By using computer simulations, it was shown that the difference in the formation energy of a self-interstitial atom and a vacancy was the basic cause of dislocation bias. In the case of production bias, detailed information on interstitial clusters was required and it was found that - in an Fe model lattice - that the edge dislocation line had a special characteristic: a periodicity of b/3. In the case of dislocation loops, these stable positions - distributed with a periodicity of b/3 - diffused out with decreasing loop size and tended to have a periodicity of almost b in the lower limits of loop size. This suggested that the Peierls potentials which dislocation loops had to overcome depended upon the loop size. That is, a smaller Peierls stress could be expected for larger loops and an edge dislocation line; probably because of a finer-periodicity b/3 value. At finite temperatures, small clusters of crowdions tended to have a rather loose coupled structure of composite crowdions and slip motion of a whole cluster was not well-defined. The diffusion process as a whole might then better represent the motion of small clusters at high temperatures.

Bias Mechanism and Its Effects for Fundamental Process of Irradiation Damage. E.Kuramoto, K.Ohsawa, J.Imai, K.Obata, T.Tsutsumi: Materials Transactions, 2004, 45[1], 34-9