Negative thermal expansion of LiAlSiO₄ interlayer with AgCuTi filler for brazing SiC joints

In order to relieve the residual stresses generated in SiC joints during brazing, LiAlSiO₄-reinforced AgCuTi/Cu-foam composite interlayer was prepared. The typical interfacial structure of SiC joints was SiC/TiC/Ti₅Si₃ + Cu₄Ti₃ + CuTi + LiAlSiO₄ + Cu (s, s) + Ag (s, s)/TiC/Ti₅Si₃/SiC. The effects of different process parameters and LiAlSiO₄ additions on the microstructure and shear strength of the joints were investigated. The maximum shear strength of SiC was 118.7 MPa at 890°C for 10 min with LiAlSiO₄ addition of 1 wt%, which is 94.5 MPa higher than that of SiC joints without LiAlSiO₄. In addition, the theoretical calculations effectively proved that the addition of LiAlSiO₄ can relieve the residual stresses in the joints effectively.