Wear resistant surfaces on high temperature titanium alloy and titanium aluminide by diffusion bonding

Abstract

Titanium alloys have poor tribological performance and there is considerable interest in producing wear resistant surfaces on titanium. An Fe-Ni alloy (IN 907) and a nickel alloy (HS 242) have been diffusion bonded to the high temperature titanium alloy IMI 829 and to the titanium aluminide (Ti₃Al) alloy, Super Alpha-2. A combination of tantalum and nickel interlayers has been used to aid bonding. Using these interlayers, increased joint shear strengths were measured and the plastic deformation to failure was increased. Thermal cycling trials have been performed to assess the elevated temperature performance of some of the joints. A reduction in shear strength after thermal cycling was found for joints with tantalum and nickel interlayers and this was associated with the oxidation of tantalum. Oxidation protection for the tantalum and nickel interlayers would be required for titanium alloys to be used in service above ∼ 450°C.