Dynamic compression behavior of single-phase and dual-phase Fe-rich medium-entropy alloys

The compressive mechanical behavior and deformation mechanisms of Fe-rich medium-entropy alloys with different phase structures were investigated under quasi-static (10⁻⁴ - 10⁻² s⁻¹) and high strain rates (1500 - 6000 s⁻¹) conditions. The results indicated that no fractures or cracks occurred in any of the compressed specimens of the single-phase Fe₅₇Ni₁₈Cr₁₅Si₇Al₃ and dual-phase Fe₆₂Ni₁₃Cr₁₅Si₇Al₃ alloys. Under quasi-static conditions, both alloys exhibited low strain rate sensitivity, with deformation primarily characterized by high-density dislocations and minimal deformation twins or stacking faults. At high strain rates, the yield strength increased significantly. The strain rate sensitivity coefficients (m_d) for the single-phase and dual-phase alloys were 0.081 and 0.089, respectively. In the single-phase alloy, deformation was accompanied by high-density dislocations, deformation twins, and the presence of deformed NiAl precipitates. The dual phase alloy exhibited a more pronounced transformation-induced plasticity effect. At a strain rate of 6000 s⁻¹, the adiabatic temperature rise reached 178 K for the single-phase alloy and 149 K for the dual-phase alloy. These findings indicated that Fe-rich medium-entropy alloys possessed excellent strength and plasticity under high strain rates, ensuring their reliability in dynamic impact environments.