Anisotropic distribution of dislocation loops in HVEM‐irradiated Zr

Abstract

Specimens of Zr have been electron-irradiated at temperatures of ∼715 K using a 1 MeV electron microscope. The damage structure has been analysed at room temperature, and the results show that interstitial and vacancy loops with b = ⅓〈1120〉 nucleate and grow. In addition, vacancy loops with b = ½[0001] and interstitial loops with b = ⅓〈1123〉 are observed in foils having normals N close to [0001] and 〈1210〉, respectively. There is a partitioning in the Burgers vecctor of all loops such that vacancy loops generally tend to have b as nearly parallel as possible to N, and interstitial loops tend to have b perpendicular to N. This effect is most marked for c component loops and is related to a tensile stress generated in the plane of the foil during oxidation of thin foils. These observations are discussed in terms of irradiation-induced growth.