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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。
The effects of trace Er on the microstructure and corrosion properties of as-cast ZM5 magnesium alloy were studied by metallographic microscope, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, weight loss and potentiodynamic scanning. The results show that the trace Er can refine the as-cast microstructure of ZM5 magnesium alloy and improve the corrosion resistance. In the range of 0 ~ 0.6%, the Mg17Al12 phase in the alloy gradually changes from coarse to continuous dendritic to Fine, dispersed particles evenly distributed; when the Er content of 0.6%, the organization Al3Er phase generated. With the increase of Er content, the average corrosion rate of ZM5 magnesium alloy decreases gradually. When Er content is 0.6%, the corrosion rate of immersion in 3.5% NaCl aqueous solution is 2.125 6 mg / (cm2.d) 20% of conventional ZM5 magnesium alloy. Trace Er makes ZM5 magnesium alloy 3.5% NaCl solution in the corrosion potential increases, the self-corrosion current decreases.