Investigating the effect of WC reinforcements in Cu–Ti composite filler on the microstructural evolution and mechanical characteristics in brazing C_f/SiC and GH3536

The high residual stress and weak interface derived from the characteristics of C_f/SiC and superalloy have greatly limited the mechanical characteristics of their brazed joints. Low coefficient of thermal expansion reinforcement is introduced to reduce residual stress through reducing the thermal mismatch of joints, whereas the other properties have greatly influenced their mechanical characteristics. This study investigated the effect on the microstructural evolution and mechanical characteristics of C_f/SiC-GH3536 joints through introducing WC within Cu–Ti composite filler. The atomic structure of Fe-W-Ni-Cr-Cu multi-principal element alloy (MPEA) produced by the in-situ reaction of WC and Cr(s,s) was revealed by spherical aberration corrected transmission electron microscope. MPEA improved the load-carrying capacity of C_f/SiC-GH3536 brazed joints for absorbing strain energy. Specifically, the interlocking interface between MPEA and by Cu(s,s) reduced the phase boundary mismatch compared to Cr(s,s) and Cu(s,s) in original joints. As a result, the highest joint shear strength was 74.3 MPa, 94 % stronger than that of Cu–Ti. This research elucidates the underlying strengthening mechanisms of reinforcements in brazed joints.