Brazing joining of Ti₃AlC₂ ceramic and 40Cr steel based on Ag-Cu-Ti filler metal

The following paper investigated the vacuum brazing joining of Ti₃AlC₂ ceramic and 40Cr steel with Ag-Cu-Ti filler metal at 850 °C. A characterization of the brazing joint revealed that it consisted of the Ti₃AlC₂ ceramic, the brazing seam, and the 40Cr steel. There were four phase types found in the brazing seam that included AlCu2Ti, Al4Cu9, Cu[s, s], and Ag[s, s]. These occurred as a result of the interface reactions, which precipitated from the liquid alloy during solidification. When the brazing time was increased from 10 min to 30–60 min, there was a formation of a continuous reaction layer and a strong combination at the filler metal/40Cr steel interface. This led to the transformation of the joint facture position from the filler metal/40Cr steel interface to the Ti₃AlC₂/filler metal interface, thus resulting a significant enhancement of the joint shear strength from 27.7 MPa (10 min) to 196.4 MPa (30 min), and again to 191.3 MPa (60 min). The results showed that the optimal brazing time was 30 min.