WEAR-RESISTANT SURFACES ON HIGH-TEMPERATURE TITANIUM-ALLOY AND TITANIUM ALUMINIDE BY DIFFUSION BONDING

Titanium alloys have pool tribological performance and there is consid erable interest in producing wear resistant surfaces on titanium. An F e-Ni alloy (IN 907) and a nickel alloy (HS 242) have been diffusion bo nded to the high temperature titanium alloy IMI 829 and to the titaniu m aluminide (Ti, Al) alloy, Super Alpha-2. A combination of tantalum a nd nickel interlayers has been used to aid bonding. Using these interl ayers, increased joint shear strengths were measured and the plastic d eformation to failure was increased. Thermal cycling trials have been performed to assess the elevated temperature performance of some of th e joints. A reduction in shear strength after thermal cycling was foun d for joints with tantalum and nickel interlayers and this was associa ted with the oxidation of tantalum. Oxidation protection for the tanta lum and nickel interlayers would be required for titanium alloys to be used in service above similar to 450 degrees C.