Abstract: Adiabatic shear susceptibility is a critical factor to determine the penetration performance for kinetic energy penetrators. The presence of microstructural heterogeneities, such as the differential strength among constituent phases, could facilitate the early onset of shear localization. Nevertheless, the specific roles of each phase, along with the distinct features influencing adiabatic shear band formation in multi-phase alloys, remain unclear. Here, we report that the adiabatic shear susceptibility as well as dynamic mechanical properties can be tailored in multi-phase W-Fe-Ni-Mo high-entropy alloys (HEAs), which consist of a face-centered cubic phase (FCC), a body-centered cubic phase (BCC), and a rhombohedral μ phase. Specifically, W₂₅Fe₁₅Ni₂₅Mo₃₅ alloy achieves a fracture strength of 1958 MPa and fracture strain of nearly 40 %. Moreover, adiabatic shear susceptibility was greatly improved (critical shear strain 3.3) and the role of each phase in adiabatic shear band evolution was revealed. The reduction of FCC phase weakens the strain hardening ability, facilitating dynamic recrystallization in the BCC and μ phases, which enhances the softening mechanism. This study provides a pathway to achieving a synergistic combination of high dynamic mechanical properties and superior adiabatic shear susceptibility via controlling multi-phase microstructures of HEAs.

Key words: High entropy alloy, Multi-phase, Adiabatic shear band, Phase engineering