The interaction and migration of deformation twin in an eutectic high-entropy alloy AlCoCrFeNi2.1

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 degrees C. The microstructure reveals the intersection of twin-twin 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 Pi were formed by the edge dislocation 11 (2) over bar and the mixed dislocation 21 (1) over bar 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 degrees and 700 degrees 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. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.