等通道转角挤压加工路径对纯铜晶粒细化的影响（英文）

Effect of processing route on grain refinement in pure copper processed by equal channel angular extrusion

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。

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.