Publikacje

Abstract:

In the present investigation, transient liquid-phase bonding was performed between pure titanium (Grade 2) and stainless steel (X5CrNi 18-10) using nickel foil as an intermediate material. The process was carried out at the temperatures of: 950, 975 and 1000 ° C for 60 minutes under the compressive stress of 2 MPa in a vacuum. The microstructure was investigated using light microscopy and scanning electron microscopy equipped EDS. The metallographic examination shows that the diffusion interfaces are free from cracks. However, Kirkendall voids were observed at the borders of materials. Especially large voids were formed in middle section of the joint prepared using the highest bonding temperature. The structure of the joints on the titanium side was composed of the eutectoid mixture αTi+Ti2Ni and layers of intermetallic phases Ti2Ni, TiNi and TiNi3. The nickel interlayer blocked the diffusion of titanium to stainless steel side at 950 °C bonding temperature and prevented from formation of the Fe-Ti intermetallic layers. The layer of a solid solution γFe+Ni between nickel and stainless steel was observed at the 950 °C processing temperature. The mixture of λ+FeTi+Ti, FeTi+Ti, λ+αFe and λ+χ+αFe phases was formed at 975 and 1000 °C at the nickel-stainless steel interlayer.

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Structural changes during the formation of diffusion bonded joints between titanium and stainless steel