A detail study focussing the microstructural evolution of the interfacial zone in the course
of the processing of Ti-47Al-2Cr-2Nb joints using Tini 67 as filler alloy was carried out in this
investigation. Experiments, aiming the understanding of the mechanisms that promote the melting
of the braze alloy, were performed below the solidus temperature of the filler, at 750 and 900°C.
Diffusion brazed samples were joined at 1000 and 1100°C, with no dwelling stage and subsequently
quenched in water in order to frozen the microstructure formed at the bonding temperature. The
interfaces were analysed by scanning electron microscopy (SEM) and by energy dispersive X-ray
spectroscopy (EDS), respectively. In the course of the heating stage, several single phase layers
were formed within the filler alloy due to the solid state interdiffusion of Ti and Ni atoms. At
900°C, the microstructure of the filler evolved form the initial Ti (α)/(Ni)/Ti/ (α) layers to a
Ti (β)/Ti2Ni/TiNi/TiNi3/TiNi/Ti2Ni/Ti (β) layered microstructure. The filler alloy begun to melt due
to the eutectic reaction between the contiguous layers composed of Ti (β) and Ti2Ni. After joining,
the main phases detected at the interfaces were α2-Ti3Al, Ti-Ni-Al and Ti-Ni intermetallics. For
joining at 1000°C, a substantial amount of residual filler (Ti2Ni and Ti (α) particles) was also
detected at the central zone of the interface. No marked evidences of residual filler zones were
noticed for joining at 1100°C; instead, a mixture α2-Ti3Al with Ti-Ni-Al or Ti2Ni intermetallics was
detected at the centre of the interface.
