Microstructures and mechanical properties of AZ31 magnesium alloys fabricated via vacuum hot-press sintering

Magnesium and its alloys have become attractive materials in automotive and aerospace fields because of their low density and high strength. However, their application is greatly limited by their poor deformation capacity. Powder metallurgy technology can reduce the deformation and processing of magnesium alloys during the preparation process to alleviate this problem because of its near net shape machining characteristics. In this paper, a high-performance AZ31 magnesium alloy was prepared via vacuum hot-press sintering. The effects that sintering temperature has on the structure and mechanical properties of the as-sintered alloy were investigated. The results indicate that the sintered microstructure is composed of approximately equiaxed α-Mg crystal grains, and nanoscale Al-Mn phases precipitated in the crystals and particle boundaries. At an optimal sintering temperature of 535 °C, the average tensile strength, compressive strength, elongation, and fracture strain of the sample are 247.10 MPa, 391.35 MPa, 22.27%, and 24.17%, respectively. In addition, the reasons for the high strength and favorable elongation of the AZ31 magnesium alloy that was sintered via vacuum hot pressing were also analyzed. This is mainly because pressure is applied during the sintering process; this eliminates pores and breaks the oxide film on the powder surface, thereby forming a good metallurgical bond between the powders.