| Pulse-pressuring diffusion bonding (PPDB) of TA17 titanium alloy to 0Cr18Ni9Ti stainless steel was carried out with direct diffusion bonding and diffusion bonding of nickel interlayer in this paper, and the bonding process was optimized. Microstructure observation, micro-hardness testing, SEM observation, EDS determination and XRD analysis were employed to investigate the structure of the joint and phases on the tensile fracture. The relationship between technique parameters and joint strength was also studied. The formation and mechanism of interface reaction between 0Cr18Ni9Ti and TA17 was studied. The interface contact stress of diffusion bonding was analyzed. The process and variation of stresses of diffusion bonding were simulated.PPDB of titanium alloy to stainless steel was optimized and perfected. Under conditions of bonding temperature 825℃, pulse pressure 8～50MPa, pulse pressuring cycles 30 cycles, frequency 0.5Hz, preserved temperature for 0s before pulsing and 120s after pulsing. The time for bonding was only 180s under the optimum situation, and the joint strength reached 321MPa. The interface-structure of titanium alloy/stainless steel joint was investigated, and according to the formation-mechanism of interface-structure it was found thatγ-Fe /σphase / Fe2Ti/ FeTi /β-Ti /α-Ti layered structure were formed on the bonding interface. According to the test of fracture's breadcrust and the micromechanics of rupture, PPDB joints ruptured around the interface between Fe-Ti intermetallic compounds andβ-Ti layers in the tension test.PPDB of titanium alloy to stainless steel was carried out with nickel interlayer with a thickness of 13μm, and the optimized parameters for PPDB were gained as follows: bonding temperature was 875℃, impact pressure was 8～50MPa, impact pressuring times was 30 cycles, frequency was 0.5Hz, preserved temperature for 0s before impact and 120s after impact. The time for bonding was only 180s under the optimum situation, and the joint strength reached 334MPa. The interface-structure of titanium alloy/nickel foil/stainless steel joint was investigated, and according to the formation-mechanism of interface-structure it was found thatγ-Fe /σphase / Fe-Ni solid solution/pure Ni/Ni-Ti intermetallic compounds/β-Ti/α-Ti layered structure were formed on the bonding interface. According to the test of fracture's breadcrust and the micromechanics of rupture, PPDB joints ruptured around the interface between Fe-Ni solid solution and Ni-Ti intermetallic compounds,β-Ti layers in the tension test. |
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