热处理工艺对Mg-Gd-Y合金组织及耐腐蚀性能的影响  

Effect of heat treatment process on microstructure and corrosion resistance of Mg-Gd-Y alloy

作　　者：焦迪 王萍[1] JIAO Di;WANG Ping(School of Materials and Chemical Engineering,Xi’an Technological University,Xi’an 710021,China)

机构地区：[1]西安工业大学材料与化工学院,陕西西安710021

出　　处：《材料热处理学报》2020年第9期59-66,共8页Transactions of Materials and Heat Treatment

基　　金：陕西高校“金属腐蚀防护与表面工程技术”青年创新团队,陕西省重点研发计划项目(2018GY-111);陕西省教育厅产业化培育项目(17JF009);榆林科技计划项目(2018-2-30)。

摘　　要：研究了Mg-Gd-Y合金铸态、固溶态及时效态的组织及耐腐蚀性能。采用扫描电镜(SEM)、能谱仪(EDS)等对镁合金腐蚀前后的组织结构及腐蚀过程进行了分析表征,并通过浸泡实验及电化学工作站对镁合金的腐蚀速率及腐蚀行为进行了研究。结果表明:Mg-Gd-Y合金在3.5%NaCl溶液中腐蚀优先发生在Zr相周围,然后沿晶界的Mg-RE周围向着基体不断扩展,并且基体内部出现明显的点蚀。铸态镁合金沿晶界处存在大量共晶组织镁-稀土相。固溶处理使共晶组织和第二相粒子大部分溶入晶粒内,组织趋于均匀,耐腐蚀性能提高;时效处理后合金晶界处生成了一些小颗粒状的析出相,耐腐蚀性能较固溶态有所下降。电化学测试结果表明,铸态镁合金自腐蚀电位较低,固溶态和时效态镁合金自腐蚀电位正移。3种状态镁合金都发生了点蚀,腐蚀产物膜缺陷较多,对基体保护作用较小。Corrosion resistance of Mg-Gd-Y alloy in as-cast,solid solution treated and aged states were studied,microstructure and corrosion process of the magnesium alloy before and after corrosion were analyzed and characterized by means of scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS)analysis,and the corrosion rate and corrosion behavior of the magnesium alloy were studied by immersion experiment and electrochemical workstation.The results show that the corrosion of the Mg-Gd-Y alloy in 3.5%NaCl solution occurs preferentially around the Zr phase,and then continuously expands towards the matrix around the Mg-RE along the grain boundary,and there is obvious pitting corrosion inside the matrix.There are a large number of eutectic structure magnesium-rare earth phases in the grain boundary of the as-cast magnesium alloys.The solid solution treatment causes most of the eutectic structure and the second phase particles to dissolve into the grain,and the microstructure tends to be uniform,and the corrosion resistance of the alloy is improved.After aging treatment,some small granular precipitates are formed at the grain boundaries of the alloy,and the corrosion resistance is lower than that of the after solid solution treatment.The results of electrochemical tests show that the self-corrosion potential of the as-cast magnesium alloy is low,and the self-corrosion potential of the solid solution treated and aged magnesium alloy is positive shift.Pitting corrosion occurs in the three states of the magnesium alloy,and the defects of corrosion products film are more,which has little effect on matrix protection.

关 键 词：MG-GD-Y合金 热处理 耐腐蚀性能 电化学测试 

分 类 号：TG146.2[一般工业技术—材料科学与工程]