The damage which was produced by displacement cascades in this L12 alloy at 100K was investigated by using molecular dynamics methods and many-body interatomic potentials. Cascades which ranged in energy from 0.15 to 5keV were simulated in order to study the effects of the energy and type of primary recoil atoms. Computer-generated color plots were used to visualize the nature and arrangement of the point defects which were produced in the cascade events. It was found that there was a change in the cascade morphology, at the end of the collisional phase, for cascade energies ranging from 1 to 2keV. Separate sub-cascade regions could be seen in some cascades at 5keV. Individual replacement sequences did not make a significant contribution to the final damage state. The efficiency of production of Frenkel pairs declined, with increasing cascade energy, in a similar fashion to that observed recently in pure metals. Some 90% of the interstitials which were created in cascades were Ni-Ni dumb-bell atoms, and the tendency of interstitials to form clusters was weaker than that observed in pure metals. Antisite defects were much more numerous than Frenkel pairs, and their production efficiency increased with increasing cascade energy. These results were in general agreement with those which had previously been obtained by modelling 5keV cascades; apart from the numbers of antisite defects which were found. Finally, a published simulation of the displacement threshold at 0K was here extended to 100K in order to investigate the effect of temperature upon the displacement threshold energy under conditions that were consistent with cascade modelling.

Molecular Dynamics Study of Displacement Cascades in Ni3Al I. General Features and Defect Production Efficiency. Gao, F., Bacon, D.J.: Philosophical Magazine A, 1995, 71[1], 43-64