Dynamaic recrystallization of 99.999 mass% aluminum polycrystal

Constant-compression speed testing was performed using a 99.999 mass% alumi num polycrystal with a grain size of 1.0 mm at temperatures ranging from 41 3 to 653 K and initial strain rates ranging from 1.67 x 10(-1) s(-1) to 1.6 7 x 10(-5) s(-1). The true stress-true strain curves showed a variation fro m a single peak type to multipeak type with increasing temperature and with decreasing strain rate. The apparent activation energy for the deformation was measured from the temperature and strain rate dependence of the first peak stress. The value was 136 kJ mol(-1) which is nearly the same value as the activation energy for the self-diffusion of aluminum. Recrystallized g rains containing subgrains were observed in the specimens showing stress os cillations. The stress oscillations were assessed to be caused by dynamic r ecrystallization. The dynamic recrystallization takes place around the firs t peak stress of the stress oscillation at an initial strain rate of 1.67 x 10(-3) s(-1) and at 513 K. The dynamically recrystallized grain size at a strain of 1.0 decreases linearly with increasing Zener-Hollomon parameter Z .