| In this paper, the phase transformation superplastic of nearα-phase titanium alloy TA17 was testified at first. It was not only analyzed qualitatively, but also was quantified by comparing with the strain of titanium alloy gotten from constant temperature and pressure.The solid-state diffusion bonding with nickel interlayer of nearα-phase titanium alloy to 0Cr18Ni9Ti austenite stainless steel under phase transformation superplastic state was carried out on Gleeble-1500D.The nickel interlayers were added in the form of nano-nickel powder, nano-nickel coating and nickel foil respectively. Metalloscope observation, SEM observation, EDS determination and XRD analysis were employed to research on the structure of the joint and phase on the fracture surface. The effect of different nickel interlayers on the fracture of joint was also analyzed. The results were listed as following:The maximum of joint strength was 212MPa when nano-nickel powder interlayer was added. Fracture occurred at the nano-nickel powder interlayer or the interface between nickel interlayer and stainless steel. Lower strength and looser structure of nano-particles interlayer andσphase formed near the interface between nickel interlayer and steel reduced the joint strength.The maximum of joint strength was 258MPa with a nano-nickel coating interlayer. Because of the accidented and dense pored surface of nano-nickel coating, it is difficult for nickel interlayer and titanium alloy to reach close contact. When the upper temperature of bonding was 910℃and 930℃, fracture occurred at the interface between nickel interlayer and titanium alloy where were not bonded. At the both side of fracture surface, Fe atom was not found. It meant the barrier effect of nickel coating interlayer was good and intermetallic compounds between titanium alloy and iron were avoided. When the upper temperature of bonding were 950℃and 970℃,fracture occurred mainly at the interface betweenβ-Ti and Ti-Fe, Ti-Ni intermetallic compounds. This site was the zone of weakness when titanium alloy and stainless steel were bonded at higher temperature.The strength of joint with nickel foil was as high as 292MPa.The results of analysis showed thatγ-Fe,σphase, Ni, Ni3Ti, NiTi, NiTi2,β-Ti andα-Ti layers were formed around the joint interface, and the brittle intermetallics of Ti-Fe series were avoided.
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