Joining of TiAl intermetallic by self-propagating high-temperature synthesis

This study reports on a novel approach for joining TiAl by self-propagating high-temperature synthesis (SHS). The Ti, Al and C powders were applied in the joining process with the assisted electromagnetic field. The microstructure analysis revealed that a dark TiAl₃ reaction layer existed at the interface. The TiC particles and multi-layer granular structures of the Ti-Al system were found in the reaction products. It was noted that the porosity was inevitable in direct SHS joining. In order to improve the joining quality, Ag-based brazing foil was inserted between the powder compacts and the TiAl substrate. Molten brazing alloy during SHS reaction improved the wettability of the interlayer to TiAl substrate and filled well into the holes in the reaction products. With the application of Ag-based brazing alloy, the density increased and the joining quality improved.