Studies On Phase Interface Reaction Of Fe-Ni-Ti Ternary System

The migration of phase interface in diffusion bonding is up to the diffusion and dissolution of atoms at the interface, so it is very important to research the diffusion of atoms at different phase interface. The Fe-Ni-Ti diffusion triple specimens were made by riveting method to research the interface behavior. After a series of heat treatment under different conditions, diffusion zones between the components are formed from the compact contact of the bulks of the components. The microstructure characteristics of the diffusion zones were studied by means of optical metallography and SEM backscattering technique. The results show that the diffusion phenomena at triple points in the specimens are affected by the mechanical technics of preparing specimens. With the help of the Photoelectron Spectroscopy and phase diagram, it has been shown that there are no ternary intermetallic compounds when the Fe-Ni-Ti diffusion triple are annealed at 850℃for 200 hours. The phases of diffusion layer region at triple points, respectively, are the Fe/Ti intermetallic compound with a mixture of Ni and Ti/Ni intermetallic compound with a mixture of Fe.The interfaces between diffusion layers and matrix and interface between Fe-Ti and Ti-Ni are regular and clear due to intermetallic compounds in the interface The interfaces between diffusion layers and matrix are vague at Fe-Ni interface far away from the triple crunodes, and there is a solid solution in this zone. It has been seen that the diffusion layers become thick when the temperature is high, which shows exponential relationship and the diffusion layers become thick when the annealing time is long, which shows a parabolic relationship. The inborn order of the phases in the diffusion layers is not only influenced by the heat of formation, but also by the concentration of atoms at the interfaces.