微量Er对ZM5镁合金微观组织及腐蚀性能的影响

利用金相显微镜、扫描电镜、能谱分析、X射线衍射分析、失重法及动电位扫描测试法,研究了微量Er对铸态ZM5镁合金显微组织和腐蚀性能的影响.结果表明微量Er可细化ZM5镁合金的铸态组织,提高耐腐蚀性能；在0～0.6％范围内,随着Er含量的增加,合金中的Mg17Al12相由粗大、连续树枝状分布逐渐转变为细小、弥散的颗粒状均匀分布；当Er含量为0.6％时,组织中有Al3Er相生成.随着Er添加量的逐渐增加,ZM5镁合金的平均腐蚀速率逐渐降低；当Er含量为0.6％时,在3.5％NaCl水溶液中浸泡的腐蚀速率为2.125 6 mg/(cm2·d),仅为常规ZM5镁合金的20％.微量Er使得ZM5镁合金在3.5％ NaCl溶液中的自腐蚀电位升高,自腐蚀电流降低.

Influence of Er Addition on Microstructure and Corrosion Resistance of ZM5 Magnesium Alloy

The effects of tiny Er on microstructure and corrosion behavior of ZM5 magnesium alloy were examined by OM,SEM,EDS,XRD,weight loss method and polarization curve measurement.The result shows that the microstructure of ZM5 magnesium with trace addition of Er refines and its corrosion resistance improves.As the addition quantity of Er increasing in the range of 0%~0.6%,the Mg17Al12 phrase in the alloy can be refined and its morphology turns from thick dendrimer to disperse grain.A new phrase of Al3Er is found in the alloy with 0.6% Er addition.The average corrosion rate of ZM5 alloy decreases accordingly with the increase of the addition of Er.The alloy with 0.6% Er addition has the best corrosion resistance,and the corrosion rate is 2.125 6 mg/(cm2·d),only 20% of common ZM5 magnesium alloy.With trace addition of Er,the corrosion potential of the alloys increases,while the corrosion current of the alloys decreases.