A new model to describe composition and temperature dependence of thermal conductivity for solution phases in binary alloys

Modelling temperature- and composition-dependent thermal conductivity in alloys is challengeable and is seldom studied systematically. In the present work, a new model is developed to describe the temperature and concentration dependence of thermal conductivity for binary alloys. In this new model, firstly thermal conductivity of pure metals was modelled as the function of temperature for each phase and each magnetic state by the corresponding physically sound model. Secondly, in order to describe the composition and temperature dependence of thermal conductivity for solid phases, the combination of the theories of Nordheim and Mott for electric conductivity of alloys with the Wiedemann-Franz law was performed. Thirdly, the reliability of the new model was verified by presently measured thermal conductivities for pure Co, Ni and Co-Ni alloys at 300, 600, 900 and 1100 K as well as for binary Al-Zn, Mg-Zn and U-Zr systems using the data taken from the literature. The calculated thermal conductivities can well reproduce the measured ones in one-phase regions of a series of Co-Ni alloys. The thermal conductivity in a two-phase region of the Co-Ni system is reasonably predicted as well. It is demonstrated that the new model can be utilized to evaluate the thermal conductivity over the whole investigated composition and temperature ranges for the first time and is expected to be extended to ternary and multicomponent systems by CALPHAD method, which contributes significantly to the development of computational design of materials.