Estimation of the effective conductivities of complex cast iron microstructures using FIB-tomographic analysis

We present the influence of microstructural characteristics of different graphite morphologies on the effective properties of cast iron. First, the properties are compared with existing analytical bounds and predictive schemes. The estimation of the properties of nodular, flake and all intermediate graphite morphologies becomes possible after the analysis of the graphite crystal structure and growth mechanisms. These properties are implemented in a two-dimensional finite element model. It is shown that the consideration of microstructural parameters - volume fraction, surface density and particle shape - provides good estimates of the properties of cast iron with simply connected nodular graphite particles, but is insufficient for interconnected structures with vermicular and flake graphite. The agreement of the experimental results with three-dimensional simulations on real tomographic data proves that the connectivity of phases is one of the determining factors for material properties.