Analysis of deformation behavior of VCoNi medium-entropy alloy at temperatures ranging from 77 K to 573 K

The deformation behavior of VCoNi medium-entropy alloy at the temperatures ranging from 77 K to 573 K was experimentally investigated in this study. It showed that the high-density nanosized dislocation substructures and deformation twins played a major role in the tensile deformation at 77 K, and their synergistic effects caused an excellent combination of strength and ductility. When the temperature is higher than 473 K, the stress-strain curve exhibited obvious a clear serrated flow behavior but maintained good uniform elongation. The microstructure analysis indicated that a dynamically precipitated V-rich phase had an apparent influence on the deformation behavior above 473 K. Present results suggested that although the VCoNi alloy exhibited excellent mechanical properties in the present temperature range, the decreased FCC stability should be noticed, which could result in some changes of mechanical properties particularly at higher temperatures.