Effect of SiC adiition on microstructure and mechanical properties of the W/AgCuTi/Cu brazed joint

To study the effect and mechanism of SiC addition on relieving residual stress in tungsten-copper brazed joints, several W/SiC-AgCuTi/Cu brazed joints with different SiC contents were obtained using vacuum brazing technology. The microstructure evolution and shearing properties of the joints were analyzed. The results show that the shear strength of the brazed joint initially increases and then decreases with increasing SiC addition. When the addition of SiC increases to 10%, the shear strength of the brazed joint reaches 120 MPa, 45% higher than that of the welded joint without SiC. It was proposed that a small amount of SiC (0 − 10%) can be uniformly distributed in the W-Cu brazed joint, effectively relieving welding residual stress and improving joint strength. However, excess SiC (20%) tends to aggregate into large blocks in the joint, resulting in stress concentration during shearing, which counteracts strengthening of the W-Cu brazed joint.