(1. 湖南工業(yè)大學 冶金與材料工程學院，株洲 412007；
2. 湘潭大學 材料科學與工程學院，湘潭 411105;
3. 安徽建業(yè)科技有限公司，淮北 235000)
摘 要: 采用高分辨透射電鏡(TEM)、X射線衍射儀(XRD)、能譜儀(EDS)和硬度測試等手段，研究快速冷沖強變形過程中噴射成形細晶Al-Cu-Mg合金長片狀S''''相的演變規(guī)律。結果表明：擠壓態(tài)Al-Cu-Mg合金在快速冷沖強變形過程中長片狀S''''相發(fā)生扭曲、脆斷、回溶和縮頸，長片狀S''''相的形貌、尺寸、分布及與基體的取向關系發(fā)生顯著變化，從有規(guī)律分布的長片狀納米析出相演變?yōu)闊o規(guī)律分布的短棒狀S''''相和彌散分布的顆粒狀再析出相。長片狀S''''相的扭曲和脆斷，顯著增大析出相與鋁基體的接觸面，提高了析出相與鋁基體的界面畸變能，促進了S''''相的回溶，導致鋁基體重新達到過飽和狀態(tài)，從而發(fā)生再析出以降低基體自由能。擠壓態(tài)Al-Cu-Mg合金在快速冷沖過程中合金硬度顯著增加，由53HB增加到127HB，升高139.6%。
關鍵字: Al-Cu-Mg合金；快速冷沖；S''相；破斷；回溶
（1. College of Metallurgy and Material Engineering, Hunan University of Technology, Zhuzhou 421007, China;
2. School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China;
3. Anhui Jianye Science and Technology Co., Ltd., Huaibei 235000, China）
Abstract:The high resolution transmission electron microscopy (TEM), X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS) and hardness test were used to study the evolution of long strip-shaped S'''' phase of the spray-formed fine-grained Al-Cu-Mg alloy during rapid cold-stamping deformation. The results show that the elongated S'''' phase of the extruded Al-Cu-Mg alloy is distorted, brittle fracture, re-dissolution and necking during the rapid cold-stamping deformation, and the morphology, size, distribution and the orientation relationship with the matrix of the long strip-shaped S'''' phase changes significantly. The regularly distributed long strip-shaped nano-scale precipitates evolve into irregularly distributed short rod-shaped S'''' phases and diffusely distributed granular re-precipitates. The twist and brittle fracture of the long strip S'''' phase significantly increases the contact surface between the precipitated phase and the aluminum matrix, improves the interfacial distortion energy of the precipitated phase and the aluminum matrix, and promotes the re-dissolution of the S'''' phase. The supersaturation state is reached, so that re-precipitation occurs to lower the matrix free energy. The hardness of the alloy in the extruded Al-Cu-Mg alloy increases from 53 HB to 127 HB during the rapid cold stamping process.
Key words: Al-Cu-Mg alloy; rapid cold-stamping; S'' phase; fracture; re-dissolution
