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Examinations with the atom probe are an excellent way to analyze all phases of a material on an atomic level, thus enabling a better understanding of their formation. This study aims to provide an appropriate method for the preparation of atom probe specimens made of multiphase intermetallic titanium aluminide alloys. With the help of a focused ion beam system and transmission kikuchi diffraction, tips of defined phases and phase interfaces were prepared, as is shown by the example of the ωo-Ti4Al3Nb phase, which is precipitated from the βo phase. The chemical composition of the two phases was determined by subsequent atom probe measurements which allowed to draw conclusions about the phase formation.

The distribution of alloying elements in the constituent phases of a C-containing γ-TiAl based alloy has been characterized locally by atom probe tomography. The major elements of the alloy under consideration -Ti, Al, Nb, and Mo -are distributed uniformly within each of the constituent phases. Furthermore, Mo is preferentially dissolved in the β o -phase, whereas Nb content is similar in all phases. The selected C concentration of the alloy is below the overall solubility limit as no precipitates have been observed. Therefore, C is enriched in the α 2 -phase, whereas the β o -phase is depleted of C. In addition, β o /γ-interfaces have been prepared by site specific sample preparation and characterized by atom probe tomography. Segregation of Mo and C into the interfaces and their close vicinity was observed.