Anomalous strengthening in a low-temperature aged FeMnCoCrN high-entropy alloy: Role of local chemical order

As an intrinsic microstructural feature of medium-and high-entropy alloys (M/HEAs), local chemical order (LCO) shows a great potential in regulating mechanical properties of those materials. In this study, LCO domains ranging in size from sub-nanometer to several nanometers were obtained in FeMnCoCrN HEA by long-term low-temperature aging, achieving a simultaneous improvement of tensile strength and ductility. The significant strengthening induced by LCO domains can compensate for the loss in strength caused by recovery, leading to an impressive strengthening of the alloy. Moreover, the non-uniform distribution of LCO domains provides an additional hardening induced by heterogeneous deformation, enhancing the work hardening ability and uniform deformation. These findings reveal the quantitative impact of LCO on the mechanical property of M/HEAs, which provides valuable insights for the design and development of high-performance metallic materials.