Thermophysical properties of FeAl (Fe-40 at.%Al)

The thermophysical properties — electrical resistivity, thermal conductivity, thermal expansion, and specific heat, of a B2 iron-aluminide (Fe-40 at.% Al) alloy are measured. The measured values of electrical resistivity indicate three distinct regions. An initial sharp rise below 400°C is followed by a gradual increase to near saturation around 900°C. Resistivity above this temperature exhibits an anomalous negative temperature dependence. The thermal conductivity displays a continuous rise as a function of temperature for T<800°C, beyond which it saturates to a value of ∼0.17 W/cm-°C. The relation between electrical resistivity and thermal conductivity obeys the Wiedemann-Franz law signifying the dominance of electrons in the heat transport. The measurements of specific heat indicate a complex behavior suggesting inseparable contributions of various temperature dependent phenomena arising from phonons, conduction electrons and magnons. Both the thermal expansion and mean coefficient of thermal expansion (MCT) exhibit a rising trend with temperature. The temperature dependence of the various modes of lattice, electronic, and magnetic excitations is invoked to explain the observed variations in properties. The role of the inherent electronic and magnetic structure on physical properties is highlighted.