The effects of an applied stress upon the early stages of interstitial-type Frank loop evolution were investigated by means of numerical calculations and irradiation experiments. The object was to develop a comprehensive model for the complex effects of stress upon microstructural evolution under various conditions. Microstructural analyses revealed that differences in the resolved normal stress led to differences in the nucleation rate of Frank loops on {111} planes. The total nucleation rate of Frank loops increased with increasing external applied stress. Numerical calculations were carried out in order to evaluate various models for the effects of stress upon nucleation during Frank loop evolution. The calculation depended upon the use of rate equations which described the evolution of point defects, small point-defect clusters and Frank loops. The rate equations for Frank loop evolution were derived for {111} planes, and took separate account of the effects of a resolved normal stress upon the clustering of small point defects and the growth of Frank loops. The experimental results and the predictions of numerical calculations agreed well in a qualitative sense.

H.Tanigawa, Y.Katoh, A.Kohyama: Nuclear Instruments and Methods in Physics Research B, 1995, 102[1-4], 151-5