Identification and morphology of point defect clusters created in displacement cascades in α-zirconium

Abstract

Atomic scale computer simulation of high-energy displacement cascades in α-zirconium has been carried out for a wide range of primary knock-on atom energy (10–25keV) and temperature (100–600K). A large number of vacancy and self-interstitial atom (SIA) clusters of various shapes and sizes was generated in more than 240 cascades. In spite of the variety of cluster structures, they can be categorized into three distinct configurations for vacancy and SIA clusters. Internal atom arrangements for all point defect clusters have been established and the type of stacking faults that can be assigned to vacancy clusters identified. The explanation of different relaxation patterns of prismatic vacancy loops occupying either even or odd number of neighbouring close-packed planes is suggested. Transformation of the pyramid-like vacancy cluster with a basal-plane extrinsic fault into prismatic vacancy loop is considered.