Effects of Zn Addition on Microstructure, Mechanical, and Corrosion Properties of the As-Solutionized Mg-5Ga Alloy

The work uses the optical microscopy (OM), scanning electron microscopy (SEM), tensile testing, immersion testing, and electrochemical measurement to analyze the effects of the Zn addition (0, 0.3, 0.6, 0.9 and 1.2 mass%) on microstructure, mechanical, and corrosion performance of the as-solutionized Mg-5Ga alloy. The addition of Zn can bring about finer grain size, higher tensile strength, and bigger breaking elongation in the Mg-5Ga alloy. The as-solutionized Mg-5Ga-1.2Zn alloy shows optimal comprehensive mechanical performance with the ultimate tensile strength of 260 ± 2.4MPa and ultra-high plasticity (the breaking elongation of 40.3 ± 0.3%). Grain refinement and solution strengthening are mainly conducive to the improvement in strength. Moreover, adding Zn element enhances anticorrosion property of the as-solutionized Mg-5Ga alloy, wherein the as-solutionized Mg-5Ga-0.9Zn alloy has the optimal anticorrosion property in 3.5% NaCl solution, in close relation with finer grain size and more protective corrosion film.