(1. 广东工业大学 机电工程学院,广州 510006;
2. 广东省特种设备检测研究院,中山 528400;
3. 中南大学 材料科学与工程学院,长沙 410083;
4. 中南大学 有色金属材料科学与工程教育部重点实验室,长沙 410083)
摘 要: 针对经过90°模具、8道次等通道转角挤压的纯铜,采用电子背散射电子衍射(EBSD)和透射电镜(TEM)分析大范围内加工路径对其显微组织演变的影响。每个路径按照道次间棒料绕其长轴转动角度(χ)进行定义,角度变化范围为0°~180°。EBSD所测大角度晶界比例和晶粒大小结果表明,当χ=90°时晶粒细化效率最高,χ=180°时晶粒细化效率最低。该趋势得到TEM结果的进一步佐证。对比EBSD和TEM结果还发现,在定量比较ECAE材料的显微组织差异时,应该充分考虑晶粒组织形貌的非等轴特征。
关键字: 纯铜;等通道转角挤压;剧烈塑性变形;应变路径;晶粒细化
(1. School of Electro-Mechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;
2. Guangdong Institute of Special Equipment Inspection and Research, Zhongshan 528400, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
4. Key Laboratory of Nonferrous Metal Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China)
Abstract:An experimental study of the microstructures in pure copper billets processed by 8 passes of equal channel angular extrusion (ECAE) via an extended range of processing routes with a 90° die is carried out. Each processing route is defined according to the inter-pass billet rotation angle (χ), which varies from 0° to 180°. According to the generation of high-angle boundaries and reduction of grain size by electron backscatter diffraction (EBSD) measurements, the grain refinement is found to be most efficient for route with χ=90° and least efficient with χ=180°, among the seven routes studied. This trend is supported by supplementary transmission electron microscopy (TEM) measurements. Comparison of the EBSD and TEM data reveals the importance of considering the non-equiaxity of grain structures in quantitative assessment of microstructural differences in ECAE-processed materials.
Key words: pure copper; equal channel angular extrusion; severe plastic deformation; strain path; grain refinement