Combustion synthesis of TiC- high entropy alloy CoCrFeNiMn composites from granular mixtures

Abstract

The advantage of combustion synthesis is the ability to produce composites from powders in a single technological step, using the heat of an exothermic reaction, in a fast and energy-efficient manner. Ceramic-metal composites TiC–High-Entropy Alloy (HEA) CoCrFeNiMn were fabricated by combustion synthesis from granular mixtures. The content of the metal binder components varied from 10 to 30 wt% and the combustion velocity and temperature gradually decreased as the binder content increased. Scaling up synthesis requires clarification of the parametric range for implementing a safe combustion mode. The impurity gas content and the range of safe conductive combustion were determined from known theoretical models and experimental combustion velocities of samples of granules of 0.6 and 1.1 mm size. The main phases of the product were titanium carbide with up to 3 at. % Cr and HEA CrCoFeNiMn with a reduced Mn content compared to the equimolar composition. The content of secondary phases Cr7C3 and carbon did not exceed 5 wt%. The use of granular mixtures solved the problem of significant sintering of exothermic powder mixtures containing metal binder during combustion. After synthesis, the granules retain their size and do not sinter together, making it easy to grind the sample and obtain a TiC-HEA composite powder.