Threshold displacement and interstitial-atom formation energies in Ni₃Al

Threshold displacement energies for atomic displacements along 〈110〉, 〈100〉, and 〈111〉 directions, and formation enthalpies of several symmetric interstitial atom configurations were calculated for Ni₃Al by computer simulation using “embedded atom method” potentials. The Ni–Ni (100) dumbbell in the plane containing only Ni atoms has the lowest interstitial-atom enthalpy although the enthalpies of other configurations are similar. Interstitial configurations involving Al atoms all have much higher enthalpies. The anisotropy of the threshold energies in Ni₃Al is similar to pure metals and no significant difference in threshold energy was observed for 〈110〉 replacement chains in rows containing all Ni atoms or alternating Ni–Al atoms. Various metastable interstitial atom configurations were observed, including crowd-ions. In addition, the spontaneous recombination volume for some configurations can be much smaller than in pure metals. The consequences of these results for radiation induced segregation and amorphization are discussed.