| The brazing ribbons and the as-cast filler metal of Cu68.5Ni15.7P6.5Sn9.3(wt%) which have the same compositions are prepared by means of rapid solidification and ordinary casting method respectively. The melting point, component of the two kinds of filler metals and influence on wettability, microstructure and mechanic property of the brazing joints when technical parameter changes are studied comparatively by the method of XRD, DTA, SEM, EDS and tensile test. The results indicated that the melting point of amorphous ribbons is lower than as-cast one by 4.5℃ and its width of crystallizing is diminished by 3.5℃. Wettability, tensile strength, interdiffusion and metallurgy combination between base metal and filler metals of amorphous filler metal are better than as-cast one. The brazing joints of the two filler metals are both composed of diffusion zone and residual brazing filler one. With the holding time prolongating appropriately, the depth of diffusion, wettability, and tensile strength increase and content of fragile intermetallic compound decreases, but when holding time prolongating excessively, content of fragile intermetallic compound increases, tensile strength decreases.With the brazing temperature increased, the wettability of two kinds of filler metals increases first and then decreases while its tensile strength increases, Alloy elements penetrate through grain boundary of base metal previously. The contents of alloy elements decreases with increasing of diffusion depth . The diffusion ability of Sn is the best among the alloy elements of Sn, P and Ni.The bonding mechanism and interfacial reaction are studied. It shows that before brazing temperature reaches the melting point of amorphous filler metal, the contact reaction and liquid behavior is observed which is composed of Sn rich phase-CuSn alloy and forms liquid channel which accelrrates the diffusion of Ni and P, The bonding mechanism belong totransient liquid phase (TLP) bonding. |
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