Effects of intergranular gas bubbles on thermal conductivity

Model microstructures obtained from phase-field simulations are used to study the effective heat transfer across bicrystals with stationary grain boundary bubble populations. We find that the grain boundary coverage, irrespective of the intergranular bubble radii, is the most relevant parameter to the thermal resistance, which we use to derive effective Kapitza resistances that are dependent on the grain boundary coverage and Kaptiza resistance of the intact grain boundary. We propose a model to predict thermal conductivity as a function of porosity, grain-size, Kaptiza resistance of the intact grain boundary, and grain boundary bubble coverage.