Joining SiCf/SiC composites to Al0.3CoCrFeNi high-entropy alloys with a Cu–Ti filler alloy: Interfacial reactions, high-entropy effects, and mechanical properties

Abstract

SiCf/SiC composite and Al0.3CoCrFeNi high-entropy alloys, which are valued as promising candidate materials for nuclear reactors, were successfully brazed together, achieving the maximum strength of 59 MPa at room temperature and 49 MPa at 700 °C. The high-entropy effect and its deviation caused by the unavoidable elemental segregation in brazing were uniquely considered. It was proved that the Si from ceramics or the Ti from fillers usually caused segregation by increasing the enthalpy, which raised doubts whether high-entropy alloys could play an expected role in brazing some specific materials. The microstructural evolution, mechanical properties, and fracture modes of the joints were identified in detail. The erosion of metal atoms to the SiCf/SiC composite was observed from the directions perpendicular and parallel to the interface, which presented a fiber-orientation-dependent manner.