Time evolution of agglomerate size of semisolid magnesium alloy AZ91D during a real isothermal shearing

Abstract

Abstract The present study attempts to discuss the time evolution of the slurry microstructure of semisolid magnesium alloy AZ91D so as to control the forming process more effectively. We calculated the instantaneous shear stress and the time evolution of average agglomerate size of a real isothermal shearing process containing increasing shear rate, holding the maximal shear rate and decreasing shear rate. The calculated results demonstrate that we should adopt as great a maximal shear rate as possible to achieve a finer slurry microstructure and reduce the resulting larger startup shear stress by increasing the time interval required to increase the shear rate to maximum. Moreover, we also should shorten the time interval required to decrease the shear rate to zero as far as possible, so as to weaken agglomeration during decreasing shear rate and achieve a better final slurry microstructure.