Point defect energetics in the ZrNi and Zr 2Ni intermetallics

Abstract

A systematic study of the properties of point defects has been conducted in the ZrNi and Zr 2Ni intermetallic compounds using molecular dynamics. These properties include the stable defect configurations, formation and migration energies, and vacancy migration mechanisms. Zr vacancies (interstitials) are unstable in both compounds; they spontaneously decay to pairs of Ni vacancy (interstitial) and antisite defect. The stable Ni vacancies have formation energies of 0.83 and 0.61 eV in ZrNi and Zr 2Ni, respectively. In ZrNi, vacancy migration occurs preferentially in the [0 2 5] and [1 0 0] directions, with migration energies of 0.67 and 0.73 eV, respectively, and is essentially a two-dimensional process, in the (0 0 1) plane. In Zr 2Ni, vacancy migration is one-dimensional, occurring in the [0 0 1] direction, with a migration energy of 0.67 eV. The stable interstitial configurations for both compounds consist of a Ni atom lying on the (0 0 1) plane between two out-of-plane nearest-neighbor Zr atoms.