Formation of Ti-Aluminides on Commercially Pure Ti via the Hot-Dipping Aluminizing Process

This study examined the applicability of the hot-dipping aluminizing technique carried out on commercially pure titanium (Ti) as a new method for the formation of Ti-aluminides on a Ti surface. The process was carried out using pure aluminum (Al) and Al 7075 alloy in molten Al baths at 900 °C and 1000 °C for 4 h and 6 h, respectively. The microstructure, phase fraction, and composition analysis of the formed layers were examined using field emission scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. Three different areas with different thicknesses were formed on the Ti surface by the hot-dipping aluminizing technique. The top (Al coating) layer consisted of Ti and Al elements having a higher hardness than the base metal. The second layer, formed below the Al coating, was the Ti–Al layer having the highest hardness on the surface. Below this layer the Al was diffused. As a result of the Ti aluminizing process carried out at different temperatures and durations in this study, TiAl, TiAl2, TiAl3, and Ti3Al phases were obtained. These phases positively affected the mechanical and corrosion properties.