Effects of heat treatment and plastic deformation on structure and properties of Mg-9Al-1.2Nd-0.45Y-0.7Zn Mg alloy

The experiments of heat treatment, hot extrusion and hard drawing were employed to study their effects on the structure and mechanical properties of Mg-9Al-1.2Nd-0.45Y-0.7Zn magnesium alloy. The results indicate that the mechanical properties of the ingot are unstable and exhibit typical brittle failure. After heat treatment (693K, 24h), most β-Mg17Al12 phases decomposed into the α-Mg matrix and the distribution of Rare earths compounds remained the state of as-cast, which have little effects of the mechanical properties of the alloy. As the casting defects disappeared and the grain was refined after hot extruded, the mechanical properties of the alloy were drastically increased. By hard drawing, the ultimate tensile strength and the yield strength of the alloy were sharply increased while the elongation decreased rapidly. The failure of as-cast samples was mainly brittle fracture. After plastic deformation, the fracture patterns all exhibited ductile rupture features.