Investigation on the microstructure, mechanical and electrical properties of Ti₃SiC₂/Cu joint obtained by Ti₂₅Zr₂₅Ni₂₅Cu₂₅ amorphous high entropy alloy and Ag composite filler

Ti₃SiC₂/Cu brazed joint has an important application in the pantograph of high-speed trains, but excessively continuous intermetallic compounds (IMC) and thick diffusion reaction zone (DRZ) in the joint are detrimental to both the mechanical and electrical properties of the joint. Therefore, regulating the interfacial microstructure is an effective way to acquire an excellent brazed joint. In this study, Ti₂₅Zr₂₅Ni₂₅Cu₂₅ amorphous high entropy alloy (HEA) was fabricated, and the brazing of Ti₃SiC₂ to Cu was carried out by the Ti₂₅Zr₂₅Ni₂₅Cu₂₅ HEA and Ag foil composite filler. The hysteresis effect of the HEA effectively slowed down the interfacial atomic diffusion and metallurgical reactions, which is conducive to the formation of relatively thin DRZ. Due to the combination of Ag foil and the HEA, the IMC distribution in the joint obtained at a relatively low temperature is more dispersed and uniform. Under the optimal brazing conditions, the maximum shear strength of the brazed joint obtained with the Ti₂₅Zr₂₅Ni₂₅Cu₂₅ and Ag composite filler is 34.85% higher than that obtained with Ag-26.7Cu-4.5Ti conventional filler. In particular, the electrical resistance of the joint obtained with the composite filler is 20.35% lower than that obtained with the single Ti₂₅Zr₂₅Ni₂₅Cu₂₅ HEA filler.