Calculations of the properties of single and multiple defects in nickel

The properties of single and multiple defects in Ni were calculated by molecular dynamics simulation using an effective interaction potential derived with the aid of a new method developed by Dagens for transition metals. The formation and migration energies of single vacancies are 1.33 and 0.90 eV, respectively. Di-, tri- and tetravacancies are weakly bound, with respective binding energies of 0.004, 0.10 and 0.24 eV. The divacancies are more mobile than the single vacancies, having a migration energy of 0.47 eV. Self-interstitials are found to be stable in the (100) dumbbell configuration; their energies of formation and migration are 4.16 and 0.12 eV, respectively. Multiple interstitials are strongly bound; like the single dumbbell interstitials, di-interstitials are highly mobile. The respective binding and migration energies for di- and tri-interstitials are 1.13 and 0.17 eV, and 2.67 and approximately 0.50 eV. The theoretical results are compared with the available experimental measurements and with previous defect calculations based on a short-range empirical potential.