Superplastic behavior and deformation mechanisms of Al-Mg-based alloy processed by isothermal multidirectional forging

The evolutions of microstructure and superplastic deformation mechanisms for Al-Mg-based alloy with L12nanoprecipitates and recrystallized 1.8 mu m grains processed by multidirectional forging were studied. The alloy exhibiting excellent superplastic properties at 460 degrees C high strain rates of (1-6) x 10- 2s- 1. Due to a high fraction of high-angle grain boundaries and grain size stability, grain boundary sliding contributed -50 % to the total strain and it was accommodated by both dislocation slip/creep and diffusional creep mechanisms. The dislocation slip/creep contribution increased with increasing strain rate.