(1. 湖南工业大学 冶金与材料工程学院，株洲 412007；
2. 湘潭大学 材料科学与工程学院，湘潭 411105;
3. 安徽建业科技有限公司，淮北 235000)
摘 要: 采用高分辨透射电镜(TEM)、X射线衍射仪(XRD)、能谱仪(EDS)和硬度测试等手段，研究快速冷冲强变形过程中喷射成形细晶Al-Cu-Mg合金长片状S''''相的演变规律。结果表明：挤压态Al-Cu-Mg合金在快速冷冲强变形过程中长片状S''''相发生扭曲、脆断、回溶和缩颈，长片状S''''相的形貌、尺寸、分布及与基体的取向关系发生显著变化，从有规律分布的长片状纳米析出相演变为无规律分布的短棒状S''''相和弥散分布的颗粒状再析出相。长片状S''''相的扭曲和脆断，显著增大析出相与铝基体的接触面，提高了析出相与铝基体的界面畸变能，促进了S''''相的回溶，导致铝基体重新达到过饱和状态，从而发生再析出以降低基体自由能。挤压态Al-Cu-Mg合金在快速冷冲过程中合金硬度显著增加，由53HB增加到127HB，升高139.6%。
关键字: Al-Cu-Mg合金；快速冷冲；S''相；破断；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
