镁合金表面锌合金化层组织及性能研究.pdfVIP

学兔兔 Mar．2011 VOI．6O No．3 ·233 · 镁合金表面锌合金化层组织及性能研究 张 雄，董选普，陈东风，樊自田 (华中科技大学材料成形与模具技术国家重点实验室，湖北武汉430074) 摘要：采用消失模铸造方法在镁合金表面制备了一层锌合金『匕层，并对合金化层进行了光学显微分析、扫描电镜分 析、能谱分析、x射线衍射及腐蚀性能分析。研究结果表明：当充型到合金化涂料层表面的镁合金液体温度较低时， 镁合金表面锌合金化层才能形成；合金化层的组成物相为Mg 7Al。 、Al Mg Zn4、Zn、Mg；合金化过程中锌一方面可以 参与合金化反应形成蜂窝状物质A1 g．．Zn ，男一方面可以诱导镁合金表面形戎Mg A1 ：和 —MgN．成的共晶组织；经合 金化后的镁合金自腐蚀电位升高，自惰蚀电流下降，耐蚀性能上升 关键词：镁合金；表面锌合金化；消失模铸造；腐蚀 中图分类号：TG174．445；TG146．2+2 文献标识码：A 文章编号：1001—4977(201 1)03—0233—05 Microstructure and Properties of Zinc—Alloying Layer on Magnesium Alloy Surface ZHANG Xiong，DONG Xuan—pu，CHEN Dong—feng，FAN Zi—tian (State Key Laboratory of Material Processing and DieMould Technology，Huazhong University of Science and Technology，Wuhan 430074，Hubei，China) Abstract：The zinc—alloying layer was fabricated on magnesium alloy SUrface by Iost foam casting． Optical microscope，scanning electron microscope，energy dispersive spectrometer and X—ray di仟raction were used to analyze the micrOstructure and composition of the layer whose corrosion property was also tested．The results show that only when the temperature of the liquid magnesium alloy reaching the SUrface of the alloying coating iS IOW．can the Zn—alloying layer fOrm．The surface alloying layer mainly consists of Mg17AI12，AIsMg11Zn4，Zn and Mg phases．Zinc can not only participate in the alloying reaction and fOrming the honeycomb phase AI5Mg11Zn4，but also can induce the forming of eutectic structure which iS composed of Mg17Al12 and 0c—Mg．The corrosion potential of the Surface alloyed magnesium iS enhanced and the corrosion current iS declined．which indicates that the corrosion resistance is improved． Key words：magnesium a