The development of new lightweight materials is crucial for numerous energy-conversion applications in the automotive and aerospace industries. Low-cost and low-density materials operating at higher temperatures ensure a lower fuel consumption and environmentally cleaner and more efficiently produced electricity. Two basic options in materials design and/or functional optimization are the selection of an appropriate chemical composition and the processing of an optimized microstructure. Both characteristics are mutually interlinked and inherently multiscale in nature what make them challenging to study.

We address these fundamental aspects to a promising class of lightweight intermetallics: Fe3Al-based alloys exhibiting an excellent high temperature oxidation and sulfidation resistance up to 1000 °C. Therefore, they possess a high potential as a low cost alternative to conventional ferritic, martensitic or austenitic steels [1]. For actual applications as structural materials, however, further improvements of these alloys e.g. via compositional optimization are considered. Specifically, these optimizations should lead to enhanced mechanical properties, such as improved room temperature ductility, or higher strength and creep resistance at temperatures above 600°C. For this, a detailed knowledge of the influence of alloying elements on the physical and mechanical properties is crucial but literature data are hardly available and the experimental determination is very time consuming. The use of new multidisciplinary approaches combining both experimental and theoretical methods is thus very desirable as it promises a remarkable reduction of the experimental effort and corresponding costs.

Theoretical ab initio calculations based on fundamental quantum-mechanical laws, solely from the knowledge of the atomic composition and/or structure, are nowadays increasingly used [2, 3] to accurately predict material properties without any empirical input. Basic mechanical and physical properties, like crystal structure and single crystal elastic constants, can be reliably calculated at zero temperature using density functional theory (DFT) [4, 5]. The calculated materials characteristics gathered at the atomistic level and our deeper understanding of the underlying processes can be effectively combined with advanced experimental techniques in order to design new materials with desired properties.

In our study, the site preference of the alloying elements and changes in the Young’s modulus are theoretically determined. The ab initio calculations are performed for T=0K conditions but the qualitative validity of the predicted metallurgical trends can be extended also to finite temperature.

The theoretical research is complemented with measurements of the Young’s modulus at 77 K and continuously from 293 K to 1273 K, i.e., in the relevant temperature range of possible applications of Fe3Al-based alloys by means of the impulse excitation method (see Fig. 1). Both the calculations and measurements are performed for a selected group of substituents exhibiting the solubility in Fe3Al at least as high as 2 at.%.