PNNL

Abstract

The effects of using different interatomic potentials in molecular dynamics (MD)simulations of the formation of He-vacancy clusters within displacement cascades in a-Fe are investigated using two sets of potentials. Simulations of cascades produced by primary knock-on atoms (PKA) of energy Ep = 1-20 keV were performed in a-Fe containing a concentration of substitutional He atoms varying from 1 to 5 at.% at an irradiation temperature of 100 K. Although the effects of interatomic potentials on the nucleation of He-vacancy clusters induced by cascades are relatively small, the number and size of He-vacancy clusters produced are significantly different for the different potentials employedin this study. Thus, these differences may influence the microstructural evolution predicted in damage accumulation models that use the results from MD cascade simulations as input. The observed differences in post-cascade configurations can be attributed mainly to the differences in the Fe-Fe and Fe-He potentials.