The effect of homogenization annealing on the structure and mechanical properties of magnesium alloys of the Mg-1Zn-XCa system

Abstract

In this paper, the evolution of microstructure and mechanical properties of magnesium alloys Mg-1Zn-0.05Ca and Mg-1Zn-0.3Ca after homogenization annealing was investigated. Microstructure studies have shown that the homogenization anneal results in a significant increase in grain size. In the Mg-1Zn-0.05Ca alloy, the average grain size increased by 42% from ~530 μm in the cast state to 750 μm after annealing for 24 h at T = 450 °C. In the Mg-1Zn-0.3Ca alloy, the average grain size increased by 90% from ~330 μm in the cast state to 630 μm after 24 hours annealing. Despite the increase in grain size, the ultimate tensile strength of the alloys after annealing increased compared to the cast state. Such an effect may be primarily due to the transition of zinc atoms into solid solution and the increased contribution of solid solution hardening. The results of mechanical tensile tests showed that the mechanical properties of magnesium alloys vary with the duration of annealing. Homogenization annealing has been shown to improve the ductility of magnesium alloys. Homogenization annealings of the Mg-1Zn-0.3Ca alloy promoted spheroidization of the particles, which had an elongated shape in the cast state.