovers and semicoherent brick-like w-(Zr)AlN structures are formed. Age hardening by 36 % was obtained before overageing sets in at 1200 °C. As-deposited and annealed solid solution Ti0.33Al0.67N thin films were characterized for the first time by atom probe tomography. The as-deposited film was found to be at the very initial stage of spinodal decomposition, which continued during annealing of the film at 900 °C for 2 h. N preferentially segregates to Al-rich domains in the annealed sample, causing a compositional variation between Ti-rich and Al-rich domains, to maintain the stoichiometry for the developing AlN phase. That effect also compensates for some of the coherency strain formed between cubic domains of TiN and AlN. Finally, a possible Kirkendall effect caused by an imbalance in the metal interdiffusion during the spinodal decomposition was discovered.
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Frigaard, Øyvind. "A process model for friction stir welding of age hardening aluminium alloys." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 1999. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1759.
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Esarey, John Gilbert. "Continuous measurement by eddy current methods of age hardening in aluminum alloys." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23592.
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Approved for public release; distribution is unlimitedMany materials processing operations such as age hardening heat treatments typically involve following predetermined time and temperature schedules to obtain the desired final material properties. The intelligent processing approach is to develop sensors for monitoring of material response to processing operation in real time. As an alloy age hardens its electrical resistivity changes. Hence, the process of aging can be monitored by measuring the change is resistivity relative to that of a non-age hardening material such as fully annealed aluminum. A device using two small, spiral-wound probes was designed to induce eddy currents within the pure aluminum and the aging alloy. The probes were incorporated as elements in an impedance bridge circuit. The bridge unbalance voltage decreased in value over time indicating decreasing relativity during the aging process. The monitoring concept was verified. Refinements such as improved impedance bridge circuitry and probe size/test frequency optimization are needed to unlock its full potential.
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Beverini, Gianluca. "Phase transformations in binary uranium alloys." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292647.
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Nicol, Alison. "Aspects of copper precipitation and irradiation hardening in Fe-Cu alloys." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325841.
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Skoufari-Themistou, Leda. "Impact and yield strength behaviour of age-hardening, low-carbon copper-containing steels." Thesis, City University London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319641.
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Guapuriche, Manuel Antonio Salazar. "Evolution of Electrical Conductivity, Hardness and Strength during Age Hardening of AA 7010." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507650.
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Khalfallah, Ibrahim. "Designing Microstructure through Reverse Peritectoid Phase Transformation in Ni₃Mo Alloy." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78058.
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High-energy ball milling and powder metallurgy methods were used to produce a partially alloyed nickel and molybdenum of γ-Ni₃Mo composition (Ni-25at.%Mo). Milled powders were cold-compacted, sintered/solutionized at 1300°C for 100h sintering followed by quenching. Three transformation studies were performed. First, the intermetallic γ-Ni₃Mo was formed from the supersaturated solution at temperatures ranging between 600°C and 900°C for up to 100h. The 100% stable γ-Ni₃Mo phase was formed at 600°C after 100h, while aging at temperatures ranging between 650°C and 850°C for 25h was not sufficient to complete the transformation. The δ-NiMo phase was observed only at 900°C as cellular and basket strands precipitates.
Second, the reversed peritectoid transformation from γ-Ni₃Mo to α-Ni and δ-NiMo was performed. Supersaturated solid solution samples were first aged at 600C for 100h followed by quenching to form the equilibrium γ-Ni₃Mo phase. After that, the samples were heat treated between 910°C and 1050°C for up to 10h followed by quenching. Regardless of heat-treatment temperature, samples heat-treated for shorter times exhibited small precipitates of δ-NiMo along and within grain boundaries of α-Ni phase, and it coarsened with time. Third, the transformation from the supersaturated solution α-Ni to the peritectoid two-phase region was performed. The samples were aged between 910°C and 1050°C for up to 10h followed by quenching. Precipitates of δ-NiMo were observed in the α-Ni matrix as small particles and then coarsened with aging time. In all three cases, hardness values increased and peaked in a way similar to that of traditional aging, except that the peak occurred much rapidly in the second and third cases. In the first case, hardness increased by about 113.6% due to the development of the new phases, while the hardness increased by 90.5% and 77.2% in the second and third cases, respectively.Master of Science
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James, Robert Bailey. "Resistivity measurement by eddy current methods for real-time monitoring of age hardening in heat treatable alloys." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA311567.
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PRASAD, PRASHANTH. "CHARACTERIZATION OF NEW, CAST, HIGH TEMPERATURE ALUMINUM ALLOYS FOR DIESEL ENGINE APPLICATIONS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148315194.
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PADIAL, ARMANDO G. F. "Caracterizacao microestrutural do aco maraging de grau 400 de resistencia mecanica ultra-elevada." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10998.
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Made available in DSpace on 2014-10-09T12:46:42Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:56:09Z (GMT). No. of bitstreams: 1 07613.pdf: 5555459 bytes, checksum: 0047c9f052248797761d648268e841ba (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Tan, Evren. "The Effect Of Hot-deformation On Mechanical Properties And Age Hardening Characteristics Of Al-mg-si Based Wrought Aluminum Alloys." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607937/index.pdf.
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Microstructural and mechanical characterizations of heat treatable Al-Mg-Si-Cu based wrought aluminum alloys have been studied. The aim of this work was to produce fine grained, high strength alloy by adjusting processing conditions: deformation, solutionizing and aging.
First, primary characterization was carried out via SEM-EDS analyses and tensile tests. Then an extensive experimental study has been carried out on two sets of samples. The first set has been studied to determine the ideal conditions for solutionizing and aging processes by analyzing the variation of hardness with different solutionizing and aging time and temperature. The second set, have first been mechanically deformed by swaging at four different deformations and four different temperatures, then heat treated. The hardness measurements have been carried out before and after solutionizing and also after aging. Finally, recrystallization behavior has been investigated by measuring grain size before and after solutionizing treatment using image analyzer software.
The initial characterizations showed that Mg2Si and complex iron, manganese bearing intermetallics were the primary particles observed in the α
-Al matrix. Nearly 140HB hardness could be obtained with solutionizing at 530°
C and aging at 175°
C for 8 hours which was determined as the optimum treatment for obtaining peak hardness. When shaping (deformation) was concerned
strength loss was the overall outcome of any hot or cold deformation before solutionizing
which was most probably due to the destruction of the initial microstructure. Improvement in the percent elongation was the promising aspect of this application. Strength loss was increased for samples deformed at higher temperatures and higher reductions.
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Marceau, Ross Kevin William. "Design in Light Alloys by Understanding the Solute Clustering Processes During the Early Stages of Age Hardening in Al-Cu-Mg Alloys." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/4008.
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The evolution of atomistic-level nanostructure during the early stages of both standard, high-temperature T6 heat treatment, and low-temperature secondary ageing after interruption of the former (T6I4), has been investigated in rapid hardening Al-Cu-Mg alloys using a variety of microscopy and microanalytical techniques, including transmission electron microscopy (TEM), positron annihilation spectroscopy (PAS) and atom probe tomography (APT). In order to carry out this objective, quantitative data-analysis methods were developed with respect to new cluster-finding algorithms, specifically designed for use with three-dimensional APT data. Prior to this detailed characterisation work, the actual thermal impact from both heat treatment and quenching of small, lab-scale specimens was determined through correlation of both experimental results and calculations that modelled the heat transfer conditions using the lumped capacitance method. Subsequently, the maximum diffusion distance by random walk of the solute atoms was calculated for these periods, bearing significance on the propensity for these atoms to have the ability to cluster together, rather than segregate to the dislocation loops in the microstructure, which have a relatively larger interspacing distance. Age-hardening curves for the Al-1.1Cu-xMg (x = 0, 0.2, 0.5, 0.75, 1.0, 1.7 at.%) alloys at 150ºC show that the rapid hardening phenomenon (RHP) exists for Mg compositions ≥ 0.5Mg. Given that zone-like precipitate structures were unable to be detected by TEM or APT during the early stages of ageing at 150ºC, and that statistically significant dispersions of clusters were found in the APT data after ageing for 60 s, the RHP is attributed to these clustering reactions. Identification of clusters in the APT data has been achieved using the core-linkage algorithm and they have been found to be quite small, containing only a few atoms up to a couple of tens of atoms. The RHP is governed by some critical number density of both Mg clusters and Cu-Mg co-clusters of a critical size, whereas Cu clusters do not contribute significantly to the hardening mechanism. Significance testing indicates that Mg clusters are more significant at smaller clusters sizes and Cu-Mg co-clusters more important at larger cluster sizes. Hardness results also confirm the existence of rapid early hardening during secondary ageing at 65ºC in Al-1.1Cu-1.7Mg. The mechanism of secondary rapid hardening involves a combination of both secondary clustering from solute (mainly Mg atoms) residual in solution, and pre-existing amorphous primary clusters that have slower growth kinetics at the lower secondary ageing temperature. The latter occurs mainly by vacancy-assisted diffusion of Mg atoms as evidenced by the gradual increase of the Mg:Cu ratio of co-clusters. From an alloy design point of view it is important to fully understand the solute distribution in the microstructure to be able to subsequently optimise the configuration for enhanced material properties. The change in dispersion of solute atoms during ageing was determined by combining calculations of % vacancy-solute associations with detailed measurements of the dislocation loops to estimate the solute distribution within the microstructure. The implication of the balance of solute atoms segregated to the loops compared with that in the matrix is then discussed in the context of hardnening mechanisms.
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Marceau, Ross Kevin William. "Design in Light Alloys by Understanding the Solute Clustering Processes During the Early Stages of Age Hardening in Al-Cu-Mg Alloys." University of Sydney, 2008. http://hdl.handle.net/2123/4008.
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Doctor of Philosophy (PhD)The evolution of atomistic-level nanostructure during the early stages of both standard, high-temperature T6 heat treatment, and low-temperature secondary ageing after interruption of the former (T6I4), has been investigated in rapid hardening Al-Cu-Mg alloys using a variety of microscopy and microanalytical techniques, including transmission electron microscopy (TEM), positron annihilation spectroscopy (PAS) and atom probe tomography (APT). In order to carry out this objective, quantitative data-analysis methods were developed with respect to new cluster-finding algorithms, specifically designed for use with three-dimensional APT data. Prior to this detailed characterisation work, the actual thermal impact from both heat treatment and quenching of small, lab-scale specimens was determined through correlation of both experimental results and calculations that modelled the heat transfer conditions using the lumped capacitance method. Subsequently, the maximum diffusion distance by random walk of the solute atoms was calculated for these periods, bearing significance on the propensity for these atoms to have the ability to cluster together, rather than segregate to the dislocation loops in the microstructure, which have a relatively larger interspacing distance. Age-hardening curves for the Al-1.1Cu-xMg (x = 0, 0.2, 0.5, 0.75, 1.0, 1.7 at.%) alloys at 150ºC show that the rapid hardening phenomenon (RHP) exists for Mg compositions ≥ 0.5Mg. Given that zone-like precipitate structures were unable to be detected by TEM or APT during the early stages of ageing at 150ºC, and that statistically significant dispersions of clusters were found in the APT data after ageing for 60 s, the RHP is attributed to these clustering reactions. Identification of clusters in the APT data has been achieved using the core-linkage algorithm and they have been found to be quite small, containing only a few atoms up to a couple of tens of atoms. The RHP is governed by some critical number density of both Mg clusters and Cu-Mg co-clusters of a critical size, whereas Cu clusters do not contribute significantly to the hardening mechanism. Significance testing indicates that Mg clusters are more significant at smaller clusters sizes and Cu-Mg co-clusters more important at larger cluster sizes. Hardness results also confirm the existence of rapid early hardening during secondary ageing at 65ºC in Al-1.1Cu-1.7Mg. The mechanism of secondary rapid hardening involves a combination of both secondary clustering from solute (mainly Mg atoms) residual in solution, and pre-existing amorphous primary clusters that have slower growth kinetics at the lower secondary ageing temperature. The latter occurs mainly by vacancy-assisted diffusion of Mg atoms as evidenced by the gradual increase of the Mg:Cu ratio of co-clusters. From an alloy design point of view it is important to fully understand the solute distribution in the microstructure to be able to subsequently optimise the configuration for enhanced material properties. The change in dispersion of solute atoms during ageing was determined by combining calculations of % vacancy-solute associations with detailed measurements of the dislocation loops to estimate the solute distribution within the microstructure. The implication of the balance of solute atoms segregated to the loops compared with that in the matrix is then discussed in the context of hardnening mechanisms.
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Marceau, Ross K. W. "Design in light alloys by understanding solute clustering processes during the early stages of age hardening in Al-Cu-Mg alloys." Connect to full text, 2008. http://ses.library.usyd.edu.au/handle/2123/4008.
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Thesis (Ph. D.)--University of Sydney, 2008.Title from title screen (viewed Jan 07, 2009). Includes two published articles co-authored with others. Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Australina Key Centre for Microscopy and Microanalysis, Electron Microscope Unit, Faculty of Science. Includes bibliographical references. Also available in print form.
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Forsén, Rikard, M. P. Johansson, Magnus Odén, and Naureen Ghafoor. "Effects of Ti alloying of AlCrN coatings on thermal stability and oxidation resistance." Linköpings universitet, Nanostrukturerade material, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-93255.
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Quaternary cubic (TixCr1 − xAl~ 0.60)1 N1 coatings with 0 < x < 0.33 have been grown using reactive cathodic arc evaporation. When adding Ti the hardness was retained after annealing up to 1100 °C which is a dramatic improvement compared to CrAlN coatings. The coatings showed an age hardening process caused by spinodal decomposition into coherent TiCr- and Al-rich cubic TiCrAlN domains and the formation of hexagonal AlN precipitates and cubic TiCrN domains in the vicinity of the grain boundaries. The improved hardness was attributed to the stabilization of the cubic structure suppressing the formation and growth of hexagonal AlN. Furthermore, the presence of Ti atoms generated incoherent nanometer-sized crystallites within the hexagonal AlN precipitates disrupting the hexagonal lattice during the coarsening process. The addition of Ti promoted the formation of a TiO2 layer over Al2O3 resulting in a lower oxidation resistance. However, by tuning the composition it is possible to design coatings to have both good oxidation resistance and good high temperature mechanical stability.Funding Agencies|SSF project Designed multicomponent coatings, MultiFilms||
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Syed, Muhammad Bilal. "Thermal Stability of Arc Evaporated ZrCrAlN." Thesis, Linköpings universitet, Nanostrukturerade material, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-84769.
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This research explores the thermal stability of ZrCrAlN material system. For this purpose fourteen different compositions of ZrCrAlN coatings were deposited onto tungsten carbide substrates by using reactive cathodic arc evaporation. These compositions were further annealed at 800oC, 900oC, 1000oC and 1100oC temperatures. EDS was employed to specify the compositions. The crystal structure of the coatings were analysed by XRD, and the hardness of these coatings was determined by Nanoindentation. The experimental findings reported a significant age hardening of Zr0.16Cr0.12Al0.72N and a delayed h-AlN formation in Zr0.07Cr0.40Al0.52N. ZrCrAlN was thus proved to be thermally stable.Multifilms,A4:2 Growth and characterization of Multicomponent Nitrides by Magnetron Sputtering and Arc evaporation
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CHEN, DONGSHENG. "酸化物分散強化フェライト鋼における鉄/クロム相分離挙動." Kyoto University, 2015. http://hdl.handle.net/2433/199548.
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CHEN, DONGSHENG. "Iron/Chromium Phase Decomposition Behavior in Oxide Dispersion Strengthened Ferritic Steels." Kyoto University, 2015. http://hdl.handle.net/2433/199417.
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Hwang, Junyeon. "Characterization and Mechanical Properties of Nanoscale Precipitates in Modified Al-Si-Cu Alloys Using Transmission Electron Microscopy and 3D Atom Probe Tomography." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3661/.
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Among the commercial aluminum alloys, aluminum 319 (Al-7wt%Si-4wt%Cu) type alloys are popularly used in automobile engine parts. These alloys have good casting characteristics and excellent mechanical properties resulting from a suitable heat treatment. To get a high strength in the 319 type alloys, grain refining, reducing the porosity, solid solution hardening, and precipitation hardening are preferred. All experimental variables such as solidification condition, composition, and heat treatment are influence on the precipitation behavior; however, precipitation hardening is the most significant because excess alloying elements from supersaturated solid solution form fine particles which act as obstacles to dislocation movement. The challenges of the 319 type alloys arise due to small size of precipitate and complex aging response caused by multi components. It is important to determine the chemical composition, crystal structure, and orientation relationship as well as precipitate morphology in order to understand the precipitation behavior and strengthening mechanism. In this study, the mechanical properties and microstructure were investigated using transmission electron microscopy and three dimensional atom probe tomography. The Mn and Mg effects on the microstructure and mechanical properties are discussed with crystallographic study on the iron intermetallic phases. The microstructural evolution and nucleation study on the precipitates in the low-Si 319 type aluminum alloys are also presented with sample preparation and analysis condition of TEM and 3DAP tomography.
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Kovarik, Libor. "Microstructural study and modeling of metastable phases and their effect on strenghthening [sic] in Al-Mg-Cu-Si alloying system." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1149006665.
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Sasaki, Cassiano Massakazu. "Desempenho operacional de um subsolador em função da estrutura, do teor de argila e de água em três latossolos." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-15062005-150804/.
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A rápida evolução tecnológica da silvicultura brasileira, verificada na década de 80, culminou com o sistema de cultivo mínimo do solo, implantado em grande escala a partir do início da década de 90. Levantamentos recentes junto a empresas florestadoras de expressão nacional, indicaram que cerca de 77% da área plantada é realizada no sistema de cultivo mínimo do solo. O amplo emprego do subsolador no cultivo mínimo e a falta de estudos científicos no projeto, o empirismo associado à operação e a falta de informações sobre a interação entre o teor de água e o tipo de solo subsolado motivaram a condução do presente estudo, cujos objetivos foram: (i) avaliar o desempenho operacional de um subsolador com haste parabólica em função da estrutura, do teor de argila e de água em três Latossolos, (ii) avaliar o grau de mobilização do solo em função de teores crescentes de argila e de água, (iii) avaliar a duração do efeito desagregador da subsolagem e a relação entre a área mobilizada de solo e o tempo póssubsolagem e, (iv) estabelecer um intervalo ideal de umidade para a subsolagem, em função da mobilização e da densidade máxima do solo. As pesquisas foram desenvolvidas em um Latossolo Vermelho Distrófico textura média (LVd-1), um Latossolo Vermelho Distrófico textura argilosa (LVd-2) e um Latossolo Vermelho Distrófico textura muito argilosa (LVd-3). A avaliação do desempenho operacional do subsolador foi realizada por meio dos parâmetros volume mobilizado de solo (VMS), profundidade efetiva de trabalho (PET), largura efetiva de trabalho (LET), velocidade média de deslocamento (VMD), capacidade teórica de trabalho (CTT) e rendimento (R). O grau de mobilização dos solos e o tempo de duração dos efeitos da subsolagem foram avaliados por meio da área mobilizada de solo (AMS), mensurada em três datas: logo após a subsolagem, 12 e 24 meses pós-subsolagem. O intervalo ideal de umidade para a subsolagem foi baseado na AMS e no teste de Proctor normal. A maioria dos parâmetros usados na avaliação do desempenho operacional indicou que teores de água mais baixos melhoram o desempenho do subsolador. Nos solos com estrutura em blocos, LVd-2, e com alto teor de argila, LVd-3, foram obtidos o maior VMS (com o solo mais seco) e o menor R (com o solo mais úmido); esses atributos também provocaram maior readensamento das partículas de solo no sulco de preparo, diminuindo o efeito desagregador da subsolagem mais rapidamente. Tanto no LVd-2, como no LVd-3, praticamente a metade da área mobilizada inicial foi modificada (56 e 49%, respectivamente). O LVd-1 foi o solo que apresentou a menor resposta aos tratamentos, em função de sua capacidade de suporte ser mais estável que a dos outros Latossolos estudados. O LVd-1 apresentou melhores condições de ser subsolado entre os teores de água de 0,07 a 0,13 cm3 cm-3, o LVd-3, entre 0,14 a 0,27 cm3 cm-3 e, o LVd-2, apresentou a amplitude de subsolagem mais restrita, entre 0,12 a 0,19 cm3 cm-3.The fast technological development of the Brazilian silviculture, during the 80s decade, culminated with the soil minimum cultivation system, established in large degree from the beginning of the 90s decade. Recent surveys in expressive Brazilian forest companies, indicated that about 77% of the planted area is accomplish under the soil minimum cultivation system. The large use of the subsoiler in the minimum cultivation, the empiricism associated to the operation and the lack of information about the interaction between the moisture content and the subsoiled soil motivated the present study, which objectives were: (i) evaluate the operational performance of a subsoiler with parabolic tine as a function of the soil structure, clay and moisture content of three Latosols, (ii) evaluate the soil disturbance degree as a function of the increasing on the clay and moisture content, (iii) evaluate the length of the subsoiling effect on the soil and the relationship between the soil disturbed area and the time after the subsoiling and, (iv) settle an ideal water interval to the subsoiling, as a function of the soil disturbance and the maximum bulk density. The researchers were developed in a sandy clay loam dystrophic Red Latosol (LVd-1), a clay dystrophic Red Latosol with kaolinit (LVd-2) and a clay dystrophic Red Latosol (LVd-3). The operational performance evaluation was realized by the parameters soil disturbed volume (SDV), work depth (WD), work width (WW), average speed (AS), theoretical work capacity (TWC) and efficiency (E). The soils disturbance degree and the length of the subsoiling effects were evaluated by the soil disturbed area (SDA), which was measured three times: after the subsoiling, 12 and 24 months after the subsoiling. The ideal water interval of the subsoiling was based upon the SDA and the normal Proctors test. Most of the parameters used to the operational performance evaluation indicated that lower moisture contents improve the subsoiler performance. The soils with structure in blocks, LVd-2, and high clay content, LVd-3, presented higher SDV (when the soils were dryer) and lower E (when the soils were damper); these characteristics provoked high age-hardening of the soil particles either, decreasing the subsoiling effect faster. Almost half of the original soil disturbed area was modified in the LVd-2 and in the LVd-3 (56 and 49%, respectively). The LVd-1 was the soil that presented the lower effect to the treatments, as a function of its high stability. The LVd-1 presented better conditions to be subsoiled between the moisture contents of 0,07 and 0,13 cm3 cm-3, the LVd-3, between 0,14 and 0,27 cm3 cm-3 and, the LVd-2, presented the lower subsoiling water range, between 0,12 and 0,19 cm3 cm-3.
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Tort, Morgan. "The effects of severe plastic deformation on an age hardenable Al-2.5Cu-1.5Mg alloy." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22578.
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Les effets du pressage à canaux égaux (ECAP), un procédé de déformation plastique sévère, ont été examinés dans un alliage Al-2.5Cu-1.5Mg (pourcentage en masse) prône à être durci par traitement thermique et précipitant dans la région α + S. Une multitude de techniques microscopiques, calorimétriques et analytiques ont été utilisés pour caractériser et quantifier les microstructures, incluant la diffraction Kikuchi, la microscopie électronique en transmission, la calorimétrie différentielle à balayage et la sonde atomique tomographique. Quatre différents traitements thermiques initiaux ont été réalisés pour créer quatre microstructures différentes, contenant soit aucun précipités, des clusters Cu-Mg ou/et des composés intermétalliques Al2CuMg. Chaque spécimen a été soumis au procédé ECAP à température ambiante et les effets correspondants sur la microstructure et les propriétés mécaniques ont été analysés. Des expériences en compression pour de petite déformation (inférieures à 7%) ont aussi été entreprises sur les échantillons trempés pour étudier les effets de la compression sur la formation des clusters. Après la trempe et la compression, des clusters Cu-Mg ont été trouvés dans la matrice et il a été élucidé que la formation des clusters était déclenchée par la compression. La fraction volumique des clusters est corrélée directement par la déformation appliquée : plus la déformation est importante, plus la fraction volumique des clusters est importante. Après ECAP, la microstructure est constituée de longues bandes nanocristallines séparée par de gros grains non-déformés pour les échantillons contenant seulement des clusters avant la déformation, tandis que la présence de phase S, avant ECAP, conduit à des microstructures constituées de zones à gros grains et de zones à grains raffinés, distribués d’une façon homogène à travers les échantillons. Bien que les spécimens présentaient clairement des microstructures différentes après ECAP, impliquant que différents mécanismes de renforcement entre en jeux, la limite élastique se situait au-delà de 500 MPa. La limite élastique des échantillons fabriqués par ECAP a été modélisée en superposant les différents mécanismes de renforcement et en saisissant les paramètres microstructurels venant de la caractérisation dans le modèle. Il a été démontré qu’une très bonne corrélation existait entre les limites élastiques provenant du modèle et celles expérimentalesThe effects of equal channel angular pressing (ECAP), a severe plastic deformation (SPD) technique, were investigated in an age hardenable Al-2.5Cu-1.5Mg (weight percent (wt.%)) alloy precipitating in the α + S phase field. A variety of microscopy, calorimetry and analytical techniques were employed to characterize and quantify the microstructure, including transmission kikuchi diffraction (TKD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and atom probe tomography (APT). Four different initial heat-treatments were conducted to achieve four different microstructures, containing either no precipitates, Cu-Mg clusters or/and Al2CuMg intermetallics. Each specimen was subjected to ECAP at room temperature and the related effects on the microstructure and mechanical properties were analysed. Compression experiments for small strains (less than 7%) were also undertaken on the as-quenched samples to investigate the effects of compression on the formation of clusters.After quenching and compression, Cu-Mg clusters were found in the matrix and it was elucidated that the formation of clusters was triggered by pressing. The volume fraction of clusters was found to be correlated to the strain applied: the higher the strain, the higher the volume fraction.After ECAP, the microstructure was constituted of long nanocrystalline bands separated by large undeformed grains for the samples containing only clusters before deformation, while the presence of S phase, prior to ECAP, lead to microstructures constituted of both coarse and refined zones distributed homogeneously throughout the sample. Although the samples presented clearly different microstructures after ECAP, implying that different strengthening mechanisms were active, the yield strength was found to lie above 500 MPa. The yield strength of the ECAP processed samples was modelled by superposing the different strengthening mechanisms altogether and by inputting the microstructural parameters coming from characterisation in the model. It was demonstrated that a very good correlation existed between the modelled and experimental yield strength values
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Balan, Alexandre. "Modélisation isotherme et anisotherme de la limite d'élasticité précipitation-dépendante de l'Inconel 718." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI003/document.
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Ce manuscrit de thèse présente les résultats de travaux concernant les effets des transitoires thermiques sur la précipitation des phases intermétalliques dans le superalliage base nickel Inconel 718® et les conséquences de cette précipitation sur les propriétés mécaniques de cet alliage. Ces travaux se concentrent sur une approche couplée capable de décrire l’évolution de la précipitation de la phase γ'' et ses conséquences sur la limite d’élasticité de l’Inconel 718®. L’état de précipitation est modélisé grâce à l’implémentation des équations de la théorie classique de germination et de croissance, modifiées afin de prendre en compte la géométrie en plaquette des précipités γ''. Ce modèle de précipitation est ensuite validé par des données expérimentales issues de la littérature mais également d’observations au microscope électronique en transmission et d’essais de diffusion de neutrons aux petits angles. La distribution de taille de la phase γ'' ainsi simulée est utilisée comme donnée d’entrée d’un modèle de prédiction de la limite d’élasticité précipitation-dépendant. Ces limites d’élasticité simulées sont enfin comparées à des résultats expérimentaux issus d’essais de traction. Une maquette de soudage a ensuite été réalisée afin de tester le modèle de prévision de limite d’élasticité pour des transitoires thermiques, dans un cas industrielThis thesis manuscript presents the results of work concerning the effects of thermal transients on the precipitation of intermetallic phases in the nickel-based superalloy Inconel 718® and the consequences of this precipitation on the mechanical properties of this alloy. This work focuses on a coupled approach capable of describing the evolution of the precipitation of the γ'' phase and its consequences on the yield strength of the Inconel 718®. The precipitation state is modeled thanks to the implementation of the equations of the classical germination and growth theory, modified to take into account the platelet geometry of the γ'' precipitates. This precipitation model is then validated by experimental data from the literature but also from transmission electron microscope observations and small angle neutron scattering tests. The size distribution of the γ'' phase thus simulated is used as the input data of a model for predicting the precipitation-dependent elasticity limit. These simulated elasticity limits are finally compared with experimental results from tensile tests. A welding model was then made to test the elastic yield prediction model for thermal transients in an industrial case
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Ibrahim, Hamdy Ibrahim. "Bioresorbable Magnesium-Based Bone Fixation Hardware: Alloy Design, Post-Fabrication Heat Treatment, Coating, and Modeling." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1503678544356525.
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Braik, Abdullah Mousa Darwish. "RELIABILITY AND COST ANALYSIS OF POWER DISTRIBUTION SYSTEMS SUBJECTED TO TORNADO HAZARD." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1543584694806575.
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Meyruey, Gwenaëlle. "Caractérisation et modélisation du vieillissement thermique d’un composite à base d’alliage d’Aluminium." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI092.
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Les composites à matrice métallique ont été développés dans les années 60 initialement pour les besoins de l’industrie aérospatiale. De nos jours, les alliages d’Aluminium à durcissement structural sont souvent combinés à des particules céramiques afin d’atteindre des propriétés de résistance élevées, maintenues à haute température, tout en conservant la légèreté de l’alliage, pour un coût faible. Cependant, l’utilisation de ces alliages nécessite une bonne connaissance des transformations microstructurales ayant lieu lorsqu’ils sont soumis à certaines conditions de température puisque des phénomènes de précipitation ont lieu et impactent les propriétés de résistance mécanique du matériau. De plus, la présence du renfort, induit des modifications microstructurales majeures et notamment lors des phénomènes de précipitation de la matrice. Ainsi, ces travaux de thèse portent sur un alliage d’Aluminium à durcissement structural de la série 6xxx qui, durant son utilisation, peut être confronté à des températures comprises entre 100°C et 350°C, et ayant une séquence de précipitation complexifiée par la présence de Silicium en excès et de particules de renfort céramiques. Les objectifs visés par ces travaux sont alors : 1) De décrire l’évolution microstructurale de l’alliage d’AlMgSi à excès de Silicium étudié, avec et sans particules céramiques. Ensuite, l’évolution de la résistance mécanique a été caractérisée à partir d’un état T6 lors de traitements isothermes, 2) De prédire ces évolutions microstructurales et les propriétés mécaniques qui en découlent par des modèles à base physique. La précipitation des principales phases de l'alliage étudié a pu être prédite grâce un modèle à champ moyen basé sur des lois classiques de germination-croissance et par une approche par classes de type KWN, en tenant compte : 1) de la compétition entre la phase cohérente et semi-cohérente, 2) d'une morphologie en bâtonnet avec un rapport de forme variable et propre à la phase modélisée. Ce modèle a permis, de tracer le diagramme Temps-Température-Transformation de l’alliage et du composite tout en tenant compte de l'accélération des cinétiques de précipitation en présence de renfort et attribuée à la forte densité de dislocations. Pour finir, 2 méthodes de prédiction des propriétés mécaniques ont été confrontées : 1) Une approche empirique de type JMAK (Johnson-Mehl-Avrami-Kolmogorov), 2) une approche à base physique. Malgré une prédiction proche des résultats expérimentaux par l'approche JMAK, cette méthode ne permet pas de remonter aux mécanismes physiques à l’origine des variations observées. Ainsi, l'approche à base physique basée sur le modèle de prédiction de la microstructure constitue une alternative prometteuse pour une prédiction plus précise des évolutions de propriétés de résistance mécaniques de ces matériaux même si de nombreuses adaptations restent à faire dans le cas du compositePrecipitation-strengthened alloys as Al-Mg-Si alloys reinforced with ceramic particles are an appropriate alternative for industrial applications. The precipitation sequence in Al-Mg-Si alloys is particularly complex when Silicon is in excess with respect to the Mg2Si composition and it is expected to be modified by the presence of the ceramic reinforcement. This is why, for industrial applications, under certain use conditions, it is fundamental to be able to predict the evolution of the microstructure in the alloy and the consequences on mechanical properties. The present work is devoted to the study of an age-hardenable Al-Mg-Si aluminium alloy which, can be facing temperatures between 100°C and 350°C in use conditions. This material is characterized by a complex precipitation sequence due to Silicon-excess and ceramic particles. The main objectives of the work are the following: 1) To describe how the microstructure evolves in the Al-Mg-Si alloy with silicon excess studied, with or without reinforcement, during a long storage period at a temperature between 100°C and 350°C. Then, it appeared necessary to describe the evolution of the mechanical properties in the same conditions but starting from a T6 state (corresponding to peak aged conditions). 2) To predict these evolutions (microstructure and strength) using an appropriate model. It was highlighted that the high silicon excess in the studied alloy leads to a simultaneous precipitation of several semi-coherent phases. Their precipitation has been predicted thanks to a KWN-type model based on classical nucleation-growth theories, validated by the experiments, and implemented considering: 1) the competitive precipitation between coherent et semi-coherent phases, 2) the rod-shape morphology of precipitates with a variable aspect ratio. This model has been used for the prediction of the Time-Temperature-Transformation diagram of the alloys and its composite considering the acceleration of the precipitation kinetics observed and attributed to the high dislocation density resulting from the presence of ceramic particles. Finally, 2 methods for the mechanical properties prediction have been compared: 1) a JMAK-type empirical approach 2) a physically based approach. The JMAK approach allowed us a quicker and easier prediction of the loss of hardness from the T6 state, for alloy and composite, during isothermal and non-isothermal treatment. Despite a prediction close to the experimental results, this approach cannot give us information about the physical mechanisms responsible for the observed mechanical variations. Then, a physically based approach taking into account the predictions of the precipitation model was used for the yield stress estimation during aging with a micromechanical model. This approach gave encouraging results and could be a powerful tool for the prediction of the strength during industrial use conditions
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Ferris, William F., Terry R. McNelley, and Stephen J. Hales. "The age hardening response of thermomechanically processed Al-Mg-Li alloys." Thesis, 1987. http://hdl.handle.net/10945/22597.
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Chen, Kuo-Chan, and 陳國洲. "A Study on Age-Hardening Characteristics of Squeeze Castδ- Alumina Fiber-Reinforced Al(2024) Composites." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/60907141904950726752.
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碩士國立交通大學
材料科學(工程)研究所
81
Precipitation hardening can influence the mechanical properties of the alumina-reinforced aluminum alloy(2024) composites fabricated by squeeze casting method. Owing to the presence of alumina fibers, the aging behavior of alumina reinforced aluminum alloy is different from aluminum alloy(2024) . Therefore, the condition of heat treatment for aluminum alloy (2024) is not satisfied to alumina-reinforced aluminum alloy (2024) composites. In the present study, we performed investigitions of DSC, microhardness, and observations of TEM to realize the difference of precipitation hardening processing of the two materials. It was found that the aging hardenign response of the matrix alloy in metal matrix composites caused suppression of GP zones forming. The reason is that the fiber- matrix interface can be treated as sinks of quench-in vacancies. In addition, the precipitates of aluminum alloy(2024) are GP zones and S', and that of alumina-reinfoced aluminum alloy(2024) composites is only S'. The precipitation of S' in alumima reinforced aluminum alloy(2024) composites is less than that of aluminum alloy(2024). The precipitation of S' is decreaed with increasing volume fraction of alumina fibers. Therefore, the peak hardness of the matrix of alumina- reinforced aluminum alloy (2024) composites is lower than that of aluminum alloy(2024).
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Hung, Cheng-Hsin, and 洪正欣. "Effect of age hardening by using Mo and Ti in substitution for Al or by adding them in Al0.3CoCrFeNi high entropy alloy." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/29787683934682096889.
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碩士逢甲大學
材料科學所
97
This study discusses the effect of age hardening at 600-1000℃ by using Mo and Ti in substitution for Al or by adding them in an FCC Al0.3CoCrFeNi high entropy alloy. Six alloys represented by Al0.3CoCrFeNi, CoCrFeNiMo0.3, CoCrFeNiTi0.3, Al0.3CoCrFeNiMo0.1, Al0.3CoCrFeNiTi0.1, and Al0.3CoCr FeNiMo0.05Ti0.05 were synthesized. The Al0.3CoCrFeNi alloy reached its maximum hardness at 700℃-144 hrs aging. The strengthening is due to two precipitates of L12 and B2. The CoCrFeNiMo0.3 alloy reached its maximum hardness at 900℃-24 hrs aging in that a large quantity of rich Mo-Cr BCC harder phase (HV 543) was formed. The CoCrFeNiTi0.3 alloy reached the highest hardness (HV 500) in this study at 700℃-144 hrs aging because the maximum amount of Ni-Ti phase was precipitated. The Al0.3CoCrFeNiMo0.1 alloy reached its maximum hardness at 700℃-144 hrs aging because two different types of precipitates were formed: One was a black rod rich Ni-Al phase; the other was a white rod of Cr rich σ phase. The Al0.3CoCrFeNiTi0.1 alloy reached its maximum hardness at 700℃-144 hrs aging because both the amount of rich Ni-Al-Ti phase was increased and a great quantity of rich Ni-Ti phase with B2 structure was precipitated. The Al0.3CoCrFeNiMo0.05Ti0.05 alloy reached its maximum hardness at 700℃-144 hrs aging due to the precipitation of large amount of rich Ni-Ti phase and σ phase. The hardness of the as-cast Al0.3CoCrFeNi alloy was increased from HV 149 to HV 330 by using Ti in place of Al. Adding Ti in alloy was shown to be more effective in hardening than adding Mo. Either addition of Ti or Mo in Al0.3CoCrFeNi alloy could all raise alloy hardness, but Ti still had stronger hardening effect than Mo. It showed that adding 0.1 molar ratio of Ti in Al0.3CoCrFeNi alloy increased hardness by 83.3% at 700℃-144 hrs aging. Although the hardening effect of adding Mo was inferior to Ti, the precipitation of rich Mo-Cr phase could expand the age hardening effect up to 1000℃.