Incorporation of the Suzuki and the Fisher interactions in the analysis of creep behavior of solid solution alloys

Abstract

The earlier analysis of predicting the creep class behavior (whether viscous glide-controlled creep or climb-controlled creep) of a particular solid solution alloy is extended to take into account the situation in which the contributions of solute atom-dislocation interactions such as the Suzuki and the Fisher interactions to the dragging force acting on the dislocations during glide are significant and comparable with that provided by the Cottrell-Jaswon interaction. Calculations based on structural parameter values, such as stacking fault energies, local order coefficients and atom misfit ratios, of many solid solution systems indicate that this situation may exist in a number of alloys. Among these alloys are Fe18at.%Al, Al30at.%Zn, Ni25at.%Fe, Al10at.%Ag, Cd10at.%Mg and Ag18at.%Zl. By examining the creep data of several AlZn alloys and an Ni25at.%Fe alloy, it is shown that the class of behavior of these alloys, as inferred from the values of the stress exponent, can be accounted for by the present analysis which considers the contributions of the Suzuki and the Fisher interactions and not by the earlier analysis which assumes that solute drag forces arise only from the Cottrell-Jaswon interaction. The role of the appropriate diffusion coefficient for describing the creep behavior in the correlation between experiment and prediction is discussed in the light of very recent suggestions.