The structure and properties of planar interstitial and vacancy clusters, in α-Zr containing up to about 300 defects, were studied using atomic-scale computer modelling. Clusters of differing shape and habit-plane were simulated at zero temperature. Vacancy clusters were constructed as close-packed platelets of vacancies in (00•1), {11•0} and {1¯1•0} planes. Clusters of self-interstitial atoms were formed as planar arrays of <11•0> crowdions (the most stable configuration for the model potential used) on a {11•0} plane. The most favourable shape for both types on the {11•0} and {1¯1•0} prism planes was rectangular, and clusters relaxed to give perfect dislocation loops with a Burgers vector of 1/3<11•0>. Their stability was increased by dissociation of the sides on basal planes. Vacancy clusters on the (00•1) basal plane formed hexagonal loops which enclosed an extrinsic stacking fault with a Burgers vector of ½[00•1].

Structure and Properties of Vacancy and Interstitial Clusters in α-Zirconium. N.de Diego, Y.N.Osetsky, D.J.Bacon: Journal of Nuclear Materials, 2008, 374[1-2], 87-94