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采用金相显微镜、X射线衍射仪、扫描电镜和失重腐蚀试验,研究了不同Ce加入量时AZ31镁合金的显微组织、相组成及其在3.5%NaCl溶液中浸泡后的表面腐蚀形貌及腐蚀速率。结果表明:AZ31镁合金的显微组织主要由α-Mg固溶体和β-Mg_(17)Al_(12)相组成;加入质量分数为1.0%Ce~3.5%Ce后,AZ31镁合金的组织主要为α-Mg固溶体和Al-Ce相。当Ce含量为1.0%时,Al-Ce相尺寸小、数量少且沿晶界分布;随Ce含量增加,Al-Ce相数量增加,且出现偏聚加重现象。当Ce含量≤1.4%时,随Ce含量的增加,AZ31镁合金浸泡腐蚀76 h后的失重腐蚀速率变化较小;但当Ce含量>1.4%时,随Ce含量增加,该合金腐蚀速率急剧增大,耐腐蚀性能下降。向AZ31镁合金中加入Ce,形成了Al-Ce相,抑制了β-Mg_(17)Al_(12)析出。添加1.0%Ce时,AZ31镁合金耐腐蚀性能达到最佳。
The microstructure and phase composition of AZ31 magnesium alloy with different Ce additions and its surface corrosion morphology after immersion in 3.5% NaCl solution were studied by using optical microscope, X-ray diffraction, scanning electron microscopy and weight loss corrosion test. Corrosion rate. The results show that the microstructure of AZ31 magnesium alloy is mainly composed of α-Mg solid solution and β-Mg 17 Al 12 phase. The microstructure of AZ31 magnesium alloy after adding 1.0% Ce ~ 3.5% Ce is α-Mg solid solution and Al-Ce phase. When the content of Ce is 1.0%, the size and the number of Al-Ce phase are small and distributed along the grain boundaries. With the increase of Ce content, the amount of Al-Ce phase increases and the phenomenon of segregation increases. When the content of Ce is less than 1.4%, the change of corrosion rate of AZ31 magnesium alloy after 76 h immersion is small with the increase of Ce content. However, when the Ce content is over 1.4%, the corrosion rate of AZ31 alloy steeply increases with the increase of Ce content Large, corrosion resistance decreases. Adding Ce into AZ31 magnesium alloy to form Al-Ce phase restrains the precipitation of β-Mg_ (17) Al_ (12). When adding 1.0% Ce, AZ31 magnesium alloy has the best corrosion resistance.