Analysis of growth rates of voids in the matrix and at precipitates in irradiated alloys

A characteristic feature of irradiated complex alloys is the correlated evolution of voids, dislocations and seconday phase precipitates, with the largest voids often adjacent to precipitates. Two mechanisms can be responsible for enhanced growth of voids at precipitates. The collector mechanism considers the whole surface of the pair void—precipitate as a point defect sink. The segregation mechanism accounts for the difference in radiation-induced segregation near free voids and voids at precipitates and corresponding difference in segregation-induced biases. In this paper a kinetic model for size distribution functions of isolated voids and voids adjacent to precipitates is developed. By fitting the model calculations to experimental data, the effective bias of voids at G-phase precipitates in neutron-irradiated 12Cr 15Ni steel is calculated and compared with predictions of collector and segregation mechanisms. The effect of precipitates on swelling rate of alloys is analysed.