Low-temperature annealing induces superior shock-resistant performance in FeCoCrNiCu high-entropy alloy

Abstract

By virtue of ultrahigh hardness, excellent wear resistance, and superior thermal stability, FeCoCrNiCu high-entropy alloys (HEAs) have promise for a wide range of structural applications. However, the focus of existing studies has been on quasi-static or static conditions, while a fundamental understanding is still limited to the mechanical response and deformation behavior under dynamic loading. Here, the dynamic compression test was carried out to explore the dynamic response mechanism of the FeCoCrNiCu HEA in terms of annealing temperature. Low-temperature annealing was confirmed to significantly improve the dynamic strength. In particular, the yield strength and final flow stress of the annealed HEAs at 300 °C were demonstrated to be as high as 1178.2 MPa and 1797.9 MPa, which was 113.6 % and 54.5 % higher than that of the as-cast counterparts, respectively. Our results revealed that this substantial increase in strength came from a combination of mechanisms, involving dislocation, twinning and fine grain strengthening. In addition, the energy absorption per unit volume of HEAs annealed at 300 °C at maximum strain was measured to be as high as 308.05 MJ/m³ (only 262.55 MJ/m³ for the as-cast counterpart), indicating excellent energy absorption capability. Our investigation reveals the dynamic deformation behaviors and mechanisms of FeCoCrNiCu HEAs, providing valuable guidance for designing and developing HEAs with excellent mechanical properties under dynamic loading.