(1. 中南大學(xué) 輕合金研究院，長沙 410083；
2. 中南大學(xué) 輕質(zhì)高強(qiáng)結(jié)構(gòu)材料重點(diǎn)實(shí)驗室，長沙 410083；
3. 中南大學(xué) 有色金屬先進(jìn)結(jié)構(gòu)材料與制造協(xié)同創(chuàng)新中心，長沙 410083)
摘 要: 利用Thermo-cale軟件計算及OM、SEM、XRD、DTA等分析手段，對比研究幾種高Zn型超強(qiáng)Al-Zn-Mg-Cu系合金的鑄態(tài)與均勻化態(tài)組織。結(jié)果表明：高Zn低Cu含量的7037、7056、7097鋁合金鑄態(tài)組織中主要存在a(Al)+Mg(Zn,Cu,Al)2共晶組織，經(jīng)多級均勻化熱處理后非平衡結(jié)晶相基本溶解；高Zn高Cu含量的7095鋁合金沿晶界呈網(wǎng)狀分布的粗大凝固組織主要由a(Al)、Mg(Zn,Cu,Al)2相、T(AlZnMgCu)相以及少量的θ(Al2Cu)相組成，經(jīng)均勻化熱處理后，僅存在少量AlZnMgCu相；高Zn低Cu含量合金凝固及均勻化組織中非平衡結(jié)晶相少的主要原因是合金成分遠(yuǎn)離極限固溶度曲線。
關(guān)鍵字: Al-Zn-Mg-Cu系合金；相圖計算；鑄態(tài)組織；均勻化
（1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. Science and Technology on High Strength Structural Materials Laboratory, Central South University, Changsha 410083, China;
3. Collaborative Innovation Center of Advanced Nonferrous Structural Materials and Manufacturing, Central South University, Changsha 410083, China）
Abstract:The microstructure in as-cast and homogenized Al-Zn-Mg-Cu alloys with high Zn ultra-high strength were investigated by thermo-cale software, OM, SEM, XRD, DTA. The results indicate that the as-cast microstructure of alloys 7037, 7056 and 7097 with high Zn low Cu content, in which eutectic microstructure mainly contains a(Al) and Mg(Zn,Cu,Al)2 after multi-homogenizing, the non-equilibrium crystalline phases are almost dissolved. The coarse solidification microstructure along the grain boundaries of 7095 alloy with high Zn, Cu contents is composed of a(Al), Mg(Zn,Cu,Al)2 phase, T(AlZnMgCu) phase and a small amount of θ(Al2Cu) phase, only some of AlZnMgCu phases still remains in matrix after being homogenized. The main reason for less non-equilibrium crystalline phases in aluminum alloys with high Zn low Cu content is that the composition of alloys is far from the limit of solubility curves.
Key words: Al-Zn-Mg-Cu alloys; thermodynamic calculation; as-cast microstructure; homogenization
