First-principles study of lattice thermal conductivity in concentrated solid solution alloys

Energy dissipation of concentrated solid solution alloys can be controlled by the number and types of alloying elements and has impacts on the defect formation and recombination after radiation. Here we use an ab-initio supercell method combined with a phonon unfolding technique to access the effects of disorder on the lattice-mediated thermal conductivity in a series of 2-4 component equiatomic alloys (e.g. NiFe, NiCo, NiCoCr, NiFeCo, NiFeCoCr) where the mass disorder is small while the force constant disorder is pronounced. We demonstrate that force constant disorder itself can efficiently reduce the thermal conductivity. We further show that the low-conductivity Cr-containing alloys present the largest force constant fluctuations across the studied alloys and that this is electronically driven. The results provide a new tuning parameter, based on the electronic structure, to manipulate the force constant disorder, thereby facilitating the design of materials with desirable thermal transport properties.