The prospects for joining titanium aluminides

This paper reviews relevant published data and presents some new data on the joining of titanium aluminides. Some of the problems encountered in the development of suitable joining procedures for both α2 and γ titanium aluminides are described, together with current progress in resolving these problems. The difficulties highlighted include the lack of data on transformation kinetics (particularly for γ alloys), the potential for hydrogen embrittlement, the low ductility of the material and the lack of suitable welding consumables. However, there is no evidence for any susceptibility to hot cracking. loys have been welded successfully by several methods, including fusion processes, such as gastangsten arc (GTA), laser and electron beam welding, and solid state processes, such as friction welding and diffusion bonding. However, there is little information on the mechanical properties of the welds, in particular at high temperatures. portance of thorough metallographic studies of welded joints is emphasized, as this is considered to be a vital step in understanding the complex relationships between the welding procedure, microstructure and mechanical properties. Such an understanding is an essential prerequisite to the development of optimized joining procedures.