ANALYSIS OF GROWTH MECHANISM OF DENDRITIC TITANIUM CARBIDES PRODUCED BY LASER ALLOYING OF PURE TITANIUM WITH GRAPHITE POWDER

The microstructure of dendritic titanium carbides fabricated by laser surface alloying of pure titanium with graphite powder is investigated using electron probe microanalyzer (EPMA) and high-resolution transmission electron microscope (HRTEM). The growth mechanism of TiC crystals is that crystal grows by the model of continuous growth at the beginning of solidification and then the crystal surfaces that are suited to lateral growth develop fully by the model of spiral growth. So, the final morphology of dendritic TiC looks like it is composed of tiny crystal grains in a linear arrangement.