Atomistic simulations of point defects in ZrNi intermetallic compounds

The properties of point defects, including stable configurations, formation and migration energies, and migration mechanisms. in the ZrNi and Zr2Ni in termetallic compounds were simulated using molecular dynamics and statics, in conjunction with interatomic potentials derived from the Embedded Atom M ethod. We describe a method to calculate the formation energy of point defe cts from the program and apply the method to ZrNi and Zr2Ni. The results sh owed that vacancies are most stable in the Ni sublattice, with formation en ergy of 0.83 and 0.61 eV in ZrNi and Zr2Ni, respectively. Zr vacancies are unstable in both compounds; they spontaneously decay to pairs of Ni vacancy and antisite defect. The interstitial configurations and formation energie s were also calculated, with similar behaviors. In ZrNi, vacancy migration occurs preferentially in the [0 2 5] and [1 0 0] directions, with migration energy of 0.67 and 0.73 eV, respectively, and is essentially a two-dimensi onal process, in the (001) plane. In Zr2Ni. vacancy migration is one-dimens ional, occurring in the [0 0 1] direction, with a migration energy of 0.67 eV. In both compounds, the presence of Ni antisite defects decreases the Ni vacancy migration energy by up to a factor-of-three, and facilitates three -dimensional motion. (C) 2001 Elsevier Science B.V. All rights reserved.