engleski

The transport properties of the phase beta-Mg2Al3

The beta phases in the magnesium.aluminium (the name commonly used beta-Al3Mg2) system belongs to a huge group of largely unknown multinary alloys named 'complex metallic alloys'. In these alloys, phases are formed with crystal structures based on giant unit cells containing many tens, up to more than a thousand atoms per unit cell. This contrasts with conventional alloys whose crystal unit cells in general comprise a few atoms only. Within the huge unit cells, the atoms are arranged in clusters. These clusters strongly influence the electronic structure and the lattice dynamics. As a result, these materials offer unique combinations of properties, which are mutually excluded in conventional materials. Among the still relatively small number of known complex metallic alloys, large crystals of the orthorhombic beta-Al3Mg2, with the enormous number of 1168 atoms per unit cell, were grown recently. Here we present the first study of their transport properties (electrical resistivity, thermopower and thermal conductivity). The results, that are in many respects different from both regular, periodic metals and alloys and quasicrystals indicate that the transport properties of the beta-Al3Mg2 are affected by both the quasiperiodic short-range atomic order and the long-range periodic order.

complex metallic alloys; electrical resistivity; thermopower; thermal conductivity

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