The solute dependence of bias factors in irradiated Fe-Ni alloys

The interstitial and vacancy biases for an edge dislocation in a binary alloy were examined, assuming the existence of an equilibrium Cottrell 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 offers a plausible explanation for the minimum in swelling observed at intermediate nickel levels and the gradual increase in swelling at higher nickel levels. (orig.)