Contribution:

Title:

Intermetallic TiAl based alloys – from fundamental research to application

Abstract:

Intermetallic TiAl alloys based on the γ-TiAl phase are already used as engineering lightweight high-temperature materials in aircraft and automotive engines. Thereby, they partly substitute the twice as heavy Ni-base superalloys. Present applications are, for example, blades in the low-pressure turbine of advanced aero-engines, turbine wheels for turbocharger systems of car diesel engines and engine parts used in racing sport applications. All the applications mentioned above require balanced mechanical properties, i.e. sufficient ductility at room temperature as well as high creep strength at elevated temperatures. In the framework of this presentation the alloy design strategies, which have been applied for the development of so-called process adapted TiAl alloys will be explained. Besides the considerations which have led to the selected alloying elements, the heat treatments conducted subsequent to conventional hot-forging and additive manufacturing are discussed. In this context it will be shown that a combination of computer-aided alloy design and novel characterization techniques, e.g. in-situ high-energy X-ray and neutron diffraction, has accelerated both alloy and process development as well as the understanding of this class of alloys sustainably. This plenary talk, however, is not only addressed to the TiAl scientific community, because the presented theoretical and experimental aspects and ideas can be adopted to multitude of material systems and technology developments.