Calculated Point Defect Properties of the Intermetallic Compounds Nickel Titanium (NiTi) and Iron Titanium (FeTi).

摘要

Atomistic simulation with a modified version of the DYNAMO code was used to calculate the point defect properties of the intermetallic compounds nickel titanium and iron titanium. The calculated energies are believed to be experimentally accurate to within +/- 0.1 eV. Vacant Ni or Fe lattice sites were preferred and had energies of 6.356 eV for NiTi and 5.899 eV for FeTi. Removing a Ti atom resulted in a neighboring antisite defect caused by migration of a Ni or Fe atom into the vacant Ti site. These configurations had energies of 7.024 eV for NiTi and 6.336 eV for FeTi. The calculated vacancy defect formation energies were 1.48 eV for NiTi and 1.07 eV for FeTi. The interstitial defect configurations consisted of Ni-Ni or Fe-Fe split-interstitial dumbbells centered on a Ti site with one or two adjacent Ti antisite defects. Ti interstitials resulted in two adjacent Ti antisite defects with a <011> Fe-Fe dumbbell or a <111> Ni-Ni dumbbell. These Ti interstitial energies were -2.395 eV for NiTi and -1.558 eV for FeTi. Ni or Fe interstitials both resulted in an adjacent Ti antisite defect with Ni-Ni or Fe-Fe <111> oriented dumbbells. The Ni or Fe interstitial energies were -2.602 eV for NiTi and -1.945 eV for FeTi.