Designing a low-melting Sn6Ag7Ni4Co2Ti high entropy alloy filler to optimize microstructure and mechanical properties of Ti3SiC2/Cu joint

Brazing Ti3SiC2 ceramic to pure copper can expand their practical applications, but excessive brittle intermetallic in the joint is harmful to mechanical properties of joint. The key to acquire a high-quality brazed joint is to control the microstructure in brazing seam and diffusion reaction zone at Ti3SiC2 ceramic side. Herein, Sn6Ag7Ni4Co2Ti low-melting high entropy alloy was fabricated and brazed to acquire a defect-free Ti3SiC2/Cu brazed joint. Through careful characterizations of the interfacial reaction products, the influence of novel HEA filler was clarified. The high-entropy effect and hysteresis effect of HEA filler effectively reduced the rate of atomic, and metallurgical reaction was also slowed down, which is beneficial to maintain a simple interface structure. The interface of Ti3SiC2/Cu joint brazed with Sn6Ag7Ni4Co2Ti HEA filler is mainly composed of Ag (s, s), Cu (s, s), Cu3Sn and FCC-base solid solution. Due to the thin diffusion reaction zone and solid solution, the maximum shear strength of 60.55 +/- 3.45 MPa was achieved when the joint was brazed at 1000 degrees C for 10 min. This is 34.85% more than the joint brazed with Ag-26.7Cu-4.5Ti filler under its optimal brazing parameter.

Automated summary

The study found that using Sn6Ag7Ni4Co2Ti low-melting high entropy alloy as filler can achieve a defect-free Ti3SiC2/Cu brazed joint. The high-entropy effect and hysteresis effect of the alloy effectively reduce the rate of atomic diffusion and slow down the metallurgical reaction, which is beneficial to maintain a simple interface structure. The joint brazed with Sn6Ag7Ni4Co2Ti HEA filler achieved a maximum shear strength of 60.55 +/- 3.45 MPa, which is 34.85% higher than the joint brazed with Ag-26.7Cu-4.5Ti filler.