Abstract:The effect of adding 1% Sn on the corrosion resistance of homogeneous Mg-6Zn-0.25Ca alloy was studied. The corrosion resistance of Mg-6Zn-Sn-0.25Ca(1k) and Mg-6Zn-0.25Ca(10k) alloys was analyzed by OM, XRD, SEM, hydrogen evolution weight loss and polarization curve experiments. The results show that the main second phase of Mg-6Zn-0.25Ca(10k) alloy is Mg2Ca phase, and after the addition of Sn element, the main mode of existence of the second phase in Mg-6Zn-Sn-0.25Ca alloy is Mg2Sn phase, Mg2Ca phase and a small amount of CaMgSn phase. The addition of Sn element enhances the corrosion resistance of Mg-6Zn-0.25Ca alloy, and the second phase of the alloy is more evenly distributed after the addition of Sn element, and the average grain size of the alloy decreases from 145.6um to 114.2um, because the Mg2Sn phase with high melting point can be used as a heterogeneous nucleation core for non-spontaneous crystallization of the α-Mg matrix, thereby refining the grain size. Under the combined effect of the two, the oxide film produced by the corrosion of the alloy is more dense, preventing the hydrogen evolution reaction from proceeding. In addition, the polarization curves show that the self-corrosion potential and self-corrosion current density of Mg-6Zn-0.25Ca alloy are -1.729V and 2.106×10-5 μA/cm2, respectively, and the self-corrosion potential increases to -1.525V and the self-corrosion current density decreases to 8.561×10-6μA/cm2, which enhances the corrosion resistance of Mg-6Zn-Sn-0.25Ca alloy.