Formation mechanism of shear band in Fe₇₀Co₅Ni₈Ta₆W₁₁ high-entropy alloy under quasi-static loading

Shear band is a prevalent failure mode in metallic materials under high strain-rate loading. Recent studies suggest that structural softening mechanisms, including dynamic recrystallization, could play a significant role in the initiation of the shear band. Under quasi-static loading conditions, the mechanisms driving shear band formation in high-entropy alloys (HEAs) remain poorly understood. In this study, a Fe₇₀Co₅Ni₈Ta₆W₁₁ (at. %) HEA was fabricated and tested under quasi-static compression. The HEA samples exhibited the fracture along the shear band. A detailed microstructural analysis at different strains was conducted to examine the evolution of the shear band. The results showed that structural softening, caused by deformation incompatibility between the BCC phase and Laves phase in HEA, facilitated shear band formation. This study provides more understanding for the formation of shear bands caused by microstructural heterogeneity of multi-phase HEAs under quasi-static loading conditions.