Effect of heat treatment variables on the formation of precipitate free zones (PFZs) in Mg-8Al-0.5Zn alloy

The present study is focussed on investigating the effect of heat treatment variables on the formation of precipitate free zones (PFZs) in the AZ80 Mg alloy. The effect of solutionizing temperature, quenching media, aging temperature and time on the PFZ development has been systematically examined. Scanning electron microscopy and nanoindentation were employed to characterize the PFZ regions. Electron probe micro analysis (EPMA) was used to examine the role of solute depletion in the formation of these zones. Moreover, the estimation of vacancy concentration profiles near the grain boundary was used to investigate the role of vacancy depletion. The solute depletion is found to be the dominant mechanism in the development of PFZ regions as compared to vacancy.