Formation of Ti5Si3 and V5Si3 by self-propagating high-temperature synthesis and evaluation of combustion wave kinetics

Fabrication of Ti5Si3 and V5Si3 was conducted by self-propagating high-temperature synthesis (SHS) from the elemental powder compacts of their stoichiometries. Combustion wave kinetics was experimentally studied by measuring the combustion front velocity and temperature, and numerically investigated to determine the Arrhenius factor of the rate function (K-0) and to evaluate the effective thermal conductivity (k(eff)). Experimental results showed that the 5Ti + 3Si reaction is more exothermic than the 5V + 3Si reaction. With the increase of sample density from 50% to 60% TMD, the flame-front velocity increased from 28 to 50 mm/s for the formation of Ti5Si3 and from 6.9 to 8.5 mm/s for V5Si3. Based upon numerical simulation and experimental validation, K-0 = 3 x 10(9) s(-1) and 5 x 10(7) s(-1) were deduced for combustion synthesis of Ti5Si3 and V5Si3, respectively. The ratio of keff/kbulk increasing from 0.02 to 0.05 was employed in the numerical calculations to simulate the effect of sample compaction density on combustion wave kinetics. Moreover, the measured and calculated combustion front temperatures were comparable, which confirmed the reaction exothermicity of the numerical model. (C) 2017 Elsevier B. V. All rights reserved.