Microstructure and properties of brazed W-Cu composites and beryllium bronze joint

W-Cu composites and Beryllium bronze dissimilar joints were prepared by induction brazing method using BAg56CuZnSn, BAg50ZnCdCuNi and BAg49ZnCuNiMn, respectively. Interfacial microstructure and mechanical properties of the brazed joints were studied. The results show that all the brazed joints displayed perfectly metallurgical bonded interface. Obvious diffusion zone was formed in bonded interface between braze and beryllium bronze. The fracture of brazed joints all occurred at the brazing interface of W-Cu side, and the joint using BAg49ZnCuNiMn solder obtained the highest strength which reaching 250 MPa. Meanwhile, clear boundary braze/W-Cu interface was also observed. The braze had obviously infiltrated into the W-Cu matrix near their interface, leading to increasing of the interface bonding strength. The addition of nickel in braze further improved the metallurgical bonding of the interface due to the diffusion and mutual dissolution of nickel and tungsten. Furthermore, manganese can refine the grain size of brazed joint and improve the joint strength.