Two types of intrinsic defect, i.e., vacancy and self-interstitial atom, were formed in metals during irradiation with energetic particles. The evolution of defect population leads to significant changes in microstructure and caused a number of radiation-induced property changes. Some phenomena, such as radiation growth of anisotropic materials,

were due to anisotropy in the atomic mass transport by point defects. Detailed information on atomic-scale mechanisms is, therefore, necessary to understand such phenomena. The results were presented here of a computer simulation study of mass transport via point defects in α-Zr. The matrix of self-diffusion coefficients and activation energies for vacancy and self-interstitial atom defects were obtained, and different methods of treatment of diffusion were tested. Molecular dynamics showed that vacancy diffusion was approximately isotropic at 1050 to 1650K, although some preference for basal-plane diffusion was observed at the lower end of the range. The mechanism of interstitial diffusion changed from 1-dimensional below 300K, to 2-dimensional in the basal plane and then 3-dimensional at higher temperatures.

Anisotropy of Point Defect Diffusion in Alpha-Zirconium. Y.N.Osetsky, D.J.Bacon, N.de Diego: Metallurgical and Materials Transactions A, 2002, 33[3A], 777-82