Microstructure dependent thermal conductivity measurement of Zircaloy-4 using an extended Raman thermometry method

In this work, microstructural dependence of thermal conductivity of two polycrystalline zircaloy-4 samples was analyzed by using an extended Raman thermometry method. The thermal conductivity values in examined microstructures were found to vary spatially from 11 to 13 W m(-1)K(-1). These values are in the range reported by other bulk measurements that do not consider spatial distribution. The Kapitza thermal resistance model is shown to describe the measured dependence of thermal conductivity as a function of grain size. Thermal resistance from grain boundaries and inhomogeneities are identified as two potential contributors to the thermal conductivity reduction. Nanoindentation tests were performed to obtain the local elastic modulus distribution in the analyzed samples. The thermal conductivity values increase with elastic modulus increasing in each sample. This result indicates a possibility that at room temperature phonon thermal conductivity makes a non-negligible contribution to the total thermal conductivity in zircaloy-4. (C) 2020 Elsevier B.V. All rights reserved.