Solidification microstructure and mechanical properties of B1-type TiC in Fe-Ti-C ternary alloys

The microstructure of the B1-type TiC formed during solidification and its mechanical properties were investigated using arc-melted Fe–Ti–C ternary alloys. The TiC formed at relatively high temperatures in the liquid as the primary phase exhibited a dendritic shape. With decreasing temperature and/or decreasing Ti and C content in the liquid, the morphology of the TiC changed to a cubic shape with a {001}TiC habit plane, a plate shape with a {011}TiC habit plane, and a needle shape with a preferential growth direction of <001>TiC. The morphology of the TiC was characterized by the anisotropy of its surface energy and its growth rate. The cubic shape with a {001}TiC habit plane was formed as a result of the {001}TiC surface exhibiting the lowest surface energy among the TiC surfaces. However, the plate shape with a {011}TiC habit plane and the needle shape with a <001>TiC preferential growth direction likely formed because the slowest and fastest growth rates corresponded to the <011>TiC and <001>TiC directions, respectively. At room temperature, the alloy with dendritic TiC was fractured in the elastic deformation region because TiC exhibited no plastic deformation. However, the results obtained at 800°C suggested that the TiC exhibited plastic deformability and that the alloy with the dendritic TiC was also plastically deformed.