Temperature dependence of tensile elongation in a mechanically milled, P/M Al-Mg-Cu alloy

A mechanically milled and thermo-mechanically treated Al-1.1Mg-1.2Cu (at%) alloy exhibits superplastic elongation at an intermediate temperature of 748K, neither at higher nor lower temperatures, and a large portion of total elongation is accounted for by the grain deformation. Computer simulation of stress-strain behavior from a viewpoint of dislocation dynamics indicates that a combination of the largest re-mobilization probability of immobile dislocations, the highest mobile dislocation density and the modest immobilization rate of dislocations is responsible for the largest elongation at 748K.