Structure and Phase Composition of Ti–Al–Si Powder Composites at Different Synthesis Conditions

The paper presents the structure and phase composition of Ti−Al−Si powder composites produced in different conditions, which include vacuum sintering and self-propagating high-temperature synthesis (SHS). The certain ratios of reactive components are used in experiments for the formation of two-phase composites, matching the TiAl3 + Ti5Si3 and Ti3Al + Ti5Si3 compositions. The vacuum sintering of Ti−Al−Si powder composites provides mostly the formation of the two-phase structure, but the quantitative ratio of the appeared phases can considerably differ from the calculated compositions. The lattice parameters in these phases are rather distorted. The analysis of the synthesis in the wave mode combustion of Ti−Al−Si powder composites shows that the synthesis completes only in the TiAl3 + Ti5Si3 composite. This allows us to prepare the powder from the synthesized product. The paper analyzes the behavior of the synthesized powder based on the phase composition of the TiAl3 + Ti5Si3 composite after the vacuum sintering of the powder compacts. It is found that after the 1300°C vacuum sintering of the SHS products based on the TiAl3 + Ti5Si3 composite, its qualitative phase composition remains with a small change in the quantitative phase composition. The compaction of the SHS products is observed together with the reduction in the residual porosity.