Growth Elements and Growth Habit of Coordination Polyhedrons of TiC Crystal in Titanium Alloy

The shape of TiC can be octahedral, facet or/and non-facet dendrite in as-cast Titanium alloys. The growth element and growth habit of TiC6 in titanium alloys were analyzed with the theory of coordination polyhedron through directionally solidified samples. The results indicate that the growth elements of TiC are TiC6 with six coordinations. During the stacking of TiC6 growth element, the growth rates of families {100} and {111} are different, which may easily result in potential.nuclei of octahedral TiC surrounded by {111}. During the growing of TiC in the melt, the undercooling and composition at different part of the crystal's surface vary significantly. Some quadratic dendrites may appear in the direction of 100nd are characterized by facet growth resulting in facet dendritic TiC finally. If a large amount of defects such as screw dislocation are formed on the slowly growing surface of TiC during the growth, the facet will disappear and non-facet dendritic TiC will form.