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通过高压扭转对Cu试样施加不同程度的变形,利用OM,TEM及差示扫描量热仪(DSC)对变形组织微观结构及其热稳定性进行了分析.在较小的变形程度下,变形组织为高位错密度的位错胞、亚晶组织,试样的变形储能随变形量的增大而增大,在切应变等于13时达到最大,为0.91 J/mol,DSC曲线显示的放热峰随变形量的增大向低温方向偏移;进一步变形,动态回复加剧,高位错密度的亚晶组织逐渐演化成无位错的等轴状晶粒组织,试样的变形储能减小,组织的稳定性提高.显微硬度随退火温度的提高而减小,晶粒的明显长大导致显微硬度急剧减小.出现明显晶粒长大的温度较DSC曲线显示的放热峰起始温度低45℃左右,这主要是由于变形组织的回复再结晶过程是退火温度与时间的函数,降低处理温度并延长处理时间能达到与高温短时处理相同的效果.
The microstructure and thermal stability of the deformed microstructure were analyzed by OM, TEM and differential scanning calorimetry (DSC) with different degrees of deformation of the Cu sample by high-pressure torsion. At a relatively small degree of deformation, deformation The dislocation energy storage of the dislocation cells, subgrain and microstructure with high dislocation density increased with the increase of the deformation, reached the maximum at shear strain equal to 13, which was 0.91 J / mol. The DSC curve showed that The thermal peak shifts to the low temperature with the increase of the deformation amount. Further deformation and dynamic recovery aggravate. The high dislocation density subgrain gradually evolves into dislocation-free equiaxed grain structure, and the deformation energy storage of the sample decreases , The stability of the microstructure increased.The microhardness decreased with the increase of annealing temperature, the obvious increase of the grain size led to the sharp decrease of the microhardness.The apparent temperature of the grain growth was more pronounced than that of the DSC curve The initial temperature is about 45 ℃ lower, which is mainly due to the recovery of the deformed structure. The recrystallization process is a function of annealing temperature and time. Reducing the treatment temperature and prolonging the treatment time can achieve the same effect as the short treatment with high temperature.