Joining of the Intermetallic Compound TiAl Using Self-propagating High-temperature Synthesis Reaction

Abstract

The intermetallic compound TiAl was bonded by using self-propagating high-temperature synthesis (SHS) reaction of a mixture of elemental Al and Ti powders used as a filler metal. The structure of SHS reacted filler metal was inhomogeneous and consisted of Ti, {alpha}{sub 2} (Ti{sub 3}Al) and TiAl{sub 3}. On the bonding interface between base metal and filler metal, TiAl{sub 3} was formed as a reaction layer. By the subsequent heat treatment of the SHS joint at 1573 K, the structure of the filler metal changed to a fine lamellar structure consisting of {alpha}{sub 2} and {gamma} (TiAl) phases. The TiAl{sub 3} reaction layer, however, did not transform to a lamellar structure but only to a single-phase {gamma}. Joint strength at room temperature and at 873 K exhibited about 220 MPa which was about the same as that of the base metal. (orig.)