Dong Jinfang, Dong Qing, Dai Yongbing, Xing Hui, Han Yanfeng, Ma Jianbo, Zhang Jiao, Wang Jun, Sun Baode
Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai Jiao Tong University, Shanghai 200240, China.
Materials (Basel). 2017 Jan 22;10(1):87. doi: 10.3390/ma10010087.
Aluminum single crystal with 99.999% purity was deformed at room temperature by equal channel angular pressing (ECAP) up to 16 passes. Grain size and misorientation of processed samples were quantitatively characterized by TEM and EBSD. The results show that the refinement efficiency of high purity aluminum single crystal was poor in the initial stage. Extrusion by fewer ECAP passes ( ≤ 8) resulted in only elongated grains containing a large number of subgrains and small misorientations between grains. Stable microstructures of nearly equiaxed grains with high misorientations were obtained by 15 passages, indicating that the initial extremely coarse grains and highly uniform grain orientation are not conducive to the accumulation of strain energy. The initial state of high purity aluminum has a significant effect on the refining efficiency of the ECAP process.
纯度为99.999%的铝单晶在室温下通过等通道转角挤压（ECAP）进行变形，挤压次数高达16次。通过透射电子显微镜（TEM）和电子背散射衍射（EBSD）对加工样品的晶粒尺寸和取向差进行了定量表征。结果表明，高纯铝单晶在初始阶段的细化效率较差。较少的ECAP挤压次数（≤8次）挤压仅导致晶粒拉长，包含大量亚晶粒，且晶粒间取向差较小。通过15次挤压获得了具有高取向差的近等轴晶粒的稳定微观结构，这表明初始极粗大晶粒和高度均匀的晶粒取向不利于应变能的积累。高纯铝的初始状态对ECAP工艺的细化效率有显著影响。
