Homogeneous dispersion of TiC nano particles in a cast carbon steel matrix

Metal matrix nano-composites (MMNCs) (metal matrix with nano-sized ceramic particles) can be of great significance because of their high performance and thus it would be advantageous to produce as-cast bulk MMNCs. However, it is so difficult to disperse nano-sized ceramic particles uniformly in molten metal. In this study, carbon steel matrix composites with a homogeneous dispersion of TiC nano particles were fabricated by conventional liquid metal casting method. In order to get highly wettable nano-sized TiC ceramic particles, the micro-sized (approximately 10 m) TiC particles were first mechanically milled (MMed) by Cu in a high-energy ball mill machine (MMed TiC/Cu), and then mixed with Sn powders to obtain better wettability, as this lowered the surface tension of the carbon steel melt. According to OM images, an addition of MMed TiC/Cu-Sn mixed powders favorably disperses the TiC nano particles in the carbon steel matrix. SEM and EDS images revealed that spherical particles with several hundreds of nanometers were distributed uniformly in the carbon steel matrix. It was also found that the grain size refinement of the cast matrix is achieved remarkably when TiC nano particles were added due to the fact that TiC nano particles act as nucleation sites during the solidification process.