显微组织和性能的影响
(南京航空航天大学 材料科学与技术学院，南京 211100)
摘 要: 采用光学显微镜、扫描电子显微镜和X射线衍射仪等研究复合添加Ba与富La稀土对Mg-6Zn-4Si合金显微组织、力学性能和腐蚀性能的影响。结果表明：Ba与富La稀土的复合添加起到协同变质Mg2Si的作用；当同时添加0.5% Ba和0.5%富La稀土时，变质效果最好，初生Mg2Si变为细小的多边形状，平均尺寸为20 μm，共晶Mg2Si呈短杆或颗粒状弥散分布于基体中；此时，Mg-6Zn-4Si合金的室温和高温抗拉强度较基体合金分别提高45.7%和52.4%，伸长率分别提高64.3%和62.5%，腐蚀速率较变质前降低71.8%，腐蚀电流密度减小为3.127×10−5 A/cm2，降幅达一个数量级。
关键字: Mg-6Zn-4Si合金；合金化；显微组织；力学性能；腐蚀性能
microstructure and properties of Mg alloy
（College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China）
Abstract:The effect of combinative addition of Ba and La-rich rare earth on the microstructure, mechanical properties and corrosion properties of Mg-6Zn-4Si alloy was investigated by optical microscopy, scan electron microscopy and X-ray diffractometry. The results indicate that addition of Ba and La-rich rare earth has combinative modification effect on Mg2Si. When adding 0.5% Ba and 0.5% La-rich RE, the combinative effect is the best. The primary Mg2Si changes into fine polygonal particles with the average size of about 20 μm. The eutectic Mg2Si changes into short bars or small particles. The mechanical properties and corrosion resistance of the Mg-6Zn-4Si alloy with 0.5%Ba and 0.5% La-rich RE are the best. The room and high temperature tensile strength are increased by 45.7% and 52.4%, respectively. The elongation is increased by 64.3% and 62.5%. The corrosion rate is 71.8%, which is lower than that of the base alloy. The corrosion current density is 3.127×10−5 A/cm2, which is reduced nearly an order.
Key words: Mg-6Zn-4Si alloy; alloying; microstructure; mechanical properties; corrosion properties
