In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering

Fe alloy composites reinforced with in-situ titanium carbide (TiC) particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8, 0.9, 1 and 1.1 to investigate the microstructure and mechanical properties of in-situ TiC/Fe alloy composites. The microstructure showed that the in-situ synthesized TiC particles were spherical with a size of 1-3 mu m, irrespective of C/Ti ratio. The stoichiometry of in-situ TiC increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9, but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in TiCx at the common sintering temperature. The in-situ TiC/Fe alloy composite with C/Ti = 0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon (C/Ti =1 and 1.1) resulted in unreacted carbon within the Fe alloy matrix, while insufficient carbon (C/Ti = 0.8) caused the depletion of carbon from the Fe alloy matrix, leading to a significant decrease in hardness. This study presents that the maximized hardness and superior strength of in-situ TiC/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized TiC particles, while maintaining the ductility of the composites, compared to those of the unreinforced Fe alloy. Therefore, we anticipate that the in-situ synthesized TiC/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool, mold and roller material applications. (C) 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.