Effect of rolling mode on the microstructure and mechanical properties of dual-phase Fe₂₀Co₂₀Ni₄₀Al₂₀ high-entropy alloy

In response to the urgent need for high-strength and high-plasticity alloy materials, this study systematically investigated the processing of the dual-phase Fe₂₀Co₂₀Ni₄₀Al₂₀ high-entropy alloy (HEA) via four methods: room temperature rolling (RTR), deep cryogenic temperature rolling (DCTR), warm temperature rolling (WTR), and warm/cold circular rolling (WR/CR). By employing multi-scale characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD), the evolution of microstructure, mechanical properties, and their associated strengthening mechanisms were comprehensively analyzed. Mechanical property tests indicate that WR/CR exhibits superior mechanical performance. Specifically, its ultimate tensile strength (UTS) reaches 1186 MPa, and its elongation is 21.16 %, representing respective increases of 34 % and 50.8 % compared to those of the as-cast specimen R0. After WR/CR treatment, the FCC phase accommodates the majority of the deformation. The texture of the FCC phase exhibits a deformed GOSS{011}〈100〉 distribution, whereas the texture of the B2 phase demonstrates a recrystallized S-type{123}<634 > distribution. The enhancement in material performance following WR/CR treatment is primarily attributed to dislocation strengthening, which results from dislocation pinning and dislocation multiplication. EBSD analysis reveals that the dislocation density of the alloy markedly increases after WR/CR treatment, with dislocations exhibiting interphase interface movement. This study demonstrates that WR/CR represents a novel and highly effective method for enhancing the comprehensive mechanical properties of dual-phase HEAs, thereby achieving a synergistic improvement in both the strength and plasticity of dual-phase Fe₂₀Co₂₀Ni₄₀Al₂₀ HEA.