The microstructural evolution and enhanced mechanical properties of in-situ (AlN plus CrC) reinforced Al0.5CoCrFeNi high-entropy alloy composites

Using g-C3N4 as a precursor, the in situ synthesis of (AlN + CrC)-reinforced Al0.5CoCrFeNi high-entropy alloy (HEA) was successfully achieved through the spark plasma sintering process. The nitrogen and carbon sources from g-C3N4 react with Al and Cr to form AlN and CrC, respectively, resulting in a (AlN + CrC)/Al0.5CoCrFeNi composite with a network structure. The introduction of reinforcement particles significantly refines the grains of the composite. The meticulously designed (AlN + CrC)/Al0.5CoCrFeNi composite exhibits a hardness of 589 HV and a tensile strength of 1108 MPa. Compared with high entropy alloy, the increases are 33 % and 28 %, respectively. The fracture mechanism of high-entropy alloys primarily involves ductile fracture, while the composite exhibits both ductile and brittle fracture mechanisms. The in-depth analysis of the reinforcement mechanism of network-structured composite materials reveals that Strengthening mechanism main include load transfer, thermal mismatch, solid solution strengthening, the orowan mechanism and synergistic enhancement of different types of particles at multiple scales.