Retardation of the precipitation reaction by d.c. stress in an Al-12.5 wt % Zn alloy

The effect of direct electric current stress on the precipitation reaction in an Al-12.5 wt % Zn alloy was investigated by the resistometric method. It was found that the d.c. stress retarded the reaction rate as in the case of an Al-4 wt% Cu alloy. The dependence of the retarding effect on the annealing time and on the quenching temperature was examined on the basis of a model of current-assisted vacancy annihilation. The annealing temperatures after quenching were 30 and 40° C, and the quenching temperatures were varied from 300 to 500° C.