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Showing 1 to 20 of 33 for “"grain boundary diffusion"”.
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Simulation of Bulk and Grain Boundary Diffusion in B2 NiAl
Molecular dynamics simulations of the diffusion process in ordered B2 compounds at high temperature were performed using an embedded atom interatomic potential developed to fit NiAl properties. Diffusion in the bulk occurs through a variety of cyclic mechanisms that accomplish the motion of the …
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Toward the measurement of reliable grain-boundary diffusion coefficients in oxides
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.
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Secondary-ion mass spectrometric analysis of oxygen-grain boundary diffusion in magnesium-oxide bicrystals
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.
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The effects of dopants and complexions on grain boundary diffusion and fracture toughness in α-Al2O3
Grain boundaries often play a dominant role in determining material properties and processing, which originates from their distinct local structures, chemistry, and properties. Understanding and controlling grain boundary structure-property relationships has been an ongoing challenge that is …
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Grain boundary self-diffusion in sodium chloride
"The diffusion of ²²sodium and ³⁶chlorine along tilt and twist grain boundaries in pure and calcium chloride doped sodium chloride bicrystals was investigated. No enhanced diffusion of ²²sodium along the grain boundaries was observed. Between 400°C and 500°C the chlorine grain boundary diffusion …
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Densification and Mechanical Properties of Nanocrystalline FeAl
… is attributed to a deformation mechanism of grain boundary sliding. The discrepancy between the stress exponent in sinterforging and impression creep tests is attributed to the lower stresses employed in the impression creep experiments, suggesting different mechanisms are presumably in …
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Solid state diffusion in Pd₂Si
… studied to try and establish the mechanism(s) of diffusion by which the growth of Pd₂Si proceeds under thermal annealing. Using a deposited Ti marker, the dominant moving species during Pd₂Si formation in the temperature range 250-400°C has been determined to be silicon. Palladium transport …
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A Numerical Study of Intergranular and Oxidation-Driven Fracture in an Elastic-Viscoplastic Material
… driven by the infiltration and embrittlement of grain boundaries by oxygen. A novel space-time finite element model is developed to study this mechanism. The numerical model provides the basis for generic investigations of the kinetics of quasi-static crack growth along a brittle interface (such …
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Modification of space charge transport in nanocrystalline cerium oxide by heterogeneous doping
… was developed in which thin NiO and Gd203 diffusion sources were deposited on the ceria surface and annealed in the temperature range of 7008000C in order to diffuse the cations into the ceria layer exclusively along grain boundaries. Time-offlight secondary ion mass spectrometry (ToF-SIMS) …
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Synthesis, Consolidation, and Mechanical Testing of Nanophase Metals
… specimens are lower than activation energy for grain boundary diffusion in microcrystalline materials. A model is proposed to explain the higher creep rate. It assumes that the specimens produced from vapor condensed powders have a higher grain boundary energy due to a higher disorder in their …
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Ion assisted deposition of multicomponent thin films
… the mechanism of this reaction was dominated by grain boundary diffusion of the participating cations.
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Silicon and oxygen self-diffusion in forsterite and implications to upper-mantle rheology
(1) Silicon lattice diffusion coefficient in dry forsterite The high temperature creep of olivine is believed to be controlled by self-diffusion of olivine. However, the experimentally measured silicon diffusion coefficients (DSi) [Dohmen et al., 2002; Jaoul et al., 1981] were about 2-3 orders of …
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Gefügeeinfluß auf das Elektromigrationsverhalten von Kupferleitbahnen für höchstintegrierte Schaltungen
… is unknown. In this work the influence of the grain boundaries and their properties on the electromigration is examined at sputtered (PVD) and electroplated (ECD) Copper interconnects. For this investigation microstructure mappings produced by electron backscatter diffraction (EBSD) are …
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Effect of microstructural constituents on hydrogen diffusion in multiphase alloys
… strong link between microstructure and hydrogen diffusion and embrittlement in all metallic systems, the correlation between the two is poorly documented. It is, however, sorely needed as the current research shows that by quantifying the type and density of defects along with their associated …
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Modeling and simulation of creep rupture in high-temperature alloys
… growth, and coalescence of voids along grain boundaries. It is also well known that intergranular voids grow under the influence of several physical processes, including matter diffusion along the void surface, matter diffusion along the grain boundary, and bulk creep of the surrounding …
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DESIGN AND SYNTHESIS OF STAINLESS-STEEL NANOPARTICLES: OXIDATION BEHAVIOR AND MORPHOLOGICAL EVOLUTION
… shell thickness and shell-deposition routes, and diffusion data for Fe/Cr, Fe/Ni, and Fe/CrNi core/shell NP systems is provided. In chapter 3, I describe the synthesis of cube-shaped FexCr1-x alloy NPs, oxidation and the subsequent formation of internal voids. HRTEM images of oxidized alloy NPs …
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Modeling tin sulfide grain growth during post-processing
… further research is being done on the grain structure and how grain growth occurs under different annealing conditions. After thermal evaporation deposition, three different conditions were varied during annealing to affect grain growth: time, temperature, and annealing atmosphere. The …
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Tensile Stress and Thermal Growth Effects on Grain Boundary Motion in Nanocrystalline Nickel
… involve molecular dynamics (MD) simulations of grain boundary motion in nanocrystalline (nc) nickel. The first study is conducted to examine the effects of an applied tensile stress on the grain boundary motion in 5 nm3 nc-Ni specimens, half of which contain free surfaces, while the other half …
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Grain Boundary Solute Segregation in Vanadium
… fusion applications, where the presence of grain boundaries can improve mechanical properties and act as a sink for radiation- induced defects. Solutes with a thermodynamic preference to segregate to grain boundaries can stabilize them, making this a prime consideration for alloy design, but …
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Constrained sintering of gold circuit films on rigid substrates
… studies also showed no significant difference in grain size between the sintered freestanding and constrained gold films. Inplane tensile stresses generated during constrained-film sintering, was determined to have a maximum value of 460 KPa at the sintering temperature of 750°C. The negligible …
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