Coupling effects of temperature and strain rate on the deformation behavior of an equiatomic refractory high‐entropy alloy

Abstract The extraordinary high‐temperature strength of refractory high‐entropy alloys makes them promising candidates for critical engineering applications in extreme service environments, particularly under combined high‐temperature and high‐strain rate loading conditions. This study investigated the coupling effects of temperature (293–1273 K) and strain rate (0.001–3000 s −1 ) on the mechanical behavior and deformation mechanisms of an equiatomic TiZrNbVTa refractory high‐entropy alloy with a single body‐centered cubic structure. The alloy exhibits an exceptional combination of strength and ductility within the selected temperature and strain rate ranges. Microstructural analysis reveals that multiple deformation mechanisms, including severe lattice distortion, kink band formation, stress‐induced martensite transformation from body‐centered cubic to the omega phase, and third‐type strain aging, occur over the considered wide range of temperatures and strain rates. These mechanisms significantly enhance the strength–ductility performance of the alloy, particularly under extreme conditions. Third‐type strain aging occurs at different strain rates, shifting to a higher temperature range as strain rate increases. Zr atoms act as “solute atoms” forming short‐range clusters, thereby pinning moving dislocations. Finally, a deformation mechanism map is proposed, spanning a wide range of temperatures and strain rates. This study provides valuable insights into the design of refractory high‐entropy alloys for extreme thermos‐mechanical applications.