Diffusion bonding of Ti6A14V using encapsulation-free hot isostatic pressing

Vacuum brazing was used as a pre I IIP (Hot Isostatic Pressing) process to seal the periphery of Ti6Al4V bonding couples so that the parts can afterwards he diffusion bonded using encapsulation free HIP. The microstructures of the braze affected zone and of the bonded interface were studied using analytical scanning electron microscopy. It was shown that the braze affected zone can be restricted to an area of a few hundred microns in dimensions whilst using a relatively wide processing window. A homogeneous microstructure was retained in the main part of the bonds, which was not influenced by the brazing process. The tensile and fatigue properties of bonded samples were assessed and compared with those of the bulk starting material. The present study suggests that vacuum brazing can be used as an economic substitute for encapsulation before HIP diffusion bonding of titanium components.