Flow Behavior and Microstructure of Hot-Worked TiNbTaVW Refractory High-Entropy Alloy

The high-temperature deformation behavior of an equiatomic TiNbTaVW refractory high entropy alloy (RHEA) was studied at temperatures of 950, 1000, and 1050 degrees C and a strain rate of 10-3 s-1. The flow stress, high-temperature strength, and softening mechanisms were analyzed and compared with the IN718 nickel-based superalloy. The results indicate that the flow stress of both TiNbTaVW and IN718 is sensitive to deformation temperature, with high temperatures resulting in reduced flow stress. Globular grains and elongated grains were observed at 950 and 1000 degrees C for TiNbTaVW, signifying both dynamic recovery and dynamic globularization as the softening mechanisms. Globular grains were only observed at 1050 degrees C for TiNbTaVW, signifying dynamic globularization as the softening mechanism. The TiNbTaVW RHEA has a higher temperature strength of 910, 870, and 658 MPa compared to the IN718 alloy with 72, 87, and 61 MPa at 950-1000 degrees C/10-3 s-1. By demonstrating comparable or superior performance in specific aspects, RHEAs can be considered in the near future for potential applications traditionally dominated by nickel-based superalloys. TiNbTaVW refractory high entropy alloy (RHEA) exhibits superior temperature strength compared to the IN718 alloy at 950-1050 degrees C/10-3 s-1. Globular and equiaxed grains signify dynamic recrystallization, while elongated grains signify dynamic recovery, as evidenced by microstructures of TiNbTaVW and IN718 at all deformation temperatures. This investigation sheds light on the softening mechanisms for the TiNbTaVW RHEA during high-temperature deformation.image (c) 2024 WILEY-VCH GmbH