(1. 合肥工业大学 航空结构件成形制造与装备安徽省重点实验室，合肥 230009；
2. 合肥中南光电有限公司，合肥 231600；
3. 合肥工业大学 有色金属与加工技术国家地方联合工程研究中心，合肥 230009)
摘 要: 采用金属模熔铸工艺制备含0.2% Sc (质量分数)的Al-Zn-Mg-Cu-Sc-Zr合金，分别研究合金铸态下和4种均匀化热处理工艺下的组织转变与元素分布。结果表明：加入0.2%的钪有助于抑制枝晶偏析，消除非平衡共晶组织，得到晶粒尺寸为55~80 μm(占整体75%)的合金；铸态组织晶界处分布有大量T(AlZnMgCu)相，在465 ℃下保温24 h后，T相完全转化为S(Al2CuMg)相；温度提高到480 ℃后，随着时间延长至24 h，晶界处的S相消失，只有少量的杂质相(Al7Cu2Fe)残留；在经过双级均匀化处理后，平均晶粒尺寸减小到40 μm，合金内部析出大量弥散分布的尺寸约为40 nm的L12型Al3Sc相，与α(Al)基体保持完全共格，有效阻碍了晶粒的粗化。
关键字: Al-Zn-Mg-Cu-Sc-Zr合金；均匀化；相转变；Al3Sc
（1. Anhui Province Key Laboratory of Aerospace Structural Parts Forming Technology and Equipment, Hefei University of Technology, Hefei 230009, China;
2. Chinaland Solar Energy Co., Ltd., Hefei 231600, China;
3. National-Local Joint Engineering Research Center of Nonferrous Metals and Processing Technology, Hefei University of Technology, Hefei 230009, China）
Abstract:In this paper, the structure transformation and element distribution of Al-Zn-Mg-Cu-Zr alloy with 0.2% Sc(mass fraction) in different states were studied. The results show that the addition of 0.2% Sc can help suppress dendrite segregation and eliminate the non-equilibrium eutectic structure, then an alloy with a grain size of 55-80 μm (accounting for 75% of the total) is obtained. A large number of T(AlZnMgCu) phases are distributed at the grain boundaries of the as-cast structure. After being kept at 465 ℃ for 24 h, the T phase is completely transformed into S(Al2CuMg) phase. Holding at 465 ℃ for 24 h, the S phase disappears at the grain boundary and only a small amount of impurity phase (Al7Cu2Fe) remains. Through the two-stage homogenization treatment, the average grain size is reduced to 40 μm. A large amount of L12-type Al3Sc phases with the sizes of about 40 nm are dispersed inside the alloy, which are completely coherent with the α(Al) matrix and effectively hinder the coarsening of grains.
Key words: Al-Zn-Mg-Cu-Sc-Zr alloy; homogenization; phase transformation; Al3Sc
