Microstructure evolution and mechanical property of pure copper after multi-axial compression were investigated.Microstructure

evolution with the number of compressions was examined by scanning electron microscopy.The microhardness variation and distribution were investigated by measuring the Vickers microhardness on the middle section.The results show that dislocation division is the main mechanism of grain refinement.The subgrain misorientation increases by dislocation absorption and rearrangement with the increase of dislocation density and the rotation of compression axis,which leads to the grain refinement gradually.The ultra-fine grains are obtained in the most regions after 12 compressions.The microhardness is improved obviously, while its distribution on the middle plane is ununiform due to the friction between the billet and anvils, higher at the centeral portion and lower at the circumambience.

研究了多轴压缩后纯铜的组织演变和性能。通过扫描电子显微镜观察了组织随压缩次数变化的情况;通过测量试样中间面上的显微硬度研究了硬度随压缩次数变化以及硬度分布的情况。试验结果表明:位错分割是主要的晶粒细化机制，随位错密度的增大以及压缩轴的旋转，低应变时产生的亚晶通过吸收位错以及位错重排取向差不断增大，晶粒不断细化，12次压缩后，绝大部分区域为超细晶组织；多次压缩后材料硬度明显提高，但由于摩擦的影响，压缩后中间面的硬度分布不均匀，中心部位硬度较高，周围硬度较低。