The interaction and migration of deformation twin in an eutectic high-entropy alloy AlCoCrFeNi_2.1

Yaoli Zhang^1,2，Jinguo Li^1,3，Xinguang Wang¹，Yiping Lu⁴，Yizhou Zhou¹，Xiaofeng Sun¹

1. Institute of Metal Research, Chinese Academy of Sciences2. School of Materials Science and Engineering, University of Science and Technology of China3. Key Laboratory of Space Manufacturing Technology, Chinese Academy of Sciences4. School of Materials Science and Engineering, Dalian University of Technology

摘 要：An eutectic high-entropy alloy consisting Al, Co, Cr, Fe and Ni elements was prepared by vacuum directional solidification technology. The alloy exhibits excellent comprehensive mechanical performance during tension at temperature range of 600–700℃. The microstructure reveals the intersection of twintwin is the prevailing deformation mechanism and the twins play a dual role in strengthening and toughening the alloy in the thermomechanical process. The deformation twin variants I and were formed by the edge dislocation 11 2 and the mixed dislocation 21 1 on the {111} crystal planes, respectively. Besides, the dislocation jogs and kinks caused by twin intersection on the slip planes can strengthen the alloy, which may contribute to the high strength（the tensile strengths at the 600°and 700°tensile tests are respectively780 MPa and 630 MPa.）. Moreover, the coherent twin boundary migration has the function of coordinating deformation and contributes to the high ductility of the alloy.

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