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系统研究了Mg-5Gd-3Y-0.8Zr合金的微观组织和耐蚀性能,通过静态失重法测定了其在NaCl溶液中的腐蚀速率。结果表明:铸态合金主要由基体α-Mg和方块状β相(Mg_5Gd、Mg_(24)Y_5)组成,时效处理后分布在晶界处的共晶β相数量明显增加;在NaCl溶液中腐蚀12 h以后镁合金的腐蚀速率明显增加,在3.5%Na Cl(质量分数)溶液中腐蚀24 h后,镁合金已被严重腐蚀,表面布满腐蚀坑和未脱落的白色腐蚀产物;镁合金易产生沿晶腐蚀,方块状共晶β相颗粒可有效阻止表面腐蚀沿晶界向镁合金内部扩展,从而提高镁合金的耐蚀性。
The microstructure and corrosion resistance of Mg-5Gd-3Y-0.8Zr alloy were investigated systematically. The corrosion rate of Mg-5Gd-3Y-0.8Zr alloy in NaCl solution was measured by static weight loss method. The results show that the as-cast alloys mainly consist of matrix α-Mg and cubic β phase (Mg_5Gd, Mg_ (24) Y_5). The amount of eutectic β phase distributed in the grain boundary obviously increases after aging treatment. After 12 h of corrosion, the corrosion rate of magnesium alloy increased obviously. After being eroded for 24 h in 3.5% NaCl (mass fraction) solution, the magnesium alloy was seriously corroded and the surface was covered with corrosion pits and non-shed white corrosion products. Easy to produce intergranular corrosion, cubic eutectic β-phase particles can effectively prevent the surface corrosion along the grain boundary to the magnesium alloy internal expansion, thereby enhancing the corrosion resistance of magnesium alloys.