Theoretical evaluation of a mechanism of precipitate-enhanced cavity swelling during irradiation

Abstract

It is often observed experimentally in complex alloys, such as the austenitic stainless steels, that the largest cavities produced during irradiation are attached to second-phase precipitate particles. One hypothesis that such observations suggest is that the precipitate—matrix interface may assist in the collection of irradiation-produced point defects which are channelled to the attached cavities. A theoretical analysis is developed to evaluate this mechanism. It is found that the growth of cavities attached to precipitates is increased compared to the growth of cavities in the matrix. The relative growth rates of the two types of cavity are also affected by differences in bias and differences in sink strength. The relationships required to evaluate these effects are developed and the consequences of enhanced point-defect collection are explored in some detail. For the parameter range of interest, it is found by calculation that the cavity attached to the precipitate may grow several times larger than the cavity isolated in the matrix. Simple experiments are suggested and the expected results are described for comparison.