Study on Bonding Mechanism of Brazing of Amorphous Cu-P Filler Metal

The amorphous Cu68.5Ni15.7Sn9.3P6.5 (wt%) brazing ribbons were prepared by using rapid solidification, which were brazed with red copper at the range of the solidus-liquidus temperature by vacuum brazing and the spreading of melting liquid phase was observed. The microstructure of the interface and the diffusion behaviour of alloy elements were analyzed by means of XRD,EPMA,EDAX and OM. The results show that, below the solidus temperature of brazing ribbons, the contact reaction and liquid behavior is produced, which is composed of Sn rich phase-CuSn alloy, forms liquid channel, and accelerates the diffusion of Ni and P during the initial stage of brazing because of the solid diffusion of Sn. Alloy elements penetrate through grain boundary of base metal previously. The contents of alloy elements decreases with the increase of diffusion depth. The diffusion ability of Sn is the best among the alloy elements.