RESTORATION MECHANISMS IN LARGE-STRAIN DEFORMATION OF HIGH-PURITY ALUMINUM AT AMBIENT-TEMPERATURE AND THE DETERMINATION OF THE EXISTENCE OFSTEADY-STATE

High purity (99.999%) aluminum was deformed at ambient temperature to large strains in compression at strain rates of 10(-3) and 10(-5) s-1. A saturation in the flow stress is eventually observed at both rates, but this is followed by significant softening. Analysis of the mechan ical tests, optical microscopy, and transmission electron microscopy s uggest that the softening is due to recrystallization during deformati on. Some early investigations that report a steady-state in high purit y aluminum, suggesting a balance between dynamic recovery and hardenin g, may have actually been a result of recrystallization. Other investi gations that report a continual, Stage IV, hardening with an absence o f a saturation of the. flow stress or a steady-state, even at large st rains, may be valid for cases where recrystallization is suppressed.