A proper understanding of thermodynamic stability of individual phases is a basic prerequisite for the research and design of new advanced materials. This is especially true when the desired material properties are achieved by creating a suitable combination of multiple phases in the alloy. Employees of the Department of Structural and Phase Analysis are engaged in the study of phase stability both with the help of experimental methods and with the use of computer modeling.
In particular, we focus, for example, on the study of alloys in the Al-Mg-Ge-Sn system. Aluminum-based alloys, especially in combination with silicon and copper, are currently intensively studied because they exhibit a combination of suitable material properties such as good castability, low density, high specific strength, and toughness, as well as very good corrosion resistance. This makes them to be used mainly in the automotive and aviation industries. Further improvement of the properties can be achieved by adding other alloying elements such as Mg, Ge, and Sn. Alloying elements can influence the precipitation process in Al-Si-(Cu) alloys and thus play a fundamental role in microstructure modification of the material. The aim of our research is to determine the structure and chemical composition of the emerging intermetallic phases in partial binary and ternary systems, for different temperatures. The obtained data then will be used to create a new generation of thermodynamic database for the CALPHAD (CALculation of PHAse Diagram) method, which is used for simulating phase diagrams of multi-component systems and can predict precisely the influence of doping elements. This research is carried out in cooperation with the Institute of Materials Science and Engineering of the Academy of Sciences of the Czech Republic in Brno.
Another example of our research can be nanostructured alloys for biomedical applications based on immiscible systems. For these materials based on two mutually immiscible elements, the desired properties are achieved by the precipitation of nanoparticles, which is ensured by appropriate heat treatment or advanced preparation technologies such as powder metallurgy.
From the theoretical approaches, quantum-mechanical calculations based on density functional theory are used for computer modeling in addition to the already mentioned CALPHAD methods. These methods can predict the thermodynamic stability of individual phases without the use of experimental data. In combination with machine learning or the Monte Carlo method, it is then possible to accurately simulate relatively complex systems.
Contact person:
Martin Zelený, dr.