CoCrFeMnNi高熵合金单向拉伸的组织和取向演变

Microstructure and grain orientation evolution of CoCrFeMnNi high-entropy alloy during uniaxial tensile deformation

采用电子背散射衍射技术,研究了室温下CoCrFeMnNi高熵合金在单向拉伸（真应变量为0%~12.4%）过程中的组织和取向演变。结果表明,初始组织表现为等轴晶形貌,退火孪晶形成于等轴晶粒内;拉伸后,等轴晶粒被拉长,小角度晶界急剧增多且主要分布在细小孪晶界和大角度晶界附近。该合金通过位错滑移的方式协调其室温下的拉伸变形。在变形过程中,晶粒取向不均匀转动,但晶粒内基体和孪晶的取向大体上沿着相同的方向转动,基体拉伸轴的转动规律为,反极图〈112〉和〈111〉附近的基体拉伸轴向〈111〉方向转动,符合Taylor模型;反极图中心和〈101〉附近的基体拉伸轴向〈001〉-〈111〉连线转动,符合Sachs模型;反极图〈001〉附近的基体拉伸轴转动无明显规律。

The evolution of microstructure and grain orientation of CoCrFeMnNi high entropy alloy during tensile deformation were investigated using electron backscatter diffraction technology.The results show that the original microstructure exhibits equiaxed grain morphology and possesses annealing twinning in the equiaxed grain interior,while the tensile deformation makes equiaxed grains be elongated and results in quick formation of low angle grain boundaries mainly distributed around the twinning boundaries and high angle grain boundaries.During tensile deformation at room temperature which is coordinated through dislocation glide,the grain orientation rotations are inhomogeneous,but the matrix and twinning within individual grain rotate along approximately similar tendency.For matrices,the tensile axes close to〈112〉and〈111〉rotate toward〈111〉following Taylor model;the tensile axes close to 〈101〉 and close to middle in the stereographic triangle rotate to the line of 〈001〉-〈111〉following Sachs model;the tensile axes close to〈001〉 rotate without any significant regularities.