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

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. (paper)