With the aim of producing intermetallic composites for high-temperature structural applications, Ti–Al–Si alloys were prepared by mechanical alloying of elemental powder blends. The compositions were chosen to form intermetallic composites consisting of α 2-Ti 3Al, γ-TiAl and Ti 5Si 3 intermetallic compounds in the equilibrium state. The alloys were characterized by X-ray diffraction and differential scanning calorimetry. The metastable phases prepared after milling decompose by a two-step process upon annealing. Thereby four intermetallic metastable phases are formed in the composition range investigated. From the results of the phase analysis, partial Ti–Al–Si phase diagrams for the as-milled state, the intermediate states and the final state are derived. The stability of the composite microstructure is investigated by X-ray diffraction and transmission electron microscopy.