The low temperature lattice thermal conductivity of deformed copper alloys

The thermal conductivities of polycrystalline copper alloys containing 2 and 12 at.% aluminium, 10 at.% gold and 30 at.% Zn have been measured between 1·5 and 4·2 K in the annealed state and after tensile deformation. A single crystal of Cu-12 at.% Al has also been studied after various stages of deformation. It has been found that the thermal conductivity of the deformed specimens is not a simple quadratic function of temperature throughout the range studied. This has been attributed to the scattering of phonons by dislocations whose separation is less than the phonon wavelength. A simple mathematical model based on this theory gives results in good agreement with experiment and shows that it is possible to account for the temperature dependence of the lattice thermal conductivity on a strain field model.