Point Defect Dynamics in Nonhomogenous Alloys Under Irradiation

Abstract

With the aid of a simple reaction model for point defects in a nonhomogenous alloy, we show that large-scale point defect fluxes are to be expected under irradiation. The model is solved analytically in the limit of low-amplitude concentration fluctuations of sinusoïdal shape, under steady state conditions. We give expressions for the defect fluxes as a function of the irradiation intensity, the amplitude and wavelength of the composition fluctuation. It is shown that from the difference of the interstitial and vacancy fluxes a bias for defect elimination results, which is modulated at the scale of the chemical inhomogeneity. The latter bias, as estimated here, depends on the irradiation flux extremely weakly. Orders of magnitude of the defect fluxes and redistribution are given for the FeNiCr system. It is shown qualitatively that the implied processes have the proper direction to sustain the composition inhomogeneities, which have been reported in such alloys after irradiation.