Effects of Intermetallic Phases on the Bond Strength of Diffusion-Bonded Joints between Titanium and 304 Stainless Steel Using Nickel Interlayer

Abstract

Solid-state diffusion bonding was used to join commercially pure titanium (Ti) and 304 stainless steel (SS) with a pure nickel (Ni) interlayer of 300-lm thickness in the temperature range of 800°C to 950°C in steps of 50°C for 7.2 ks under 3 MPa load in vacuum. Interfaces were characterized using light and scanning electron microscopy. The interdiffusion of the chemical species across the diffusion interfaces was evaluated by electron probe microanalysis. Nickel interlayer completely restricted the migration of Ti to SS up to 850°C bonding temperature. However, at 900°C and 950°C processing temperatures, Ni interlayer could not restrict the migration of Ti to SS, and phase mixtures of k + v + a-Fe, k + a-Fe, and k + FeTi + b-Ti were formed at SS-Ni interface. The occurrence of different intermetallics was confirmed by X-ray diffraction technique. The maximum tensile strength of~311 MPa and shear strength of 236 MPa along with 9.1 pct elongation were obtained for the diffusion couple processed at 850°C due to better contact between the mating surfaces and without formation of brittle Fe-Ti base intermetallics. With an increase in thebonding temperature to 900°C and above, the bond strength drops due to the formation of brittle Fe-Ti base intermetallics in the diffusion zone.Observation of the fracture surface in a scanning electron microscope (SEM) using energy dispersive spectroscopy demonstrates that failure occurred through Ni-Ti interface of the joints when processed up to 850°C and through SS-Ni interface when processed at 900°C and above.

Effect of alloying elements on interdiffusion phenomena in explosive clads of 304LSS/Ti–5Ta–2Nb alloy

“…In contrast, Taguchi et al [18] have reported a high value of 360 kJ mol -1 for growth of bTi(Fe) phase during annealing in the temperature range of 677-867°C. Hence, it is obvious from literature that the presence of intermetallic phases and secondary phases at the interface control the overall growth of the reaction zones [19].…”

Mechanical properties and deformation behaviour of laminated titanium-intermetallic composites synthesised using Ti and Cu foils

“…The Ti-intermetallics interface is characterised by the presence of a light-shaded reaction zone containing β-Ti and the Widmanstätten α-β-Ti structure. The migration of copper atoms to titanium lattice lowers the eutectoid transformation temperature of titanium since copper is a strong β-stabilising element [25]. During cooling, α-β-phase aggregate forms due to the decomposition of β-Ti.…”

THE INFLUENCE OF TEMPERATURE AND TIME OF PRESSURE WELDING ON THE FORMATION OF A JOINT BETWEEN THE TITANIUM ALLOY AND Ni-2 %Cr ALLOY

“…Для преодоления этой проблемы S. Kundu с соавторами предложили ис-пользовать никелевую прослойку [11][12][13][14]. Были иссле-дованы соединения с нержавеющей сталью как техни-чески чистого титана [11][12][13], так и сплава типа ВТ6 [14], при этом авторы использовали никелевую про-слойку с крупнозернистой микроструктурой.…”