【摘要】 通过高压扭转(HPT)技术在不同转速条件下实现了Cu试样的晶粒细化。利用光学显微镜(OM)、透射电镜(TEM)及显微硬度计观察并测试了组织的结构与性能,并基于有限元计算了变形诱导试样的温升,研究了转速对Cu试样的组织细化与性能的影响。结果表明:转速由1/3r.min-1增大至1r.min-1,经1圈扭转变形,试样温度由40.8℃升高到54.1℃,变形组织均为100～600nm的高位错密度位错胞/亚晶组织,显微硬度由初始态的52HV0.05增大至140HV0.05;经16圈扭转变形,试样温度由50.4℃升高到97.4℃,组织细化到200nm。慢速扭转变形试样晶内位错密度高,微观组织处于严重变形状态;而快速扭转试样晶内衬度均匀,位错较少,微观组织经历明显的动态回复,显微硬度较慢速扭转变形试样低6%。更多还原

【Abstract】 Cu specimens were deformed by high-pressure torsion(HPT)at different revolution speeds,to investigate the effect of revolution speed on its microstructure and mechanical properties by means of OM,TEM and microhardness testing.It was found that heavily deformed microstructure with average grain size in 200 nm formed in the sample after HPT deforming to large strains at a revolution speed of 1 /3 r.min-1.Increasing revolution speed up to 1 r.min-1,some dislocation-free fine grains appears,leading to a 6 percent of decrease in average hardness as compared to the lower revolution speed counterparts.One turn of HPT deformation induces dislocation-cells /subgrains with size in 100—600 nm formed and an increase in hardness from 52 to 140 HV0.05.The evolution of the microstructure and mechanical properties with revolution speed was interpreted by using a thermal analysis simulation based on heat generation induced by the extensive HPT deformation.更多还原