In and ex situ investigations of the β-phase in a Nb and Mo containing γ-TiAl based alloy

In beta-stabilized Ti-43Al-4Nb-1Mo-0.1B alloy (composition in atomic percent) the correlation between the occurrence of beta-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 beta-phase with temperature. Thermodynamic calculations based on the CALPHAD method were applied to correlate the phases developed in the beta-solidifying TiAl based alloy under investigation. This alloy is characterized by an adjustable beta-phase volume fraction at temperatures where hot-work processes such as forging and rolling are conducted. Due to a high volume fraction of beta-phase at elevated temperatures the hot-extruded alloy can be forged under near conventional conditions. (C) 2008 Elsevier Ltd. All rights reserved.