Influence of Si addition on the microstructure, mechanical and wear properties of as-cast Al0.43CoCrFeNi2.1 high-entropy alloys and performance enhancement by cold rolling and annealing

• Si addition to Al0.43CoCrFeNi2.1 HEAs promotes formation of BCC1/BCC2 phases, leading to a multiphase FCC/(BCC1/BCC2) structure that significantly enhances hardness and tensile strength. • Increasing Si content improves microhardness by ~42% and tensile strength by ~55%, reaching 2.359 GPa and 785 MPa, respectively, while also enhancing wear resistance. • Cold rolling and annealing at 800°C for 1 hour further boosts microhardness to 3.68 GPa and tensile strength to 1270 MPa, representing 56% and 62% improvements over as-cast state. • Strengthening mechanisms are dominated by intrinsic FCC matrix hardness and BCC1/BCC2 precipitation, with BCC2 strengthening via shear mechanism rather than Orowan bypass.