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M: Metallphysik

M 20: Symposium on Structurally Complex Alloy Phases II (SCAP II)

M 20.2: Vortrag

Donnerstag, 14. März 2002, 11:30–12:00, H16

COMPLEX INTERMETALLICS, A NEW SPRING BOARD IN MATERIALS SCIENCE — •Jean-Marie DUBOIS — LSG2M, Ecole des Mines, Parc de Saurupt, F-54042 Nancy

Among complex intermetallics, the families of compounds that contain a quasicrystal are of special interest. In such families (for instance the Al-Cu-Fe system), the quasicrystal is surrounded by so-called approximant crystals, which exhibit a very similar local order than the quasicrystal itself, yet showing also periodicity. Because periodicity is a weak property in such compounds, physical, or mechanical, properties more or less resemble those of the genuine quasicrystal. Yet, in more remote areas of the phase diagram are found normal crystals, hence with quite different properties.

The new spring board that complex intermetallics offer to metal physicists and material scientists is able to help them understand in great detail what is the physical reality hidden behind the loosely defined expression No-dqmore or less resemblingNo-dq that was used above. As it happens, understanding this concept when looking upon an entire family of compounds like the one encountered in Al-Cu-Fe alloys leads to a better understanding of generic properties such as optical conduction in complex metallic systems, or wetting at the surface of oxidised metals.

The talk will put emphasis on these two examples with a view at using selected complex intermetallics as model systems for a deeper understanding of properties that are of technological relevance.