(1. 合肥工業(yè)大學(xué) 航空結(jié)構(gòu)件成形制造與裝備安徽省重點實驗室，合肥 230009；
2. 合肥中南光電有限公司，合肥 231600；
3. 合肥工業(yè)大學(xué) 有色金屬與加工技術(shù)國家地方聯(lián)合工程研究中心，合肥 230009)
摘 要: 采用金屬模熔鑄工藝制備含0.2% Sc (質(zhì)量分?jǐn)?shù))的Al-Zn-Mg-Cu-Sc-Zr合金，分別研究合金鑄態(tài)下和4種均勻化熱處理工藝下的組織轉(zhuǎn)變與元素分布。結(jié)果表明：加入0.2%的鈧有助于抑制枝晶偏析，消除非平衡共晶組織，得到晶粒尺寸為55~80 μm(占整體75%)的合金；鑄態(tài)組織晶界處分布有大量T(AlZnMgCu)相，在465 ℃下保溫24 h后，T相完全轉(zhuǎn)化為S(Al2CuMg)相；溫度提高到480 ℃后，隨著時間延長至24 h，晶界處的S相消失，只有少量的雜質(zhì)相(Al7Cu2Fe)殘留；在經(jīng)過雙級均勻化處理后，平均晶粒尺寸減小到40 μm，合金內(nèi)部析出大量彌散分布的尺寸約為40 nm的L12型Al3Sc相，與α(Al)基體保持完全共格，有效阻礙了晶粒的粗化。
關(guān)鍵字: Al-Zn-Mg-Cu-Sc-Zr合金；均勻化；相轉(zhuǎn)變；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
