Effects of solution treatment on microstructure, mechanical properties and corrosion behavior of Mg-2Zn-1Y-0.5Zr alloy

Abstract

The effects of solution treatment on microstructure, mechanical properties and corrosion behavior of Mg-2Zn-1Y-0.5Zr alloy were investigated by optical microscope (OM), scanning electron microscope (SEM), confocal laser scanning microscope (CLSM), x-ray diffraction (XRD), tensile tests, electrochemical test and immersion test. The results indicated that the as-cast alloy was comprised of an equiaxed α-Mg matrix, I-phase, W-phase and MgZn2 phase. After solution treatment at different temperatures, the second phase gradually dissolved into the magnesium matrix, and the grain size of the alloy increased to different degrees. The alloy solution-treated at 420 °C for 10 h had better mechanical properties, and its tensile strength, yield strength and elongation were 195.0 ± 5.4 MPa, 97.3 ± 1.9 MPa and 25.8 ± 0.4%, respectively. The alloy solution-treated at 440 °C for 10 h had better corrosion resistance and its corrosion rate was 0.304 ± 0.021 mm y−1. The best mechanical properties and corrosion resistance can be obtained by balancing the volume fraction of the second phase and grain size. The alloy after solution-treated at 440 °C for 10 h has the best comprehensive properties.