Development of new metallic alloys and compounds
This RAD deals with the sample preparation and characterization. In order to have a rational approach to this activity, a detailed study of the phase diagram and thermodynamics is of course mandatory. This is carried out experimentally, but also using simulations either semi-phenomenological such as CALPHAD, or using ab-initio based approaches. Single phase and single crystal preparation is of prime importance to analyze the crystal structure and have a good understanding of the structure/property relationship. The structural analysis needs to be fully detailed and in particular includes the analysis of disorder, which plays an important role in CMA. Simulation is often a tool to better understand and determine this disorder and phase stability.
The network has gained an internationally renowned expertise in this field and several systems have been studied with large single grain growth, which constitutes a material reference basis within the European Integrated Center: Al-based CMA (Al-Cu-Co, Al-Ni-Co, Al-Ni-Fe-Co) Zn-Mg tetrahedral close-packed phases (Zn-Mg, Al-Zn-Mg, see Figure 1), Mg-based light alloys, Laves phases, RE-Cu phases, Ge-based clathrates, skutterudites both for thermoelectric material, Gd-Si-Ge as magnetocaloric material, Zn-Sb and Cd-Sb for their structural transitions [1-4].
Figure 1: The ternary Al-Zn-Mg phase diagram, investigated experimentally and by simulations and the single crystal of the quasicrystalline t2 phase.
Almost all partners are participating in this RAD.
For the following years the main objectives are two-fold:
(i) Develop basic research, with as long term target the design of new compounds assisted by simulations. Indeed simulations have been progressing a lot in recent years, and it is now feasible to predict the stability and structure of complex phases. Developing further such tools is thus of prime importance
(ii) Materials preparation for specific needs (for instance thermo-electrics, composites …) and thus a strong interaction with other RAD.
1. S. Gottlieb-Schönmeyer, S. Brühne , F. Ritter , W. Assmus, S. Balanetskyy, M. Feuerbacher, T. Weber, W. Steurer, Crystal growth of copper-rich ytterbium compounds: The predicted giant unit cell structures YbCu4.4 and YbCu4.25, Intermetallics, 2009, 18, 6-10
2. Feuerbacher M, Thomas C, Roitsch S, Single-crystal growth of the complex metallic alloy phase Mg32(Al,Zn)49 Intermetallics, 2008, 16, 943-947
3. Gille P, Bauer B Single crystal growth of Al13Co4 and Al13Fe4 from Al-rich solutions by the Czochralski method, Crystal Research and Technology, 43, no.11, 2008, pp. 1161-7.
4. Kerkau A. Gruner D. Ormeci A. Prots Y. Borrmann H. Schnelle W. Bischoff E. Grin Y. Kreiner G., Site occupation reversal in the C14 Laves Phase Nb(Cr1-xCox)2 Zeitschrift fur Anorganische und Allgemeine Chemie, 635, 2009, pp. 637-48