Numerical calculations were made of the capture efficiency of a dislocation loop in a finite toroidal reservoir. This was a more appropriate model for a dislocation loop than was the spherical or cylindrical reservoir adopted in previous models. It permitted a direct evaluation of the capture efficiency and the bias for a loop of any size; with full account being taken of the stress field in the loop region of influence. It was shown that the loop bias depended upon the loop size, dislocation density and the interstitial to vacancy dilatation ratio. With increasing loop size, its bias decreased or increased relative to the straight dislocation bias value if the dislocation density was low or high, respectively. The bias difference of loops of different sizes was shown to be the cause of the coexistence of vacancy and interstitial loops under irradiation. In the conventional case of dislocation bias for interstitials, the interstitial loops were expected to grow to larger sizes than vacancy loops. In the special case of a dislocation bias for vacancies, the opposite tendency was expected.

Numerical Evaluation of the Dislocation Loop Bias. V.I.Dubinko, A.S.Abyzov, A.A.Turkin: Journal of Nuclear Materials, 2005, 336[1], 11-21