Solid-state diffusion bonding of gamma-TiAl alloys using Ti/Al thin films as interlayers

Abstract

Alternating nanometric layers of titanium and aluminium were used as filler material to promote joining between titanium aluminide samples. The improved diffusivity of these nanometric layers is thought to overcome the difficulties in solid-state joining of titanium aluminides without producing chemical discontinuities at the interface. In this study, a thin multilayer (alternating titanium and aluminium layers), 2 mm thick, was deposited by dc-magnetron sputtering onto the two surfaces to be joined. The effects of processing conditions and the thickness of nanometric layers on microstructure and chemical composition variation across the interface have been analyzed. Sound regions can be obtained at temperatures as low as 600 C but higher temperatures (800e1000 C) are needed to obtain completely sound joints. During processing, the asdeposited film evolves to a nanocrystalline TiAl layer which may explain why the bond region is slightly harder than the base material.

Fretting wear behaviour of double-glow plasma Cr–Nb coating on γ-TiAl alloy

“…Furthermore, Ti and Al were both detected in the diffusion layer as well, confirming the outward diffusion process of elements into the coating zone. This was beneficial to the interfacial bonding strength of the coating 20,21 , as confirmed by the scratch-test results. The nano-indentation results showed that the surface hardness of Cr-Nb coating was improved from 5.9GPa to 9.5GPa compared with the TiAl substrate.…”

Recrystallization Behavior at Diffusion Bonding Interface of High Nb Containing TiAl Alloy

“…[10,11] Simões et al [12][13][14][15] carried out the diffusion bonding of TiAl alloy by using nano-scaled Ni/Al as interlayer and the bonding temperature was reduced to 900 C without decreasing the bonding strength. Except for Ni/Al nanolayers, the Ti/Al foil [16][17][18] was also applied as an intermediate element to produce sound joints of g-TiAl-based alloys. However, a common challenge in applying interlayers for bonding TiAl alloys is the size and shape limits of components, because the nanolayers are difficult to be used in a TiAl component with complex mating surfaces or large size.…”

Diffusion welding of γ-TiAl based alloys through nano-layered foil of Ti/Al system

“…Promising results were obtained at diffusion welding samples from g-TiAl alloy on which surfaces were deposited with thin nanolayered Ti/Al coatings [1,2]. Simplification of the technology of producing the permanent joints can be achieved in the case of application of nano-layered materials in the form of foil, which could be placed between the surfaces to be joined [3].…”