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1
Coulter, Robert A. "Alloying effects on high temperature deformation behavior of nickel aluminide intermetallics". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1382.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 94 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 88-89).
2
Jamison, Jay Dee. "Modeling of thermal and mechanical effects during friction stir processing of nickel-aluminum bronze". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FJamison.pdf.
Testo completo
3
Rosemark, Brian P. "Friction stir processing parameters and property distributions in cast nickel aluminum bronze". Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FRosemark.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2006.Thesis Advisor(s): Terry R. McNelley, Srinivasan Swaminathan. "December 2006." Includes bibliographical references (p. 49-50). Also available in print.
4
Williams, Robert A. "A microstructural and mechanical property correlation of friction stir processed nickel aluminum bronze". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FWilliams%5FR.pdf.
Testo completo
5
Wall, James J. "Reactive thermomechanical processing of aluminide intermetallics /". free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418074.
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6
Anand, Thangaraj Joseph Sahaya. "Synthesis and microstructure of NixAl1-x (0.5 x 1) thin films". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29533363.
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7
Ternes, J. Kevin. "Visualization and simulation of defect structures in the B2 phase of NiAl". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07212009-040437/.
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8
Afrin, Nasima. "An investigation of deformation behaviour and creep properties of micron sized Ni3Al columns". Thesis, Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37005467.
Testo completo
9
Ma, Longzhou. "Effects of NiAl-[beta] precipitates on crack growth behavior in INCONEL alloy 783". Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2102.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xix, 233 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 223-233).
10
Vailhe, Christophe N. P. "Planar fault energies and dislocation core spreadings in B2 NiAl /". This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12172008-063647/.
Testo completo
11
Dutt, Aniket Kumar. "Microstructural Evolution and Mechanical Response of Materials by Design and Modeling". Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984205/.
Testo completoAbstract (sommario):
Mechanical properties of structural materials are highly correlated to their microstructure. The relationship between microstructure and mechanical properties can be established experimentally. The growing need for structural materials in industry promotes the study of microstructural evolution of materials by design using computational approaches. This thesis presents the microstructural evolution of two different structural materials. The first uses a genetic algorithm approach to study the microstructural evolution of a high-temperature nickel-based oxide-dispersion-strengthened (ODS) alloy. The chosen Ni-20Cr ODS system has nano Y2O3 particles for dispersion strengthening and submicron Al2O3 for composite strengthening. Synergistic effects through the interaction of small dispersoids and large reinforcements improved high-temperature strength. Optimization considered different weight factors on low temperature strength, ductility, and high temperature strength. Simulation revealed optimal size and volume fraction of dispersoids and reinforced particles. Ni-20Cr-based alloys were developed via mechanical alloying for computational optimization and validation. The Ni-20Cr-1.2Y2O3-5Al2O3 alloy exhibited significant reduction in the minimum creep rate (on the order of 10-9 s-1) at 800oC and 100 MPa. The second considers the microstructural evolution of AA 7050 alloy during friction stir welding (FSW). Modeling the FSW process includes thermal, material flow, microstructural and strength modeling. Three-dimensional material flow and heat transfer model was developed for friction stir welding process of AA 7050 alloy to predict thermal histories and extent of deformation. Peak temperature decreases with the decrease in traverse speed at constant advance per revolution, while the increase in tool rotation rate enhances peak temperature. Shear strain is higher than the longitudinal and transverse strain for lower traverse speed and tool rotation rate; whereas for higher traverse speed and tool rotation rate, shear and normal strain acquire similar values. Precipitation distribution simulation using TC-PRISMA predicts the presence of η' and η in the as-received AA 7050-T7451 alloy and mostly η in the friction stir welded AA7050 alloy, which results in the lower predicted strength of friction stir welded alloy. Further, development of modeling assists in process optimization and innovation, and enhances the progression rate. Accelerating the development process requires coupling experimental methods with predictive modeling. The overall purpose of this work was to develop an integrated computational model with predictive capabilities. In the present work, an application tool to predict thermal histories during FSW of AA7050 was developed using COMSOL software.
12
Waqar, Ammar Bin. "Exploration of Electrodeposition of Aluminum-Nickel Alloys and Multilayers in Organic Chloroaluminate Ionic Liquids". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5397.
Testo completoAbstract (sommario):
Aluminum-nickel (Al-Ni) alloys and Al/Ni bilayers were successfully electrodeposited from AlCl3-EMIM-NiCl2 electrolyte at room temperature. Dissolution of NiCl2 was shown to be favorable in Lewis basic (with molar ratio of AlCl3 < 0.5) AlCl3-EMIM solution. The use of electrochemically active Cu working electrode as opposed to inert W induced additional Cu oxidation and dissolution in the cyclic voltammetry scan. The reduction potentials of Al and Ni were found to be ~ – 0.3 and 0.15 V vs. Al/Al3+ respectively. Increasing [NiCl2] in the electrolyte leads to an increase of Ni concentration in the deposited structures. Dense and well-adherent Al-Ni alloys with Ni concentration up to 17.7 at.% were deposited by potential control. XRD analysis revealed that the deposited Al-Ni exhibit a supersaturated fcc crystalline structure. The visual appearance of the deposits ranged from bright silver, dull silver, grey, to black, where the darker shade typically indicated higher Ni content. SEM analysis revealed that the surface morphology of the deposits ranged from nodular to flake-like structures. Al-Ni alloy typically showed nodular morphology with cauliflower structure. Flake structures, which were independent of substrate roughness, were found to develop under pulsed potential deposition with 1:1 duty ratio.
The concentration of Ni in electrodeposited Al-Ni alloys increases nonlinearly with the increase in molarity of NiCl2. Al and Ni contents increase with increasing the time of positive and negative cycle of the pulse respectively. Decreasing the frequency by half resulted in almost double the amount of Ni in the deposited alloy. A smoother substrate increased Ni concentration from 6 to 17.7 at.%. Al/Ni bilayer was successfully deposited in 1.5:1 AlCl3-EMIM containing 0.026 M NiCl2. Deposition of Al on Ni was achieved using constant potential and pulse potential control. The deposition of Ni on Al is complicated since the deposition potential of Ni lies in the vicinity of Al stripping potential thus inducing competition between Ni deposition and Al stripping.
13
Mukunthan, Kannappar. "Properties of ultra fine grain [beta]-CuAlNi strain memory alloys". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26724.
Testo completoAbstract (sommario):
A method has been developed to produce grain sizes as low as 5µm in β-CuAlNi alloys and the effect of grain size on mechanical and strain-memory properties was studied. The thermomechanical treatment procedure involved two. sequential warm working and recrystallization steps at 600° C and 800° C respectively on eutectoid alloys. Three different eutectoid alloys, two with Ms temperature of around 0°C and one with Ms = 220° C were used for the present studies. Even at fine grain sizes, the specimens produced were of single β- phase type without any second phases.
Two-stage characteristic stress-strain curves were obtained for most of the specimens in both the strain memory and pseudoelastic states. It was found that the ultimate tensile strength and strain to failure increased with decreasing grain size according to a Hall-Petch relationship down to a grain size of 5µm with the exception of one alloy. Fracture strengths of 1,200 MPa and fracture strains of 10% could be obtained.
It was found that the major recovery mode, whether pseudoelastic or strain memory, did not have any significant effect on the total recovery obtained. Recovery properties were not affected significantly by decreasing grain size. Approximately 86% recovery could be obtained for an initial applied strain of 5% at a grain size of around 10µm.
Grain refinement increased the fatigue life considerably, possibly due to high ultimate fracture strength and ductile fracture mode. Fatigue life of 275,000 cycles could be obtained for an applied stress of 330 MPa and a steady state strain of 0.6%.
Most of the fractures are due to intergranular-type brittle fracture. At fine grain sizes, transgranular-type brittle fracture and microvoid coalescence-type ductile fracture dominated the fracture mode. Oxygen segregation at grain boundaries is the possible explanation for the different mechanical properties shown by different alloys in the present work by being a major factor in causing intergranular-type fracture.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
14
Cuevas, Assunta Mariela. "Microstructure characterization of friction-stir processed nickel-aluminum bronze through orientation imaging microscopy". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FCuevas.
Testo completo
15
Nandakumar, Nagarajan Nicholson P. S. "Nickel-alumina composites and graded materials by electrophoretic deposition /". *McMaster only, 2005.
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16
Enin-Okut, Edu Owominekaje. "The effect of alumina coatings on the oxidation behavior of nickel-base alloys". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/20226.
Testo completo
17
Vailhé, Christophe N. P. "Planar fault energies and dislocation core spreadings in B2 NiAl". Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/46303.
Testo completoAbstract (sommario):
The lack of ductility of the B2 NiAl alloy stands in the way of promising applications. In an effort to understand the dislocation behavior, computer simulation of the planar faults involved in the core spreadings of <100> and <111> dislocations was carried out. Seven γ-surfaces were computed for different crystallographic planes ({110}, {112}, {123}, {210}, {100}, {111} and {122}). Stable APB's are observed in the {110} and {112} planes but they are deviated from the exact 1/2a<111> position. No other stable planar fault was observed. The dislocation core spreadings are explained by the energy balance among the directions of lowest restoring forces observed in the γ-surfaces. The complete <111> screw dislocation was stable in the simulation. According to the stable APB's, two dissociation reactions of the <111> screw dislocation in the {110} and {112} planes are proposed. The simulation of metastable superpartials shows that the dissociation in the {112} planes is very close to a stable dissociation.Master of Science
18
Taylor, Ryan Chandler. "Effect of a Simulated Butterfly Valve on the Erosion-Corrosion Rate of Nickel Aluminum Bronze Alloys in Highly Turbulent Seawater". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83818.
Testo completoAbstract (sommario):
Nickel aluminum bronze (NAB) alloys are used in naval and maritime applications for their excellent corrosion resistance under the influence of seawater. One application involves the use of a NAB butterfly valve within a NAB fluid line to control fluid flow of seawater. Due to the chaotic environment, the corrosion rate of the NAB tubing downstream from the valve increases significantly. The disc angle at which the valve alters fluid flow causes an increase in the fluid velocity and an increase in the turbulence produced on the downstream side of the valve. These fluid conditions contribute to the increase in the corrosion rate of the NAB piping downstream from the valve. This thesis aims to characterize how the change in the disc angle of the butterfly valve causes a change in the erosion-corrosion rate of NAB downstream from the valve. A butterfly valve is simulated using orifice plates of varying diameters to mimic flow conditions at different disc angles. An orifice plate is a simple device with a hole in its center that is designed to restrict fluid flow across a fluid line. Under the same hydrodynamic conditions, the orifice produces nearly the exact same flow coefficients as the valve. At a volumetric flowrate of 0.00757 m^3/s a total of eight locations found along the liquid/metal interface produced pitting sites. The average passivation layer thickness is also measured.Master of Science
19
Moussa, Sherif Omar Hassan. "Transient processing and characterizatin of advanced materials /". free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3115572.
Testo completo
20
Mekky, Waleed Nicholson P. S. "Fracture toughness of the nickel-alumina laminates by digital image-correlation technique". *McMaster only, 2005.
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21
Xie, Zhao-Yang. "Atomistic simulation of dislocation core structures in B2 NiAl". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40118.
Testo completo
22
Lee, Genevieve W. "Advanced Characterization of Solid-State Dissimilar Material Joints". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492794418438023.
Testo completo
23
Kelly, Sean Christopher. "Shock-compression of Ni-Al nanolayered foils using controlled laser-accelerated thin foil impact". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50288.
Testo completoAbstract (sommario):
A laser-driven flyer impact system was constructed, characterized, and validated for performing uniaxial-strain experiments to investigate the shock equation-of-state (EOS) and processes leading to reaction initiation in thin, fully-dense Ni-Al nanolayered foils. Additionally, various fully-dense Ni-Al mixtures with highly heterogeneous microstructures and widely varying length scales were investigated to understand influence of meso-scale features on the shock compression and reaction response. Ni-Al composites are a class of reactive materials also called Structural Energetic Materials (SEMs), which aim to combine stiffness and strength with the ability to release large amounts of energy through highly exothermic reactions when the constituents are intimately mixed during shock loading. While porous reactive materials have been studied extensively, the processes leading to reaction initiation in fully-dense mixtures consisting of phases with disparate mechanical properties is more ambiguous. A table-top, small-scale laser system was developed for studying shock-induced effects in extremely thin reactive materials. Laser accelerated thin foil impact experiments utilizing time-resolved interferometry allowed for measuring the Hugoniot of the nanolayered Ni-Al foil over a range of particle velocities/pressures. Separate recovery experiments were performed by shock-loading Ni-Al foils slightly below the reaction initiation threshold and performing post-mortem TEM/STEM analysis to identify the constituent mixing processes leading to reaction. Direct-shock experiments were performed on the different fully-dense Ni-Al mixtures and hydrodynamic simulations using real microstructures allowed direct correlations with the experiment results, which yielded an improved understanding of the effect of phase arrangement on the shock propagation and reaction initiation response. The EOS experiments performed at particle velocities > 200 m/s showed a deviation from the predicted inert trend and recovered targets showed complete reaction to the B2-NiAl intermetallic phase. The measured deviation from inert behavior and state of recovered material suggests the occurrence of a shock-induced chemical reaction. The shocked (but unreacted) Ni-Al materials contained distinct constituent mixing features (layer jets and intermixed zones), where significant elemental penetration occurred and are likely sources of reaction initiation. The observed results provide the first clear evidence of shock-induced reactions in fully-dense nanolayered Ni-Al foils.
24
Ångström, Jonas. "Hydrogen absorption/desorption properties of the Sc(AlxNi1-x)2 system". Thesis, Uppsala universitet, Oorganisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159372.
Testo completoAbstract (sommario):
Sc(AlxNi1-x)2 is a pseudobinary C14 Laves phase and a potential interstitial hydrogen storage material or anode in a Ni-MH battery. A previous study showed that Sc1Al1Ni1 can store hydrogen reversibly; both interstitially and trough decomposition into ScH2 and AlNi. It is also known that the exact composition is very important for the hydrogen storage properties of pseudobinary Laves phases. This thesis work is aimed at synthesising Sc(AlxNi1-x)2 and study the effect of the Ni/Al ratio on the hydrogen absorption/desorption process as well as the interstitial storage capacity. Compositions with high nickel content had the highest capacity (at least 0.67wt% for ScAl0.66Ni1.34) and ones with high aluminium content had the lowest total storage capacity (0wt% for ScAl1.28Ni0.62). The former composition was also shown to absorb and desorb hydrogen during multiple cycles. Desorption of interstitial hydrogen from ScAl0.66Ni1.34 requires 4.6kJ/mol in activation energy.
25
Smith, Jarrod Lee. "Ductile Fracture Behavior of a Nickel-Based Superalloy and Thermally-Induced Strain Behavior of an Aluminum Alloy". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428427838.
Testo completo
26
Wu, Kaisheng. "Computer simulation of interdiffusion microstructures in multi-component and multiphase systems". Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5num=osu1064257423.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 155 p. : ill. (some col.). Advisor: Yunzhi Wang, Department of Materials Science and Engineering. Includes bibliographical references (p. 151-155).
27
Muzikant, Dušan. "Výroba optických zrcadel pro vysokofrekvenční antény". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229748.
Testo completoAbstract (sommario):
This thesis deals with problems with manufacturing of high frequency elliptic and hyperbolic optic mirrors, which makes one of the most important functional parts of parabolic satellites made for biggest and highest placed international astronomical radio-telescope in the world - ALMA, which is built on Chajnantor plateau in Chille in South America. Individual chapters are designed in the flow of technological process of manufacturing, containing theoretical and practical analysis of the problems. Content of the thesis leads especially to description and clarification of individual causes of problems during manufacturing.
28
Susan, Donald F. "Diffusion and high temperature oxidation of nickel-aluminum based composite coatings /". Diss., 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9955175.
Testo completo
29
Huang, Zhifan. "Environmentally enhanced crack growth in nickel-based superalloys /". Diss., 2002. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3073976.
Testo completo
30
Kartono, Rahmat Materials Science & Engineering Faculty of Science UNSW. "Effects of platinum, iridium, and hafnium to nickel-aluminium alloys under cyclic oxidation conditions". 2007. http://handle.unsw.edu.au/1959.4/40553.
Testo completoAbstract (sommario):
A thermally grown oxide (TGO) such as the alumina scale formed on a bondcoat enhances the oxidation and corrosion resistance of thermal barrier coating (TBC)- bondcoat-superalloy substrate systems. As the external alumina scale lies between the thermal barrier coating and bondcoat, its first spallation and subsequent TBC delamination become critical. Once the external alumina scale spalls, it will spall together with the TBC, leaving the system with no temperature barrier protection. Operational factors such as thermal cycling conditions, water vapour in the oxidation atmosphere, and alloying elements comprising the bondcoat system affect alumina scale adherence. Another problem that arises for the majority of bondcoat systems, β (Ni,Pt)Al and MCrAlY (M=Metal), are rich in aluminium. This causes aluminium to diffuse into the substrate, enriching it with aluminium during service, transforming phases in the substrate alloying system. The purpose of this study was to develop bondcoat materials that promote formation of a strongly adherent TGO, but have an aluminium content near the substrate composition. Cyclic oxidation experiments were performed with Ni-Al, Ni-Pt-Al, and Ni-Pt-Al-Ir alloys in dry air and air-12%H2O. Thermal cycles of 1 hr at 1200OC and 10 minutes at 80OC were carried out in flowing gases at a total pressure of 1 atm. Experiments in N2- 12%H2O were performed only on Ni-Al binary alloys. Binary Ni-Al cast alloys were tested for fundamental study purposes, while Ni-Pt-Al and Ni-Pt-Al-Ir cast alloys were intended to be models for aluminide coatings, with attention focused on γ+γ' -Ni-(20 to 23)Al. Comparisons were made with β-Ni-50Al, as it forms an external alumina scale and was found to have the smallest weight loss rate during testing of binary alloys. Assessments of Pt and Pt-Ir additions, with and without hafnium, to the γ+γ' binary alloy were made. Compared to binary alloys, platinum was found to reduce the total weight loss caused by scale spallation. Experiments in air-12%H2O led to more rapid weight loss than in dry air. This was due to enhanced spallation. However, the degradation rate was slower than in platinum-free alloys exposed to the same atmosphere. Partial replacement of platinum with iridium was found to improve alloy scale adherence during exposure in both dry and wet air. Addition of 1wt% hafnium was found to reduce oxide thickness and increase the oxide adherence simultaneously. The hafnium addition was essential in order to reduce spallation rate in wet air. Water vapour in the presence of oxygen generally increased the spallation rate. It weakened the oxide metal interface, causing subsequent spallation to be increased, but only if the gas had access to the alloy-scale interface. Water vapour did not affect the spallation rate of the strongly adherent oxide grown on Ni-22Al-30Pt+1wt%Hf and Ni- 20Al-15Pt-10Ir+1wt%Hf.
31
"corrosion of Ni-Al intermetallics =: 鎳鋁金屬間化合物的腐蝕". 1998. http://library.cuhk.edu.hk/record=b5896289.
Testo completoAbstract (sommario):
by Ka-Man Mak.Thesis (M.Phil.)--Chinese University of Hong Kong, 1998.
Includes bibliographical references.
Text in English; abstract also in Chinese.
by Ka-Man Mak.
Acknowledgement --- p.i
Abstract --- p.ii
List of tables --- p.v
List of figures --- p.vi
Table of contents --- p.xi
Chapter Chapter One --- Introduction --- p.1-1
Chapter 1.1 --- History of intermetallics --- p.1-1
Chapter 1.2 --- Properties of intermetallic compounds --- p.1-5
Chapter 1.2.1 --- Magnetic properties --- p.1-5
Chapter 1.2.2 --- Chemical properties --- p.1-6
Chapter 1.2.3 --- Semiconducting properties --- p.1-7
Chapter 1.2.4 --- Superconducting properties --- p.1-7
Chapter 1.2.5 --- Hydrogen storage --- p.1-8
References --- p.1-9
Chapter Chapter Two --- Background --- p.2-1
Chapter 2.1 --- Some Behaviours of Intermetallics
Chapter 2.1.1 --- Intergranular and cleavage fracture --- p.2-1
Chapter 2.1.2 --- Corrosion --- p.2-3
Chapter 2.1.3 --- Oxidation in high-temperature intermetallics --- p.2-5
Chapter 2.1.4 --- Hot corrosion --- p.2-8
Chapter 2.2 --- Nickel aluminides --- p.2-9
Chapter 2.2.1 --- Ni3Al --- p.2-10
Chapter 2.2.2 --- NiAl --- p.2-12
References --- p.2-14
Chapter Chapter Three --- Oxidation --- p.3-1
Chapter 3.1 --- Introduction --- p.3-1
Chapter 3.2 --- Specimens preparation --- p.3-1
Chapter 3.3 --- Experiment process --- p.3-5
Chapter 3.3.1 --- Instrumentation --- p.3-5
Chapter 3.3.2 --- Choosing of experimental temperature --- p.3-9
Chapter 3.3.3 --- Methodology --- p.3-9
Chapter 3.4 --- Results and Discussions --- p.3-10
Chapter 3.4.1 --- Dependence of time --- p.3-10
Chapter 3.4.2 --- Dependence of temperature --- p.3-14
Chapter 3.4.3 --- Dependence of composition --- p.3-15
Chapter 3.4.4 --- Activation energy of oxidation --- p.3-15
Chapter 3.4.5 --- Oxidation morphology and mechanism --- p.3-16
Chapter 3.5 --- Conclusions --- p.3-20
References --- p.3-21
Chapter Chapter Four --- Hot corrosion --- p.4-1
Chapter 4.1 --- Introduction --- p.4-1
Chapter 4.2 --- Specimens preparation --- p.4-1
Chapter 4.3 --- Experiment process --- p.4-3
Chapter 4.3.1 --- Instrumentation --- p.4-3
Chapter 4.3.2 --- Choosing of experimental environment and temperature --- p.4-5
Chapter 4.3.3 --- Methodology --- p.4-6
Chapter 4.3.3.1 --- Experiment --- p.4-6
Chapter 4.3.3.2 --- Experimental setup --- p.4-8
Chapter 4.4 --- Results and discussions --- p.4-9
Chapter 4.4.1 --- Dependence of time --- p.4-9
Chapter 4.4.2 --- Dependence of temperature --- p.4-10
Chapter 4.4.3 --- Comparison between hot corrosion with oxidation --- p.4-11
Chapter 4.4.4 --- Dependence of composition --- p.4-12
Chapter 4.4.4.1 --- Comparison between S1 and S2 --- p.4-12
Chapter 4.4.4.2 --- Comparison between S3- S7 --- p.4-12
Chapter 4.4.5 --- Results from XRPDS --- p.4-13
Chapter 4.4.6 --- Study of microstructure --- p.4-13
Chapter 4.4.6.1 --- Dependence on time --- p.4-14
Chapter 4.4.6.2 --- Dependence on temperature --- p.4-14
Chapter 4.4.6.3 --- Dependence on composition --- p.4-14
Chapter 4.5 --- Corrosion mechanism --- p.4-15
Chapter 4.5.1 --- Chemical reactions --- p.4-15
Chapter 4.5.2 --- Corrosion process --- p.4-16
Chapter 4.5.2.1 --- Temperature effect --- p.4-16
Chapter 4.5.2.2 --- Composition dependence --- p.4-17
Chapter 4.6 --- Conclusions --- p.4-18
References --- p.4-19
Chapter Chapter Five --- Conclusionsand suggestions for further studies --- p.5-1
Chapter 5.1 --- Oxidation --- p.5-1
Chapter 5.2 --- Hot corrosion --- p.5-2
Chapter 5.3 --- Further development --- p.5-3
32
Kanlayasiri, Kannachai. "Development of nickel aluminide (NiAl) microchannel array devices for high-temperature applications". Thesis, 2003. http://hdl.handle.net/1957/31482.
Testo completoAbstract (sommario):
The miniaturization of Microtechnology-based Energy, Chemical and
Biological Systems (MECS) is made possible by the use of high aspect ratio
microchannel arrays to increase the surface-area-to-volume ratio of the flow
conduits within the devices, resulting in an improvement in the heat and mass
transfer performance of the devices. However, advantages of the MECS concept
cannot be applied to high-temperature applications (above 650��C) due to lack of
high-temperature MECS devices; therefore, the development of high-temperature
MECS devices is necessary to overcome this bottleneck. This dissertation involves
the development of high-temperature MECS devices from a high-temperature
material, nickel aluminide (NiAl). NiAl foil was synthesized from elemental nickel
(Ni) and aluminum (Al) foils through a two step process--tack bonding and
reactive diffusion. The elemental foils were tack bonded at 500��C, 3.9 MPa for
15 minutes. The reactive diffusion process was then performed through a heat
treatment at 1000��C for a period of time corresponding to the thickness of the
composite foil. The synthesized NiAl foil showed an atomic ratio of Al to Ni up to
0.96. The foil also showed a decent flatness and surface roughness. This
dissertation proposes a reactive diffusion bonding as a joining technique of nickel
aluminides. An investigation of bonding parameter effects on the warpage of
nickel aluminide fins in the reactive diffusion bonding process was performed.
Results showed that bonding time and temperature had significant effects on
warpage of the fin. The fin warpage increased with the increase of bonding time
and bonding temperature. Results also suggested that the bonding pressure had an
effect on the fin warpage. However, chemical compositions of the fin were not
significant to the warpage. This research also proposes a new fabrication procedure
for producing NiAl MECS devices. NiAl foils were used as the starting material,
and the reactive diffusion bonding technique was employed as the joining
technique. The research outcome indicated the viability of the proposed method in
fabricating NiAl MECS devices. This method achieved leak-tight devices with a
reasonable fin flatness.Graduation date: 2003
33
Vierke, Jens [Verfasser]. "Processing and consolidation of amorphous and nanocrystalline Aluminum-Nickel-Lanthanum alloys / vorgelegt von Jens Vierke". 2007. http://d-nb.info/988773716/34.
Testo completo
34
Pei-ChiungLin e 林姵瓊. "Corrosion Characteristics of Iron, Copper, Nickel, Titanium and the Alloys in Aluminum Chloride – 1-ethyl-3-methylimidazolium Chloride Ionic Liquid". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/01024002443586316673.
Testo completo
35
Moreau, Eric D. "EFFECTS OF IRON AND NICKEL ON THE PROCESSING AND PERFORMANCE OF AN EMERGING ALUMINUM-COPPER-MAGNESIUM POWDER METALLURGY ALLOY". 2012. http://hdl.handle.net/10222/15049.
Testo completoAbstract (sommario):
Aluminum (Al) powder metallurgy (PM) provides a cost effective and environmentally
friendly means of creating lightweight, high performance, near net shape components,
relative to conventional casting/die casting technology. Unfortunately, the current lack of
commercially available Al alloy powder blends has hindered development in this field as
a result of the limited scope of mechanical properties available; especially under elevated
temperature conditions common to many automotive applications. As such, the objective
of this research was to attempt to improve the versatility of current Al PM technology
through the incorporation of Fe and Ni transition metal additions into an emerging Al-
4.4Cu-1.5Mg-0.2Sn alloy, as this technique is known to enhance the elevated temperature
stability of wrought/cast Al alloys through the formation of stable, Fe/Ni aluminide
dispersoids.
Initial experimentation consisted of evaluating the feasibility of incorporating Fe and Ni
both elementally and pre-alloyed, through a series of tests related to their PM processing
behaviour (compressibility, sintering response) and sintered product performance
(ambient tensile properties). Results confirmed that pre-alloying of the base Al powder
was the most effective means of incorporating Fe and Ni as all such specimens achieved
properties similar or slightly superior to the unmodified alloy. Of the pre-alloyed systems
considered, that containing 1%Fe+1%Ni displayed the most desirable results in terms of
mechanical performance and microstructural homogeneity of the Fe/Ni dispersoid phases
present in the sintered product.
Bars of the baseline system and that modified with pre-alloyed additions of 1Fe/1Ni were
then sintered industrially to gain a preliminary sense of commercial viability and obtain
additional specimens for elevated temperature exposure tests. Results confirmed that the
sintering response, tensile properties and microstructures were essentially identical in
both alloys whether they were sintered in a controlled laboratory setting or an industrial
production environment. Furthermore, DSC data indicated that S (Al2CuMg)-type phases
were the dominant precipitates formed during heat treatment. The effects of elevated
temperature exposure were assessed in the final stage of research. Both alloys were
found to exhibit comparable behaviour when exposed to the lowest (120°C) and highest
(280°C) temperatures considered. Here, the alloys showed no obvious degradation at
120°C. Conversely, exposure at 280°C prompted a steady decline in yield strength for
both alloys with significant precipitate coarsening noted as well. Despite these
similarities, differences emerged during isochronal tests at intermediate temperatures.
Here, DSC data indicated that the precipitates present in the pre-alloyed material were
stable at temperatures up to 160°C while those in the unmodified alloy had begun to
overage under the same exposure conditions. These differences were accompanied by
increased stability in tensile yield strength for the pre-alloyed material. In all, this study
has indicated that the use of Al powder pre-alloyed with Fe/Ni additions is feasible for
press-and-sinter PM technology and that the sintered product exhibits improved elevated
temperature stability under certain conditions.
36
Eluri, Ravindranadh T. "Nanoparticle-assisted diffusion brazing of metal microchannel arrays : nanoparticle synthesis, deposition, and characterization". Thesis, 2012. http://hdl.handle.net/1957/28651.
Testo completoAbstract (sommario):
Microchannel process technology (MPT) offers several advantages to the field of nanomanufacturing: 1) improved process control over very short time intervals owing to shorter diffusional distances; and 2) reduced reactor size due to high surface area to volume ratios and enhanced heat and mass transfer. The objective of this thesis was to consider how nanomaterials, produced in part using MPT, could be used to solve problems associated with the fabrication of MPT devices. Specifically, many MPT devices are produced using transient liquid-phase brazing involving an electroplated interlayer consisting of a brazing alloy designed for melting temperature suppression. Unfortunately, these alloys can form brittle secondary phases which significantly reduce bond strength. In contrast, prior efforts have shown that it is possible to leverage the size-dependent properties of nanomaterials to suppress brazing temperatures. In this prior work, thin films of off-the-shelf elemental nanoparticles were used as interlayers yielding joints with improved mechanical properties.
In the present investigation, efforts have been made to characterize the synthesis and deposition of various elemental nanoparticle suspensions for use in the transient liquid-phase brazing of aluminum and stainless steel. Advances were used to demonstrate the nanoparticle-assisted diffusion brazing of a microchannel array. In the first section, a silver nanoparticle (AgNP) interlayer was produced for the diffusion brazing of heat exchanger aluminum. Efforts are made to examine the effect of braze filler particle size (~5 nm and ~50 nm) and processing parameters (heating rate: 5ºC/min and 25ºC/min; brazing temperature: 550ºC and 570ºC) on thin coupons of diffusion-brazed 3003 Al. A tensile strength of 69.7 MPa was achieved for a sample brazed at 570°C for 30 min under 1 MPa with an interlayer thickness of approximately 7 μm. Further suppression of the brazing temperature to 500ºC was achieved by sputtering a 1 µm thick layer of Cu before depositing a 5 nm thick film of AgNPs resulting in a lap shear strength of 45.3±0.2 MPa. In the middle section of this thesis, several techniques are investigated for the synthesis of sub 10 nm diameter nickel nanoparticles (NiNPs) to be used in the diffusion brazing of 316L stainless steel. The average NiNP size was varied from 9.2 nm to 3.9 nm based on the synthesis technique, solvent and reducing agent used. Conventional wet-chemical synthesis using NiCl₂.6H₂O in ethylene glycol (solvent) and N₂H₄.H₂O (reducing agent) resulted in the formation of 5.4 ± 0.9 nm NiNPs. Continuous flow synthesis using a microchannel T-mixer (barrel diameter of 521µm) and a 10 second residence time of reactants in a bath temperature of 130ºC resulted in a particle size of with 5.3 ± 1 nm. To make the synthesis safer and less energy intense, microwave heating was used along with less toxic Ni(CH₃CO₂)₂·4H₂O (nickel salt), propylene glycol (solvent) and NaPH₂O₂ (reducing agent) yielding 3.9 ± 0.8 nm diameter NiNPs. For the final section, nickel nanoparticles were synthesized using NiCl₂.6H₂O (nickel salt), de-ionized water (solvent), NaBH₄ (co-reducing agent), N₂H₄.H₂O (reducing agent) and polyvinylpyrolidone (capping agent) yielding 4.2 ± 0.6 nm NiNP. Several deposition techniques were investigated for controlling film thickness and uniformity in the diffusion brazing of 316L stainless steel (SS). Using in-house prepared NiNP and automated dispensing, a hermetic joint up to 70 psi (tested pressure) was obtained in 316L SS substrates under brazing conditions of 800ºC, 2 MPa and 30 min. Throughout the course of this thesis, techniques used for characterizing nanoparticles, films and joints included FT-IR, XRD, SEM, TEM, HRTEM, EDS, EPMA, DSC, mass spectrometry, and lap-shear testing.Graduation date: 2012
37
Hsu, Ssu-Hsien, e 許思賢. "Electroless nickel plating on wear resistance of 7075 aluminum alloy by micro-arc oxidation". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/31267547552191411479.
Testo completoAbstract (sommario):
碩士元智大學
機械工程學系
99
In this study, micro-arc oxidation of 7075 aluminum alloy was used as substrate to deposit ENi plating with the different time by electroless nickel technology. And then characteristics of electroless nickel plating, such as structure, roughness and hardness behaviors of the plated specimens were analyzed and compared. Mechanical properties and wear resistance were analyzed in order to understand the effect of ENi plating for the specimens. The plating thickness is increased with increasing hardness, , and wear resistance also increased because hardness. Microstructures of surface can be observed that plating time increased with increasing the surface of particles. The surface roughness should rise in theory, but the results were not. Observed the section of microstructure found plating with the micro-arc oxidized layer formation. ENi plating surface relief caused by surface roughness does not increase with increasing thickness of the coating.
38
Potnis, Prashant R. "Study Of Fracture Properties Of NiAl Bond Coats On Nickel Superalloy By Three Point Bending Of Microbeams". Thesis, 2007. http://hdl.handle.net/2005/498.
Testo completoAbstract (sommario):
The continuing quest for higher performance levels of modern gas turbine engines has been accompanied by the demand for higher engine operating temperatures. The use of Thermal Barrier Coatings (TBCs) enabled gas turbines to operate at higher temperatures by protecting the blade material (nickel superalloy) while operating in extreme environments. The TBC system typically consists of a bond coat for protection of the nickel–based superalloy against oxidation followed by a top coat consisting of a thermally insulating zirconia-yttria.
In addition to the complex gradation in phases, the coatings are subjected to continuous oxidation with service exposure, mechanical loading on rotating parts, fatigue, thermal mis-match and temperature gradients. Hence, the study of failure mechanisms of TBCs become important in deciding operational reliability and service life of the coating. As there are many systems in which the operating temperatures are not high enough to warrant the use of the top coat (ceramic layer), the study of failure mechanisms in superalloys coated with only the bond coat continue to be of great interest.
The present work concentrates on the fracture behavior of NiAl bond coats on nickel superalloy and seeks to evaluate the fracture toughness of the coating through the use of micro-machined samples. A review of the relevant literature indicated that while a considerable body of work exists on bulk tests of failure (spalling, splitting, etc.), not much has been reported in the open literature on the evaluation of basic quantities such as the toughness of the coating itself.
The present thesis seeks to establish a protocol for the evaluation of toughness and crack propagation mechanisms in coatings through a combination of micro-sample testing that allows fracture to be correlated with location in the film and the use of an analytical model to quantitatively evaluate stress intensity factors in a bi-material system.
A system of NiAl coating produced by pack aluminizing is studied for the fracture properties of the coating. Specimen geometries are optimized to enable micro-cracks to be machined and propagated in a low load testing system, such as a depth sensing indenter, so that crack lengths (and position relative to the interface) can be correlated with load. To enable linear elastic theory to be used, dimensions are determined that allow fracture before general yielding. A three point bending test using miniaturized micro-beam specimens of ~ 4 X 0.3 X 0.3 mm is found to be suitable for the above purpose. The technique is a challenging one that requires focused ion beam machining (FIB) along with careful handling and alignment of small samples.
The coatings are characterized for their microstructure by electron microscopy to identify compositional variation across the thickness and to determine the thickness of the coating and inter diffusion zone (IDZ). The crack advancement is monitored with increments of loading and the stress intensity factor is evaluated using a program written in “MAPLE” for an edge crack subjected to bending in a bilayered material. Surprisingly, fracture in this system is found to be stable owing to a gradual increase in toughness from the coating surface to the interface. Such an increase from less than 2 to more than 9 MPa m0.5 may be due to the increasing Ni/Al ratio across the thickness of the bond coat. Crack branching is observed as the crack approaches the IDZ and the reasons for such behaviour are not fully understood.
This work establishes the viability of this technique to determine fracture properties in highly graded coated systems and may be readily extended to more complex coating architectures and other forms of loading such as cyclic, mixed mode, etc.
39
Chen, Ming-Chang, e 陳明昌. "Study the difference of the Pre-Treatment and Past-Treatment of Aluminum Alloy in the Electroless Nickel Plating Process and Coating Defects". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/50975385856701688743.
Testo completoAbstract (sommario):
碩士國立高雄應用科技大學
機械與精密工程研究所
96
The study is divided into pre-treatment and past-treatment of aluminum alloy in the electroless nickel plating process: The first-part study, carry on the discussion with different surface roughness characteristic of aluminum alloy in the same specimen(grind and polishing surface) and reflect on in the electroless nickel plating procedure. Find out what was the best process and time in electroless nickel plating influence and secondary Zincate of Aluminum alloy. The second-part study, how to de-gas of the hydrogen that will be produced after the electroless nickel plating influence from the surface of aluminum alloy. By the results and discussions after many testings of electroless nickel plating, comprehensive the following: 1. The electroless nickel plating was chemical reaction, so it’s very much important about the clean and density of the chemical nickel liquid. All of water for cleaning and allocating was the de-ionized water. After the pre-treatment for the aluminum alloy(using acetone ultrasound shock and washed ultrasound), keep it on 10wt% & 15℃ NaOH cleaning for 8 minutes was the best pre-treatment etching acid process. 2. The Secondary Zincate of Aluminum Alloy, the best reaction time and process was: The first road soaking zincate 40 seconds, 50wt％ HNO3 for zinc stripping 10 seconds, the second road soaking zincate 30 seconds. 3. According the tests, I found that the corrosion-resistant surface roughness Ra value was low or the surface was smooth, the combination of insufficient coating, will significantly affect corrosion resistance. The appropriate surface roughness can increase the corrosion resistance. 4. After the electroless nickel plating influence, how to de-gas of the hydrogen from the aluminum alloy: (1) Used air pump: Let the air into the chemical nickel liquid and de- hydrogen from the aluminum alloy. But this way, it caused the appearance defect, Aluminum alloy didn’t be plated by the nickel layer all over the surface. (2) Used water pump in the chemical nickel liquid: The water pump could form “chemical nickel liquid” column. The hydrogen would be de-gas with the “chemical nickel liquid”column. The appearance of the electroless nickel films almost was perfect without defect. Although corrosion resistance test for 24-hour by acid liquid also not be perfect, but the corrosion situation is better than before.