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 degreesC is followed by a gradual increase to near saturation around 900 degreesC. 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<degrees>C, beyond which it saturates to a value of similar to0.17 W/cm-degreesC. 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 csp]ain the observed variations in properties. The role of the inherent electronic and magnetic structure on physical properties is highlighted. (C) 2000 Elsevier Science Ltd. All rights reserved.