Abstract
The tensile behavior of a powder metallurgically processed Al-5mass%Mg-2.2mass%Mn alloy with a fully recrystallized fine grained structure of 3 μm in size was characterized at strain rates between 10-4 and 2 s-1 at temperatures from 748 to 823 K. This alloy exhibited superplasticity at high strain rates around 10-2 s-1. A maximum elongation of 570 % was obtained at a constant strain rate of 6x10-3 s-1 at 823 K. An analysis of the threshold stress indicated that the true stress exponent is 2 for all testing temperatures and the true activation energy for superplastic flow is equal to that for lattice diffusion in aluminum. It is postulated that superplastic flow in the P/M Al-Mg-Mn alloy is controlled by a grain boundary sliding mechanism accommodated by dislocation climb or glide controlled by lattice diffusion.
