镁合金因其密度低、比强度高等优点，在航空航天、汽车工业和电子产品中得到广泛应用。 然而，镁合金的 耐蚀性能较差，限制了其应用。 为改善镁合金的耐蚀性，本文采用Bi和Gd元素进行合金化处理，并通过反向挤压工艺 制备了Mg-1Bi-0.5Gd (0.94%Bi, 0.53%Gd，质量分数)合金。 通过 XRD、OM、SEM、析氢实验和电化学测试，研究了挤压 前后Mg-1Bi-0.5Gd 合金的微观组织和腐蚀行为的变化。 结果表明，与均匀态合金相比，挤压态Mg-1Bi-0.5Gd合金表现 出更高的腐蚀电位和更低的腐蚀电流密度，显示出更优异的耐蚀性。这是由于挤压工艺细化了合金的晶粒组织，显著提 升了耐蚀性能。

Magnesium alloys are widely used in aerospace, automobile and electronic products because of their low density and high specific strength. However, the poor corrosion resistance of magnesium alloys limits their application. To improve the corrosion resistance of magnesium alloys, Bi and Gd were used for alloying, and a Mg-1Bi-0.5Gd (0.94 wt. %Bi, 0.53 wt. %Gd) alloy was prepared via a reverse extrusion process. The microstructure and corrosion behavior of the Mg-1Bi-0.5Gd alloy before and after extrusion were studied via XRD, OM, SEM, hydrogen evolution experiments and electrochemical tests. The results show that, compared with the homogeneous alloy, the extruded Mg-1Bi-0.5Gd alloy has greater corrosion potential and a lower corrosion current density, resulting in better corrosion resistance, which is attributed to the extrusion process further refining the grain structure of the alloy and significantly improving its corrosion resistance. Key words： reverse extrusion; Mg-1Bi-0.5Gd alloy; electrochemistry; grain refinement.