Interfacial phase transformation induced by hydrogen in Ti65

Diffusion bonding (DB) of near-α titanium alloys requires high temperatures, which can cause grain coarsening, structural deformations, and degradation of the workpiece’s mechanical characteristics. Although introducing hydrogen can increase the amount of weldable β phase in near-α alloys, the extent of the α→β transformation is often limited. To solve these issues, thermal hydrogen processing (THP) was applied to Ti65, in combination with selective magnetron sputtering of a Ti–Al thin film to promote hydrogen segregation at the bonding interface. This approach induced a continuous βH-phase network traversing the interface, markedly enhancing joint stability and enabling DB of Ti65 at an ultra-low temperature of just 750°C. The strategy offers a viable pathway and process concept for low-temperature DB of near-α titanium alloys. (https://doi.org/10.1002/rar2.70089)