Phase transitions and compression properties of Ti2AlC/TiAl composites fabricated by combustion synthesis reaction

The phase transitions in the Ti-Al and the Ti-Al-C systems are investigated by the differential thermal analysis (DTA) and X-ray diffraction (XRD). The results reveal that the addition of C not only leads to the formation of the Ti2AlC phase but also lowers the formation temperatures of the TiAl and Ti3Al phases. In the both systems, the combustion synthesis reactions are ignited at the melting point of Al, so the TiAl alloy and the Ti2AlC/TiAl composites are successfully fabricated at a lower temperature (about 660 degrees C) with an applied pressure. The yield strength, the ultimate compression strength and the work hardening rate of the Ti2AlC/TiAl composites are all higher than those of the TiAl alloy and increase with the increase in the Ti2AlC content. The average ultimate compression strength of the 6 vol.% Ti2AlC/TiAl composite is 179 MPa higher than that of the TiAl alloy without sacrificing ductility. (C) 2012 Elsevier B.V. All rights reserved.