EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The capability of Ti-Al-based alloys to substitute Ni-based superalloys in high-temperature, high-strength applications has led to intensive research over the last decades. Today, such alloys based on the intermetallic phases TiAl and Ti3Al with some additions of, e.g., Cr, Nb, or Mo, have made the step into real applications for example as turbine blades. Regarding the production of parts from this type of material, there is still a need to improve the high-temperature deformability without reducing its strength at application temperature. By adding Mo and W, so-called β-stabilizers, the cubic (βTi) phase is stabilized to higher Al contents than in the binary Ti-Al system at typical manufacturing temperatures (1200°C), which improves the hot working capabilities significantly. Therefore, the phase relations especially at temperatures above 1000°C play an important role in the development of next-generation TiAl-based alloys. The literature data of phase equilibria above 1000°C are often contradicting (Ti–Al–Mo) or very limited (Ti–Al–W) even though a lot of research has been done. The results presented here aim to contribute to the clarification of such high-temperature phase equilibria in both alloy systems. The research is carried out within the scope of the CleanSky 2 EU-project ADVANCE, which has the goal to improve an existing CALPHAD database of related materials systems and to speed up the development of next-generation TiAl-based alloys.