Especially, tight emission reduction targets, triggered by an increasing global ecological awareness, as directed by national and international initiatives and legislation, have become a major driving force in the development of this alloy class.

Due to these properties, TiAl alloys are particularly suitable for rotating components of modern propulsion systems, such as turbine blades of aero engines and turbocharger wheels of automotive engines. Intermetallic titanium aluminides belong to the most promising materials to meet today’s most prevalent demands for structural high-temperature materials of combining high strength with low density (next to other important characteristics like high creep and oxidation resistance as well as high modulus and strength retention at elevated temperatures). This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys. Atom probe tomography (APT) offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development.

Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density.

Download Wallgram - Awesome W