摘要
目前,关于Mn对AZ91铸态镁合金耐蚀性能影响的研究并不充分,尤其是腐蚀机制方面仍不清楚。采用静态失重、电化学及盐雾腐蚀法研究了Mn含量对AZ91铸态镁合金微观组织及耐腐蚀性能的影响。利用金相显微镜(OM)、扫描电镜(SEM)观察AZ91铸态镁合金的微观组织和腐蚀形貌,采用能谱(EDS)仪、X射线衍射仪(XRD)分析了其物相组成。结果表明:AZ91铸态镁合金中的Mn主要以颗粒状的低电化学活性物质Al2Mn形式存在,阻碍了其腐蚀过程的进行;Mn能使AZ91铸态镁合金中的有效腐蚀相β-Mg17Al12减少,分布更弥散,从而使合金的腐蚀电位升高,腐蚀电流降低,腐蚀速率降低,耐腐蚀性能增强;含0.8%Mn的铸态镁合金的耐腐蚀性能最好。
The effects of Mn content on the microstructure and corrosion resistance of as-cast AZ91 magnesium alloys were investigated by static weight loss method,electrochemical method and salt spray test.The microstructure and corroded surface morphology of the alloys were observed with an optical microscope and a scanning electronic microscope.The composition of the alloys was analyzed by energy dispersive spectroscopy and X- ray diffraction.Results showed that most Mn in as- cast AZ91 magnesium alloy existed in the state of granular Al_2 Mn phase which had lower electrochemical activity and could hinder the corrosion process of the Mg alloy.In the meantime,Mn was able to effectively reduce the content of β-Mg_(17)Al_(12) phase that was liable to corrosion in the Mg alloy and enhance its dispersive distribution thereby increasing the corrosion potential,reducing the corrosion current and corrosion rate,and improving the corrosion resistance.As-cast AZ91 Mg alloy containing 0.8%Mn exhibited the best corrosion resistance.
出处
《材料保护》
CAS
CSCD
北大核心
2014年第7期52-56,8,共5页
Materials Protection
基金
山西省专利推广实施资助项目(121004)
