Influence of Composition on Steady-State Void Nucleation in Irradiated Alloys

Abstract

The major features of the compositional dependence of radiation-induced swelling of iron-nickel-chromium and iron-nickel-chromium-silicon alloy systems are reproduced using a model proposed by Garner. The model asserts that the major compositional dependence of radiation-induced swelling can be explained by the compositional dependence of the effective vacancy diffusion coefficient, Dveff. The primary influence of composition resides in the transient regime of swelling and is related to the effect of Dveff on the rate of void nucleation. Measured variations in elemental diffusivities with composition and temperature are used along with the KWR nucleation theory to calculate the steady-state void nucleation rate. The nucleation rate is inversely proportional to the duration of the transient regime at any given temperature. Void nucleation rate is found to depend strongly on the silicon content, and to a lesser extent on the nickel and chromium contents.