Formation and microstructure of (Ti, V)C-reinforeed iron-matrix composites using self-propagating high-temperature synthesis

The combustion synthesis of (Ti, V)C-reinforced iron-matrix composites from elemental powders was examined. Examination using scanning electron microscopy indicated that two types of carbide particles were formed having a different size and composition from each other. These were sub-micron size (Ti, V)C particles and pure TiC or TiC-rich particles of a slightly larger particle size. The development of the microstructure and formation of the two types of carbides were explained through an understanding of the reaction mechanism and the thermodynamics of the carbide phases. Increasing the amount of vanadium in the reactants led to a decrease in the carbide and the iron grain size and to a corresponding increase in microhardness.