Microstructure and Mechanical Properties of Magnesium-Aluminium (Mg-Al) Alloys with High Aluminium Content (Al =10, 15, 20 wt. %)

Abstract

Magnesium-Aluminium (Mg-Al) alloys containing zinc or manganese are preferred choice in automobile and aerospace sectors. Aluminium, the major strengthening element in Mg-alloys is always added below its solid solubility limit of 12.5 wt.%. In the current study, Mg-Al binary systems with Al-content just below and above the solubility limit (Al = 10, 15 and 20 wt.%,) were developed and examined for their microstructural and mechanical behaviour. Microstructural studies showed the importance of Al-content in determining: (i) grain size reduction and (ii) distribution and amount of inter metallic phase. Mechanical property evaluation showed that the hardness increase was linearly dependent on Al-content, with Mg-20Al showing > 250% increase in hardness than commercial AZ91alloy. Mg-10Al showed 215% and 130% increase in yield and ultimate strengths respectively, and exhibited the best properties in terms of work of fracture, which is representative of the alloy’s toughness.