FABRICATION OF TI2ALC/TIAL COMPOSITES USING COMBUSTION REACTION PROCESS

The potential of TiAl as an elevated temperature material is well investigated. However, negligible low-temperature ductility and toughness and low high-temperature strength have limited its practical applications. To improve these properties, this compound was made as a composite material containing a second phase such as Ti2AlC. In the present study, using elemental powders, combustion reaction was carried out to form intermetallic/ceramic composites in the Ti-Al-C system. As a result, the compact of Ti and Al powders with C powder reacted exothermically to form TiAl and Ti2AlC with a small amount of Ti3Al, and the mixture products had a fine distribution of the Ti2AlC particles in the matrix TiAl, and the volume fraction of the Ti2AlC particles depended on the amount of C present. Subsequently, using these reacted products, button ingots were arc-melted to a full density. The resulting Ti2AlC particles were ellipsoidal or columnar in shape with sizes from 5-15-mu-m and appeared to be homogeneously distributed. It was found that the composite materials produced have a good toughness and strength at both room and elevated temperatures. Consequently, present investigations have considerable interest as a new combustion reaction process to make a composite material.