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MM: Fachverband Metall- und Materialphysik

MM 5: Materials Design I

MM 5.6: Vortrag

Montag, 23. März 2009, 11:30–11:45, IFW D

Theoretical multi-physics approaches to solid-solution strengthening of Al — •Duancheng Ma, Martin Friák, Dierk Raabe, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, 402 37, Düsseldorf, Germany

The strengthening of soft metallic materials has a long tradition and is an important metallurgical topic since the time when ancient smiths forged the first swords. Intense materials research revealed a combination of three mechanisms as decisive for solid-solution strengthening phenomena: (i) the size mismatch of components (Mott and Nabarro’s parelastic concept [1]), (ii) the elastic modulus mismatch of atoms (Fleischer’s dielastic contribution [2]), and (iii) the concentration of solutes (statistical concept of Friedel [3] and Labusch [4]). Combining density functional theory calculations and linear-elasticity theory, the key parameters that are essential for the classical strengthening theories are determined in order to test them and identify their possible validity limits. The strengthening of fcc aluminium is chosen as an example and a series of binary systems Al-X (with X = Ca, Sr, Ir, Li, Mg, Cu) was considered. Comparing our results with those obtained by applying classical theories we find clear deviations. These deviations originate from non-classical lattice distortions due to the size mismatch of solute atoms in their first coordination shells.

1. N. F. Mott and F. R. N. Nabarro, Proc. Phys. Soc. 52, 86 (1940).

2. R. L. Fleischer, Acta. Metall. 9, 996 (1961).

3. J. Friedel, Dislocations (1964).

4. R. Labusch, Phys. Stat. Sol. 41, 659 (1970).