High-throughput thermal conductivity measurements of nickel solid solutions and the applicability of the Wiedemann-Franz law

Thermal conductivity mapping with a spatial resolution of 3 mu m and an acquisition speed of 3 points per second has been applied to binary Ni(Cr), Ni(Pd), Ni(Pt), Ni(Rh) and Ni(Ru) solid solutions to test the applicability of the Smith-Palmer equation and the Wiedemann-Franz: law to Ni alloys. The lattice thermal conductivity of pure Ni and Ni(Pd) alloys is calculated by molecular dynamics. After subtracting the lattice component from the total thermal conductivity, the electronic thermal conductivity of pure Ni is 25% smaller than that predicted from the Wiedemann-Franz law. With the addition of solutes of Pt and Rh, the deviation from the Wiedemann-Franz law decreases. However, the negative deviation of the electronic thermal conductivity of Ni(Pd) alloys from the Wiedemann-Franz law increases slightly to 29% when the Pd concentration is 40 at.%. The Smith-Palmer equation is not a generally reliable method for predicting the thermal conductivity of Ni solid solution alloys from measurements of the electrical conductivity. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.