Bias Mechanism and Its Effects for Fundamental Process of Irradiation Damage

Abstract

In order to obtain the better understanding for bias effects under irradiation computer simulation was made and the basic view for the dislocation bias was presented from the formation energy of radiation induced defects. It was shown that the difference of the formation energy between a self-interstitial atom and a vacancy is the most basic origin for the dislocation bias. On the other hand, for the production bias the detailed information on interstitial clusters is required and it was found in Fe model lattice that the edge dislocation line has a special character, i.e., a periodicity of b/3, but in the case of dislocation loops these stable positions distributed with a periodicity b/3 diffuse out with decreasing loop size and tend to have a periodicity of nearly b in the smaller limit of loop size. This behavior suggests that Peierls potentials which dislocation loops must overcome depend upon the loop size, and smaller Peierls stress can be expected for larger loops and an edge dislocation line probably because of finer periodicity b/3. But at finite temperatures small clusters of crowdions easily tend to have a rather loose coupling structure of composing crowdions, and slip motion as a whole cluster is not well defined, and the diffusion process as a whole might be better to represent the motion of small clusters at high temperatures.