Microstructure and mechanical properties of Al_0.3CoCrFeNi brazed by the TiZrNiCu brazing filler

High-entropy alloys (HEAs) offer exceptional properties for advanced applications, yet reliable joining techniques remain challenging. This study investigates the microstructure and mechanical properties of Al_0.3CoCrFeNi HEA brazed with a TiZrNiCu filler at 960 °C for 10 min. The TiZrNiCu filler, characterized by an amorphous structure with a melting point at ∼835 °C, ensures thermal compatibility with the HEA. The optimal joint exhibits a balanced microstructure comprising Ti₂(Ni, Cu) intermetallic compounds (IMCs), C15 Laves phases, Ti (s, s) solid solution, σ phases, and body-centered cubic (BCC) solid solution phases. Room-temperature shear strength peaks at ∼153 MPa under these conditions, demonstrating a tradeoff between strength and ductility. Microstructural evolution reveals Ti/Cu diffusion from the filler, elemental redistribution driven by base-metal/IMC interactions, and the formation of solid solution and IMC phases. Fracture analysis indicates that 10-min brazing minimizes brittle phases while maintaining a balanced microstructure. This work establishes TiZrNiCu as a promising medium-entropy brazing filler for HEAs, balancing process efficiency and joint performance.