等通道转角挤压加工路径对纯铜晶粒细化的影响

摘要

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.%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。