HOT DEFORMATION MECHANISMS IN Mg-x percent Al -1 percent Zn -y percent Mn ALLOYS

摘要

To investigate the hot deformation and fracture characteristics of Mg-1wt percent Zn alloys containing a range of Al and Mn levels, hot-rolled specimens were tensile tested over a range of strain rates and temperatures. Strain rate versus flow stress diagrams plotted on log-log scales revealed a transition in deformation mechanisms as a change in slope. Specifically, non-uniform (necking) thinning is observed at high strain rates, while uniform thinning is observed at low rates. This transition is accompanied by a change in fracture mechanism from dimpled rapture at high strain rates to cavitation and cavity interlinkage at low rates. There does not appear to be an effect of Al on this behaviour. However, Mn appears to favor the uniform elongation regime, since the onset of cavitation appears at higher strain rates compared to alloys without Mn.