Papers by Keyword: Grain Boundary Dislocation

Abstract: The interaction of atom-atom collisions cascades with Ni-Al interphase boundary was studied by the method of molecular dynamics. It was shown that the interphase boundary partially absorbs the cascade energy. The degree of energy absorption of the cascade by the interphase boundary increases with the growth of the structural imperfection of the boundary and density of the misfit dislocations, and also with increase of distance between the boundary and the place of the cascade initiation.

Abstract: The paper is devoted to the research of diffusion mechanism in Ni3Al intermetallide over grain boundaries of tilt <111> and <100> by the method of molecular dynamics. It was found that grain boundary diffusion represented the combination of three main mechanisms: migration of atoms along the nuclei of grain boundary dislocations, cyclic mechanism near the nuclei and the formation of the chain of displaced atoms from one nucleus of dislocation to the nucleus of the other one. Diffusion mobility of Ni atoms was essentially bigger than the mobility of Al atoms. Grain boundary slipping and intergrain slipping were also observed during the deformation of the bicrystal.

Abstract: We present results of atomistic computer simulations of spontaneous and stress-induced grain boundary (GB) migration in copper. Several symmetrical tilt GBs have been studied using the embedded-atom method and molecular dynamics. The GBs are observed to spontaneously migrate in a random manner. This spontaneous GB motion is always accompanied by relative translations of the grains parallel to the GB plane. Furthermore, external shear stresses applied parallel to the GB and normal to the tilt axis induce GB migration. Strong coupling is observed between the normal GB velocity vn and the grain translation rate v||. The mechanism of GB motion is established to be local lattice rotation within the GB core that does not involve any GB diffusion or sliding. The coupling constant between vn and v|| predicted within a simple geometric model accurately matches the molecular dynamics observations.

Abstract: A computer simulation-based approach has been developed in order to reveal grain boundary defect structure of nanomaterials, which is described in terms of extrinsic grain boundary dislocations. On the basis of comparative analysis of numerically obtained results to experimental data, the defect structure parameters of nanostructured materials produced by severe plastic deformation have been evaluated.