Anisotropic diffusion of point defects in metals under a biaxial stress field simulation and theory

Abstract

We study the diffusion anisotropy (DA) of point defects in fcc and bcc metals in the presence of an applied biaxial stress. The DA depends sensitively on both the crystalline structure and the crystallographic direction in which the stress is applied. For example, interstitials in fcc metals diffuse faster in the plane of the compressive stress than normal to it when the stress is applied to the (001) plane, but they diffuse slower in-plane than out-of-plane when the stress is applied in the (111) plane. In contrast, an applied biaxial stress in the (001) plane of a bcc metal does not cause DA. These results can be explained by considering the interaction of the defects at their saddle point configurations with the external field, together with the constraints imposed by the crystal structure on the defect jump directions. Our calculations show that the DA can be large and lead to surprising results in a number of practical situations.

Calculation of strain effects on vacancy-mediated diffusion of impurities in fcc structures: General approach and application toNi1−xSix

“…Defects such as dislocations or interfaces act as sinks for point defects but also generate a strain field, which alters diffusion properties [10][11][12][13] . By breaking the symmetry of the crystal structure, the strain field induces anisotropy of the diffusion properties 10,11,13 The Onsager matrix-which relates chemical potential gradients to atomic fluxes-is then a second-rank tensor.…”

“…By breaking the symmetry of the crystal structure, the strain field induces anisotropy of the diffusion properties 10,11,13 The Onsager matrix-which relates chemical potential gradients to atomic fluxes-is then a second-rank tensor. The Onsager matrix of diverse cubic structures has been computed [14][15][16][17][18][19][20][21][22] .…”

KineCluE: A kinetic cluster expansion code to compute transport coefficients beyond the dilute limit

“…KineCluE allows for an essentially seamless application of the SCMF cluster-expansion method to strained systems, thus widely improving the state-ofthe-art models for computing fully strain-dependent transport matrices. Strain-dependent diffusion coefficients have been measured by molecular dynamics [88] and by Monte Carlo simulations [89], but it has been shown that measuring the elasto-diffusion tensor with the latter method is tricky [90]. Previous analytical models allowing for such kind of calculations were based on:…”

Kinetic Monte Carlo investigation of tetragonal strain on Onsager matrices

“…Garnier et al [20] found that the strain field near an edge dislocation in Ni causes complex flow patterns for Si solutes and vacancies. Chan et al [21] performed atomic simulations in face-centered cubic (FCC) Pt and Cu to show that the anisotropic diffusion of vacancies and self-interstitials under strain strongly depends on the crystal structure and the crystallographic directions in which the strain is applied.…”