Softening behavior of nanocrystalline Mg-6Al-1Zn-1Si alloy during mechanical alloying

Document Type: Original Paper


Department of Material Science and Engineering, Faculty of Mechanical Engineering, Babol Noshirvani University of Technology, P.O.Box 47148-71167, Shariati Street, Babol, Iran


Mg, Al, Zn and Si elemental powder mixtures were subjected to high-energy milling to produce Mg-6Al-1Zn-1Si (wt %) alloy. The milled powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness measurement. The Mg grain size was estimated from the broadening of XRD peaks using Williamson-Hall method. The results showed that the solubility of alloying elements in Mg extended compared to the equilibrium value with increasing the milling time up to 35 h. However, after longer milling time of 50 h, the hardening due to the decreasing grain size compete with softening due to the decomposition of supersaturated solid solution, leading to a decrease in hardness value of as-milled powder.