New insights on the mechanisms controlling the nickel dependence of swelling in irradiated Fe-Cr-Ni alloys

In a previous report the interstitial and vacancy biases for an edge dislocation in a binary alloy were examined, assuming the existence of an equilibrium Cottrel atmosphere around the line defect. The Larche' and Cahn treatment of stress relaxation due to a solute atmosphere was employed with the Wolfer and Ashkin formulation for the bias of an edge dislocation to compute the bias as a function of nickel concentration in the Fe-Ni system. Using the minimum critical void radius concept, the concentration-dependent bias was shown to offer a plausible explanation for the minimum in swelling observed at intermediate nickel levels and the gradual increase in swelling at higher nickel levels. In this report, a more realistic description of the composition dependence of vacancy diffusion has also been included, an addition which improves the model substantially. 18 refs., 8 figs