Effect of the Solid-Solution Treatment on the Die-Casting Structures and Properties of Commercial RE-AZ91 Mg Alloy
Effect of the solid-solution treatment on the casting structures and properties of the die-casting Mg alloy was explored through the way of adding mixed rare earths Y, Gd and Nd into the commercial Re-AZ91 Mg alloy . The results show that the solid-solution treatment could improve effectively the microstructures of the alloy, and Mg17Al12 phrase on the grain boundaries could transform from network struture into dotlike or granular one. At the same time, the compounds on the grain boundaries were less than those before the solid-solution treatment, the compounds were dispersed inside the grain . Both the microstructures and the mechanics properties of the alloy could be improved remarkably, and also, the tensile strength σb could reach over 280MPa, the elongation ratio δ over 9% when the temperature of the solid-solution treatment was between 270°C and 410°C. When the temperature of the solid-solution treatment exceeded 420°C, coarse Al-RE compounds would be formed inside the alloy, which could reduce the mechanics properties of AZ91 Mg Alloy.