Original Scientific Paper Heat Conduction in Complex Metallic Alloys*

Abstract. Thermal conductivity, κ, of ε-phase Al73Pd25Fe2 and "Bergman phase " Mg-Al-Zn is presented, which resembles the features common to all complex metallic alloys: relatively low value, shallow local maximum or change of slope at approximately 50 K, and a rise above 100 K. The electron contribution, κel, is calculated using Wiedemann-Franz law, while the calculation of the phonon thermal conductivity, κph, below 50 K is calculated employing Debye model. The sum of the two does not explain the experi-mental data at higher temperatures (above 100 K). This discrepancy is analyzed in three competitive ways: assuming an increase of an effective Lorenz number, taking into account the hopping of localized lattice vibrations, and employing a "bipolar diffusion effect", known from the theory of semiconductors. While the results of the former two approaches confirm other findings in literature, "bipolar diffusion effect " needs to be adopted for the specific electron structure of complex metallic alloys