The density and the character of dislocations and the size-distribution of grains or subgrains were determined by a new procedure of X-ray diffraction (XRD) profile analysis in copper specimens deformed by equal channel angular pressing (ECA) or cold rolling. The anisotropic strain broadening of diffraction profiles was accounted for by dislocation contrast factors. The screw or edge character ...

We present high resolution observations of microstructure and texture evolution during dynamic recrystallization (DRX) of ice polycrystals deformed in the laboratory at high temperature (≈0.98Tm). Ice possesses a significant viscoplastic anisotropy that induces strong strain heterogeneities, which result in an early occurrence of DRX mechanisms. It is therefore a model material to explore these...

End of range ~EOR! defects are the most commonly observed defects in ultrashallow junction devices. They nucleate at the amorphous-crystalline interface upon annealing after amorphization due to ion implantation. EOR defects range from small interstitial clusters of a few atoms to $311% defects and dislocation loops. They are extrinsic defects and evolve during annealing. Li and Jones @Appl. Ph...

SECOND ORDER PYRAMIDAL SLIP IN ZINC SINGLE CRYSTALS K. H. Adams,* R. C. Blish and T. Vreeland, Jr. W. M. Keck Laboratory of Engineering Materials California Institute of Technology Pasadena, California (U.S.A.) CALT-473-18 Measurements of strain, dislocation mobility and dislocation density have been made in 99.999% zinc single crystals stressed at room temperatur~ j_n comp.!:_ession along the ...

A dramatic reduction of the dislocation density in GaN was obtained by insertion of a single thin interlayer grown at an intermediate temperature (IT-IL) after the initial growth at high temperature. A description of the growth process is presented with characterization results aimed at understanding the mechanisms of reduction in dislocation density. A large percentage of the threading disloca...

The strain field of isolated screw and edge dislocation cores in aluminum are calculated using density-functional theory and a flexible boundary condition method. Nye tensor density contours and differential displacement fields are used to accurately bound Shockley partial separation distances. Our results of 5-7.5 A (screw) and 7.0-9.5 A (edge) eliminate uncertainties resulting from the wide r...

GaN layers grown by metal organic vapour phase epitaxy on sapphire were imaged by synchrotron radiation X-ray topography. The threading dislocations could not be resolved in the topographs due to their high density, but a smaller density of about 105 cm-2 misfit dislocations were seen in the interface between GaN and sapphire by using large-area backreflection topography. The misfit dislocation...

The concept of multiscale architectured materials is established using composition and grain size gradients. Composition-gradient nanostructured materials are produced from coarse grained interstitial free steels via carburization and high-pressure torsion. Quantitative analyses of the dislocation density using X-ray diffraction and microstructural studies clearly demonstrate the gradients of t...

Al7075 alloy reinforced with h-Boron Nitrate (BN) composites were processed by stir casting technique. The produced composite was subjected to microstructural studies using OLYMPUS -BX51M, tensile, hardness, density and wear tests. Tensile strength and hardness were found to increase by 12.8% and 20% respectively due to increased dislocation density with the addition of reinforcement. Microstru...

We report evidence for a significant increase of bulk dislocation density upon poling of polycrystalline BaTiO3. The synchrotron high-resolution x-ray-diffraction measurements yield a dislocation density on the order of 10/cm and an associated strain-energy increase of about 20 kJ/m. This implies that the application of an external poling field generates defects in the structure and increases t...