The feasibility of producing TiAl and other titanium-aluminide compounds by reacting Al with TiCl4 has been explored. This process is similar to the well known Kroll and Hunter processes for producing pure Ti. The chemical reaction for the formation of TiAl from TiCl4 and Al is as follows: 3 TiCl4 + 7Al --> 3 TiAl + 4AlCl(3) Based on available thermodynamic data, calculations revealed this reaction is energetically favored above 600 degrees C. At lower temperatures TiCl4 is on ly partially reduced to TiCl2 and AI,TI. Experiments, utilizing a fluidized bed reactor, were used to react Al powder with TiCl4, at either 600 and 740 degrees C, and the resultant powder was characterized by X-ray diffraction. At 600 degrees C the powders transformed to AI,Ti and Al5Ti2. At 740 degrees C, the product was dependent on the size of the initial AI powder in the bed. Small Al powders (<100 mu m) transformed to a combination of Ti3Al and TiAl, where as, larger powders transformed to Al3Ti and TiAl. The results demonstrate that it is possible to produce aluminides by reducing TiCl4 with Al; however, to produce a uniform reaction product, such as single phase TiAl, precise control over the reaction conditions is required.
