Even today, there is still little known about a large number of promising but more complex materials. These include intermetallic phases such as the topologically close-packed (TCP) phases that are especially interesting for high-temperature applications because of their high melting points and high strength even at elevated temperatures. However, due to the complex crystal structure of TCP phases and the resulting brittleness, our knowledge of their plasticity and therefore their applicability is still limited.

This is about to change, as small-scale mechanical experiments allow us to investigate plasticity even in the most brittle materials. Here, we consider the binary Fe-Ta as well as the ternary Fe-Ta-Al system, both containing a C14 Laves and a µ-phase. These systems are very interesting since the structure of the Laves phase is also contained as an intergrown unit in the µ-phase. The building block-like structure allows a systematic investigation of the plasticity of these TCP phases as well as a transfer of the findings to other complex crystals.

The preparation of the samples using an arc melter allows stoichiometric and non-stoichiometric compositions to be investigated. Tests such as nanoindentation and micropillar compression tests not only provide information about the mechanical properties but also about the activated slip systems. Understanding the underlying dislocation mechanisms is achieved by TEM investigations. Through this research, the influence of the crystal structure and chemical composition on the mechanical properties and the deformation mechanisms of the TCP phases in the Fe-Ta(-Al) system are studied.