Analysis of the anisotropy of point defect diffusion in hcp Zr

作者：Samolyuk G D^*; Barashev A V; Golubov S I; Osetsky Y N; Stoller R E

来源：Acta Materialia, 2014, 78: 173-180.

DOI：10.1016/j.actamat.2014.06.024

• Zirconium
• Diffusion
• Density functional theory
• Kinetic Monte Carlo
• Vacancies and interstitials

A combination of density functional theory (DFT), kinetic Monte Carlo and mean-field rate theory is applied to analyze point defect migration and its effect on the observed growth of hexagonal close-packed (hcp) Zr under 1 MeV electron irradiation. DFT is used to study stability of various configurations of vacancies and self-interstitial atoms (SIAs) and migration barriers. The data are used in kinetic Monte Carlo modeling of defect diffusion at different temperatures. It is found that both defects exhibit anisotropic diffusion, predominantly parallel to the basal planes. The ratio of diffusion coefficients parallel and perpendicular to the basal planes is found to be higher for vacancies as compared to SIAs at temperatures below similar to 600 K. This raises doubts that the observed radiation growth in Zr irradiated with 1 MeV electrons, namely positive strains in prismatic and negative strains in basal directions, and void alignment along basal planes, can be accounted for by the anisotropy of point defect diffusion, which predicts opposite strain signs. It is speculated that formation of small SIA clusters with higher diffusion anisotropy may be responsible for the experimental observations. Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

• 出版日期2014-10-1