Effect of uniaxial stress on the threshold displacement energy of silicon carbide

Abstract

Silicon Carbide (SiC) is a very promising nuclear material. Understanding the effect of stress field on the irradiation damage behavior of SiC is crucial for the actual service. Numerous experiment and simulation studies have revealed the fundamental irradiation damage mechanism in non-stress SiC. We can learn from the previous simulation studies that though several limits and inaccuracies in calculating the threshold displacement energy(Ed) have been reported, molecular dynamics (MD) methods are still considered valid in general. In this work, we calculate the Eds of both the elements in SiC along 5 primary crystallographic directions under 13 kinds of uniaxial stress fields using the MD method. The Eds obtained under the non-stress condition are consistent with previous research works. The rules of Eds changing with the deformation are discussed in detail, and the corresponding displacement process and displacement configurations are also analyzed. In general, Eds decrease with the increase in deformation whether it is stretching or compressing. Under relatively high stress field, the reduction of Ed is significant, and the anisotropy of Ed also greatly reduces. A transition of preferred displacement configuration from octahedral interstitial to tetrahedral interstitial is reported and discussed.