Controlling Thermal Conductivity of Alloys via Atomic Ordering

Abstract

Many random substitutional solid solutions (alloys) will display a tendency to atomically order given the appropriate kinetic and thermodynamic conditions. Such order–disorder transitions will result in major crystallographic reconfigurations, where the atomic basis, symmetry, and periodicity of the alloy change dramatically. Consequently, phonon behavior in these alloys will vary greatly depending on the type and degree of ordering achieved. To investigate these phenomena, the role of the order–disorder transition on phononic transport properties of Lennard–Jones type binary alloys is explored via nonequilibrium molecular dynamics simulations. Particular attention is paid to regimes in which the alloy is only partially ordered. It is shown that by varying the degree of ordering, the thermal conductivity of a binary alloy of fixed composition can be tuned across an order of magnitude at 10% of the melt temperature, and by a factor of three at 40% of the melt temperature.