Titanium–aluminum diffusion couples were prepared using pure titanium and aluminum sheets in the form of a tri-layer sandwich. The Ti–Al interface was investigated after heating the specimens at 550, 575, 600, 625, 640 and 650 °C. EPMA results indicated that TiAl3 intermetallic layer is the only phase that can form and grow at the Ti–Al interface. Evidences from the SEM observations showed that aluminum is the dominant diffusing component through the TiAl3 layer which reacts with titanium at the Ti–TiAl3 interface. According to the normal parabolic behavior of the layer thickening, activation energies of 33.1 kJ mol−1 and 296.2 kJ mol−1 were calculated for the low temperature grain boundary diffusion controlled growth and the high temperature bulk diffusion controlled growth, respectively. Overall activation energy of 76.8 kJ mol−1 is calculated for the diffusion-controlled growth of the TiAl3 layer at all applied annealing temperatures.

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