鑄態(tài)及其均勻化組織
(1. 中南大學 材料科學與工程學院，長沙 410083；
2. 中南大學 有色金屬材料科學與工程教育部重點實驗室，長沙 410083)
摘 要: 采用光學顯微鏡(OM)、X射線衍射(XRD)、差示掃描量熱儀(DSC)和掃描電鏡(SEM)及其附件能譜儀(EDX)研究Al-(7.8~9.0)Zn-1.6Mg-(1.0~2.2)Cu鋁合金的鑄態(tài)及其均勻化組織。結(jié)果表明： 該鋁合金的鑄態(tài)凝固組織由α(Al)基體+Mg(Zn, Al, Cu)2非平衡共晶相組成；鑄態(tài)組織中粗大非平衡共晶組織的體積分數(shù)隨著Zn含量的增加而增大，且伴隨其周圍析出的條狀、細小Mg(Zn, Al, Cu)2粒子也逐漸增多、粗化；當Cu含量(質(zhì)量分數(shù))為1.0%、1.4%、2.2%時，鑄態(tài)組織晶內(nèi)的獨立第二相分別為T(Al2Zn3Mg3)相、S(Al2CuMg)相、T(Al2Zn3Mg3)相+θ(Al2Cu)相；各成分合金經(jīng)過(470 ℃, 24h)均勻化處理時，基體中僅剩下均勻化過程無法消除的尺寸較小、數(shù)量較少的初生富Fe相。
關鍵字: Al-Zn-Mg-Cu合金；鑄態(tài)；均勻化；微結(jié)構(gòu)
Al-(7.8-9.0)Zn-1.6Mg-(1.0-2.2)Cu aluminum alloys
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China）
Abstract:The microstructures of the as-cast and homogenized Al-(7.8-9.0)Zn-1.6Mg-(1.0-2.2)Cu aluminum alloys were studied by OM, XRD, DSC, SEM and EDX techniques. The results show that the as-cast microstructure of Al-(7.8-9.0)Zn-1.6Mg-(1.0-2.2)Cu aluminum alloy mainly consists of Mg(Zn, Al, Cu)2 phase and α(Al) matrix. The volume fraction of coarse eutectic-structure increases with Zn content increasing. Meanwhile, the accompanying precipitations of small Mg(Zn, Al, Cu)2 particles are also gradually increased. When Cu content(mass fraction) is 1.0%, 1.4% and 2.2% , the main second phases within grains are T(Al2Zn3Mg3) phase, S(Al2CuMg) phase and T(Al2Zn3Mg3)+ θ(Al2Cu) phases, respectively. The only remained particles in the matrix are some small Fe-rich particles after being homogenized at 470 ℃ for 24 h.
Key words: Al-Zn-Mg-Cu alloy; as cast; homogenization; microstructure
