(1. 華南理工大學(xué) 材料科學(xué)與工程學(xué)院，廣州 510640；2. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082)
摘 要: 利用光學(xué)顯微鏡、顯微硬度計、X射線衍射儀、掃描電鏡和透射電鏡分析時效熱處理(T6)后的Mg-3Zn-1.5Cu-0.6Zr鎂合金的析出相。結(jié)果表明：合金鑄態(tài)組織主要由初晶Mg基體和非平衡共晶組織(Mg+Mg2Cu，CuMgZn)組成；經(jīng)固溶處理，晶界處大部分非平衡共晶組織溶解。經(jīng)180 ℃，16 h時效后，合金達(dá)到時效硬度峰值，此時晶內(nèi)析出相主要有3類：1) 少量棒狀的過渡相β1′-α(可能是Mg4Zn7)，其軸線垂直于(0001)Mg，長度大約50 nm；2) 大量彌散分布的板條狀和棱柱狀的β2′-MgZn2，其軸線垂直于(0001)Mg，長度為50~150 nm，該相是合金的主要時效硬化相；3) 少量短桿狀的β-MgZn，其軸線平行于(0001)Mg，長度約20 nm。
關(guān)鍵字: 鎂合金；Mg-Zn-Cu鎂合金；MgZn2；MgZn；顯微組織；時效硬化
as-cast Mg-3Zn-1.5Cu-0.6Zr Mg alloy
（1.School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China;
2.School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The morphologies of the precipitates formed in an aged Mg-3Zn-1.5Cu-0.6Zr alloy were analyzed with optical microscope, microhardness tester, X-ray diffractometry(XRD), scanning electron microscope(SEM) and transmission electron microscope (TEM). The results show that the microstructure of the as-cast alloy is composed of the Mg matrix and nonequilibrium eutectic (Mg+Mg2Cu,CuMgZn) formed at the grain boundaries, and a majority of the nonequilibrium eutectics are dissolved after solution treatment. There are mainly three types of precipitates of alloy after aging at 180 ℃ for 16 h. The first one is a small amount of rod-like β1′-a(possibly Mg4Zn7), which has an average length of about 50 nm and is perpendicular to the base plane (0001)Mg of the Mg matrix. The second type of precipitate is a lath-like or prismatic β2′-MgZn2 with high-density and length of 50−150 nm, which is also perpendicular to the base plane of the Mg matrix and serves as the principal hardening phase of the aged alloy. The third precipitate is the short-rod like equilibrium β-MgZn, also in a small amount, with average length of about 20 nm and its axis is parallel to the base plane of the Mg matrix.
Key words: Mg alloy; Mg-Zn-Cu Mg alloy; MgZn2; MgZn; microstructure; age-hardening
