The configuration and energetics of the mono-vacancy and self-interstitial of hexagonal close-packed Zr, in both the ground state and saddle-point configurations, were computed atomistically using the conjugate gradient method, from which the diffusion anisotropy difference between the 2 types of defects was obtained. Based upon this information, the growth rates of interstitial loops of various Burgers vectors in a Zr foil irradiated in a high-voltage electron microscope and the stress-free in-reactor deformation rates in hexagonal close-packed Zr were calculated directly. In both cases, the experimental observations were shown to be well accounted for. The significance of the diffusion anisotropy difference effect was thereby directly confirmed.

Atomistic Calculation of Point-Defect Diffusion Anisotropy and Irradiation Growth in α-Zirconium. C.H.Woo, X.Liu: Philosophical Magazine, 2007, 87[16], 2355-69