a b s t r a c tIn a b-stabilized Ti-43Al-4Nb-1Mo-0.1B alloy (composition in atomic percent) the correlation between the occurrence of b-phase and temperature was analyzed experimentally and compared to thermodynamic calculations. Results from in situ high-energy X-ray diffraction, texture measurements, heat treatments, scanning electron microscopy, and temperature-dependent flow stress measurements were used to study the evolution of the b-phase with temperature. Thermodynamic calculations based on the CALPHAD method were applied to correlate the phases developed in the b-solidifying TiAl based alloy under investigation. This alloy is characterized by an adjustable b-phase volume fraction at temperatures where hot-work processes such as forging and rolling are conducted. Due to a high volume fraction of bphase at elevated temperatures the hot-extruded alloy can be forged under near conventional conditions.

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Solid-state phase transformations and phase transition temperatures in Ti-45 at.% Al and Ti-45 at.% Al-(5, 7.5, 10) at.% Nb alloys were analyzed experimentally and compared to thermodynamic calculations. Results from scanning electron microscopy, high-energy and conventional X-ray diffraction as well as differential scanning calorimetry were used for the characterization of the prevailing phases and phase transformations. For the prediction of phase stabilities and phase transition temperatures, thermodynamic calculations using the CALPHAD method were conducted. In order to achieve better agreement between calculated and experimental results, a commercially available database was modified using our own results from thermo-physical measurements and annealing treatments.

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