99.999 mass%アルミニウム多結晶における動的再結晶

Abstract

Constant-compression speed testing was performed using a 99.999 mass% aluminum polycrystal with a grain size of 1.0 mm at temperatures ranging from 413 to 653 K and initial strain rates ranging from 1.67×10−1 s−1 to 1.67×10−5 s−1. The true stress-true strain curves showed a variation from 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 grains containing subgrains were observed in the specimens showing stress oscillations. The stress oscillations were assessed to be caused by dynamic recrystallization. The dynamic recrystallization takes place around the first peak stress of the stress oscillation at an initial strain rate of 1.67×10−3 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.