Formation, reverse transformation, and properties of epsilon-martensite phase in the CoCrFeMnNi high-entropy alloy under high-pressure

摘要

A CoCrFeMnNi high-entropy alloy (HEA) was compressed at 20 GPa and room temperature, 500 degrees C, and 800 degrees C, respectively. We examined the microstructure and reverse transformation of the hexagonal closepacked (hcp) phase and its influence on the properties of the HEA after compression. The hcp laths with a width of several nanometer formed after compressed at room temperature, and kept the Kurdjumov-Sachs oriental relationship with the face-center-cubic (fcc) phase. During annealing, partial hcp laths transformed reversely into the fcc-structured nano twins. The influence of the hcp phase on the hardness of the HEA was discussed. In addition, the in situ resistance measurement also proved the fcc-to-hcp transition. (C) 2018 Elsevier B.V. All rights reserved.