Achieving synergistic strength-ductility in a novel refractory high-entropy alloy from room to high temperatures through nano-silicide precipitation-mediated dislocation dynamics

Abstract

Refractory high-entropy alloys (RHEAs) face critical challenges in reconciling room-temperature ductility with high-temperature strength retention and microstructural stability for extreme-condition applications. Here, we develop a novel non-equimolar and low-density (V₃₀Nb₄₀Ti₂₀Ta₁₀)₉₉Si₁ RHEA (7.91 g/cm³) that achieves unprecedented synergy of ambient deformability and elevated-temperature performance via nano-silicide precipitation engineering and dislocation dynamics optimization. The alloy achieves an exceptional strength-ductility synergy at room temperature (yield strength: 958 MPa, fracture strain: 33.1 %, uniform tensile elongation: 15.7 %) via nano-silicide-mediated cross-slip, multi-planar slip, and hierarchical dislocation substructure evolution. At 1000 °C, the alloy retains 258 MPa yield strength with 76 % elongation, outperforming conventional wrought superalloys. Multiscale analysis reveals that the combined effects of precipitation strengthening and DRX-driven microstructure evolution allow (V₃₀Nb₄₀Ti₂₀Ta₁₀)₉₉Si₁ to preserve its mechanical integrity under severe thermomechanical environments. Long-term heat exposure (120 h at 1000 °C) proves the alloy's high stability, exhibiting negligible microstructural evolution and >99 % strength retention. The balance of mechanical properties and microstructural stability enables the novel RHEA to stand out among RHEAs. This study offers critical insights into designing RHEAs that achieve a balance of ambient deformability, high-temperature strength, and microstructural stability, thereby enhancing their potential for aerospace and turbine material applications.