顯微組織和性能的影響
(南京航空航天大學 材料科學與技術學院，南京 211100)
摘 要: 采用光學顯微鏡、掃描電子顯微鏡和X射線衍射儀等研究復合添加Ba與富La稀土對Mg-6Zn-4Si合金顯微組織、力學性能和腐蝕性能的影響。結(jié)果表明：Ba與富La稀土的復合添加起到協(xié)同變質(zhì)Mg2Si的作用；當同時添加0.5% Ba和0.5%富La稀土時，變質(zhì)效果最好，初生Mg2Si變?yōu)榧毿〉亩噙呅螤睿骄叽鐬?0 μm，共晶Mg2Si呈短桿或顆粒狀彌散分布于基體中；此時，Mg-6Zn-4Si合金的室溫和高溫抗拉強度較基體合金分別提高45.7%和52.4%，伸長率分別提高64.3%和62.5%，腐蝕速率較變質(zhì)前降低71.8%，腐蝕電流密度減小為3.127×10−5 A/cm2，降幅達一個數(shù)量級。
關鍵字: Mg-6Zn-4Si合金；合金化；顯微組織；力學性能；腐蝕性能
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
