Study of gasless combustion products of Ti – Si – Al powder mixtures

The combustion synthesis products in titanium, silicon and aluminum powder mixtures under the wave mode combustion are investigated by X-ray diffraction analysis and optical metallography. The synthesis products contain titanium silicide Ti5Si3 and titanium aluminide TiAl3, the ratio of which depends on the content of aluminum powder in the reaction mixtures. The combustion temperature of the mixtures decreases with an increase in the aluminum content. This is a consequence of the substitution of titanium aluminide in the synthesis products for titanium silicide, which has a multiple negative formation enthalpy compared to that of the silicide. Using ideas about the features of the growth of silicide and aluminide nuclei in a liquid metal solution, the effect of the combustion temperature on the dispersion of the structure of the synthesis products is discussed.