Production of γ-TiAl based alloy by combustion synthesis + compaction route, characterization and application

Synthesis and densification of γ-TiAl alloy with nominal chemical composition Ti-48A1-2Cr-2Nb (at.%) have been investigated. The alloy is prepared in one step using a combustion synthesis + compaction process, where the synthesis and the shaping take place at the same time. Two different combustion routes are used: Forced Self-propagating High-temperature Synthesis + Compaction (FSHS + C) and Thermal Explosion + Compaction (TE + C). The optimal synthesis parameters such as ignition point, load application delay time, load value, load holding time, heating and cooling rates are determined. After the processing, the density of the samples was measured to be of about 99 % of the theoretical value. It is shown that the oxygen content can be controlled during the processing and products with the same or lower oxygen content than that in the original raw material can be obtained. Analysis of chemical composition and microstructure shows that a complete chemical homogenization, required phase composition, desired lamellar microstructure and relaxation of possible internal stresses require additional thermal treatment of samples prepared by both FSHS + C and TE + C processes.