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 con-ventional 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.

Automated summary

By using Ti25Zr25Ni25Cu25 amorphous high entropy alloy (HEA) as filler material and combining it with Ag foil, the interfacial microstructure of Ti3SiC2/Cu brazed joint can be regulated to obtain a good joint. The hysteresis effect of the HEA effectively slows down interfacial atomic diffusion and metallurgical reactions, resulting in a relatively thin diffusion reaction zone (DRZ). The combination of Ag foil and HEA ensures a more dispersed and uniform distribution of intermetallic compounds (IMC) in the joint. The maximum shear strength of the joint obtained with the Ti25Zr25Ni25Cu25 and Ag composite filler is 34.85% higher than that obtained with Ag-26.7Cu-4.5Ti conventional filler, and the electrical resistance is 20.35% lower than that obtained with the single Ti25Zr25Ni25Cu25 HEA filler.