Enhancing strain hardening and strength-plasticity synergy upon dynamic loads in refractory high-entropy alloys via B2 ordering and spinodal decomposition

Abstract

Refractory high-entropy alloys (RHEAs) demonstrate significant future for high-strain-rate applications. However, thermal softening-induced loss of strain hardening generally causes post-yield plastic instability and catastrophic failure in conventional RHEAs. Here, we utilize spinodal decomposition indued by Al addition to develop a TiZrNbTaAl_0.3 RHEA featuring a coherent BCC+B2 basket-weave. The ordered B2 frameworks and disordered BCC cuboidal phases architecture exhibits strong resistance for dislocation shearing and adiabatic temperature rise then provides strong dislocation pinning forces during dynamic deformation. The promoted multidirectional dislocation interactions through dislocation loop expansion mechanisms and in-situ grain refinement via deformation-induced substructure segmentation enhance the dislocation multiplication. Consequently, TiZrNbTaAl_0.3 RHEA achieves unprecedented strain hardening capacity (Δσ = σ_U-tru - σ_Y-tru = 912 MPa) at 5400 s⁻¹, ultimately delivering simultaneous enhancements in strength (σ_Y-eng = 1813 ±15 MPa, σ_U-eng = 3753 ±21 MPa) and plasticity (ε_U >40% with uniform strain ∼30%). This study provided valuable insights for optimizing the dynamic mechanical properties of RHEAs.