1. Introduction: Few studies have formerly focused on mechanism and kinetics of Ti-Al diffusion couples and the reported kinetic exponents and activation energies vary widely among different works. In this work, a simple diffusion couple of titanium and aluminum was prepared to clarify the kinetics of TiAl3 formation and growth. 2. Experimental Procedure: One pure aluminum foil (250 m thick) and two pure titanium sheets (1 mm thick) were used in a form of tri-layer sandwich providing a simple diffusion couple. Heat treatments were carried out at 600 and 650 °C (±1 °C) using a tube furnace with an argon atmosphere. EPMA characterization was employed to determine the concentration distributions of Ti and Al across the compound layer. 3. Results: Fig. 1 shows that compound layer thickness increases by increasing the temperature and time. According to EPMA results, the intermetallic layer had a composition of Al–25 at.% Ti which corresponds to TiAl3, however, titanium concentration was slightly decreasing from Ti-TiAl3 interface to TiAl3-Al interface. Assuming that TiAl3 growth is dominantly controlled by aluminum diffusion through the compound layer, the impurity diffusion coefficient of aluminum in the TiAl3 layer was calculated to be equal to 4.50×10-12 m2s-1. Furthermore, activation energy of 47.96 kJ/mol was estimated for TiAl3 layer formation and growth according to parabolic nature of diffusive growth of TiAl3.

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