Titanium silicide (Ti5Si3) synthesis under shock loading

Ti-Si binary system shows exothermic reactions during the formation of several line compounds, which can be used for self-propagating high temperature synthesis (SHS) of starting powders. In this research, titanium silicide (Ti5Si3) was synthesized from high purity Ti and Si powders using shock waves in a 10 cm diameter and 14 m long gas gun. Influences of compact density, shock velocity, milling time and filler concentrations were studied. Mullite was used as an inert ceramic filler in different wt.% and mixed with ball-milled powders. Phase analysis, microstructural analysis and microhardness measurements were done on samples that were recovered after shock loading. Results indicate that powders with a lower compact density generated higher temperatures during shock consolidation. The change in velocity generated different compressive stresses in Cu target ranging 4.4-8.6 GPa, and found to have a significant effect on the reaction kinetics. Both increasing filler material amount and decreasing milling time reduced the reaction kinetics. Though the presence of mullite decreased the reaction kinetics, it also reduced residual porosity in the compacts via forming an in situ intermetallic-ceramic composite. (c) 2006 Elsevier B.V. All rights reserved.