Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 60 for “"Grain Structure"”.
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Sub-Grain Structure of Machined Copper and Stainless Steel
Made available in DSpace on 2014-12-09T17:13:42Z (GMT). No. of bitstreams: 1 6808053.pdf: 5144570 bytes, checksum: acb3554fa6335e2b5b50f30135ed5070 (MD5) Previous issue date: 1967
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Relationships between grain structure and stress in thin Volmer-Weber metallic films
… the substrate surface impinge and coalesce into grains of a continuous film. During deposition of these polycrystalline films, the intrinsic stress for materials of sufficiently high mobility often evolves through three distinct stages, switching from compressive to tensile and back to …
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Semi-conductor Core Optical Fibers and Fabrication Dependence of the Grain Structure
… 4 fiber types, an experiment on controlling the grain length in the core and a simple model of the heat transfer during fabrication. Fibers were first made with a silicon core, followed by a phosphorous doped n-type silicon core, then a boron doped p-type silicon core, and a tellurium doped …
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Effect of grain structure and doping on the mechanical properties of polysilicon thin films for MEMS
… engineered by modification of the material microstructure. Such advances require detailed experimental studies and quantitative understanding of the convoluted effects of the processing methods on the ensuing mechanical properties. This dissertation investigated the role of grain size and doping …
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The effects of grain structure and Cu distribution on the relability of near-bamboo Al-Cu alloy interconnects
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1997.
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Development of a melting and directional solidification process for improving the grain structure and electronic properties of a silicon wafer
… to melt and directionally solidify fine-grained silicon wafers at accelerated feed rates for improved electronic properties. The proposed process encapsulates a fine grained silicon wafer which is then sandwiched between two substrates with a specialized release layer. This stack is then …
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Development of Niobium Boron grain retainer for aluminium silicon alloys
Aluminium castings with a large grain structure have poor mechanical properties which are primarily due to casting defects as opposed to fine grain structure. The grain refinement practice using chemical addition is well established for wrought alloys, however in the case of casting alloys, the …
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Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials
… systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy …
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Silicon cast wafer recrystallization for photovoltaic applications
… Subsequently, the electrical properties (through grain structure, dislocation density, and segregation of impurities) are optimized by zone recrystallization. The work outlined in this report documents the development of a custom, high- purity zone recrystallization furnace; an encapsulation …
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Microstructure evolution and interconnect realiability
… of predicting the effects of geometry, microstructure, and processing conditions on electromigration (EM) induced interconnect failure, normal grain growth in thin films was studied, analytic models were built for the grain structure statistics in 2D and 3D interconnects, and simulation …
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Low and Structure at Constant Temperature in a Superplastic Fe-Al-Mn-C Alloy.
Micrograin superplasticity is that property of some metals to elongate many times their original lengths during deformation at elevated temperatures. Micrograin superplasticity is exhibited during deformation at constant temperature by metals having a fine grain structure and is to be distinguished …
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Wire Direct Energy Deposition of Cobalt Iron Alloy
… showed single phase BCC with fine equiaxed structure and high density (>98.5%) with no pores or cracks. ASTM A773 sample rings were printed and showed that for decreasing input energy (by decreasing power or increasing feed speed) leads to a finer grain structure. The average diameter grain …
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Friction stir welding of high temperature alloys
… and correlation between processing, microstructure and mechanical properties. Tool performance study was carried out for Ti-6Al-4V alloy with refractory tools made of W-1.1%La₂O₃ and two different grades of WC-Co based materials. The results showed that tool degradation can be attributed …
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Mechanics and manufacturing of crosslinked cellulose nanocomposites
… (CNCs) are naturally derived and renewable nanostructures with exceptional mechanical and chemical properties. Consequently, CNCs provide a compelling platform to study the mechanical properties and manufacturing processes of nanocomposites, toward sustainable, high-performance structural …
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Spot Friction Welding of Ultra High-Strength Automotive Sheet Steel
… readings were taken in cross sectioned samples. Grain structure in a SFW is presented. Resistance spot welds were created in three steels. This study focuses on the strength of SFW joints as compared to traditional resistance spot welding (RSW) in welding like materials to one another. Cycle …
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Tensile Fracture Mechanisms of Ferritic/martensitic Structural Materials
… of tri-axial stress and severe distortion of grain structure in the necking region, it is a challenge to determine the true strain/stress curve, a critical input in finite element modeling (FEM) analysis. Previous scholars have developed several analytical methods to characterize true …
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Effects of thermomechanical processing on microstructure and hardness profiles in AA6061 plates
… (?), strain rate (?) and temperature (T) - on grain structure and hardness evolution in AA6061 plates were investigated by simulating the rolling process using plane strain compression (PSG). Particular emphasis was exerted on understanding the impact of the variables on the overall mean grain …
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Characterizing the tensile behavior of additively manufactured Ti-6Al-4V using multiscale digital image correlation
… characterizing the relationship between the microstructure and bulk mechanical properties of the AM Ti-6Al-4V specimens and understanding how unique microstructural features pertaining to AM metals, such as columnar grain morphology and nonequilibrium phase structures, influence the micro-scale …
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Investigating effects of interpass time during hot finish rolling on the evolution of texture in AA3104 Can Body Stock
… along the strip length leads to non-uniform microstructure and texture development, which impacts material properties. This study investigated the microstructure and texture evolution in AA3104 can body stock (CBS) during hot finish rolling by simulating multi-pass, high-temperature plane strain …
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Edge Fracture Prediction Of Dual Phase Steels With Consideration Of Microstructures
… computer modeling with the consideration of microstructure effect.</p> <p>In this dissertation, Hole Expansion (HE) test was used to investigate the mechanisms of edge fracture of two AHSS, Dual Phase DP780 and DP980. The HE test includes two processing steps: hole punching and hole expanding. The …
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