Multi-scale characterization and modeling of chromium carbide based cermets

High-resolution measurements of mechanical properties of composites produced by powder metallurgy techniques are of importance for a reliable materials production. Measuring the intrinsic properties of each phase separately in multiphase composites gives the information on the spatial heterogeneity in local material properties and serves as a guide to process engineering and advanced materials design. In this study, the nanoindentation, X-ray analysis and microstructural SEM investigations were used to obtain the properties and structural features of ceramic - metal composites involving three-phase chromium carbide-based cermets Cr₃C₂-Cr ₇C₃-CrNi₃ of different binder compositions. Thermal residual stresses were significantly reduced by alloying with molibdenum and copper while the mechanical properties (elastic modulus and hardness) were very affected. Finally, theoretical modeling was used to predict effective elastic moduli and thermal residual stresses of such composites. The Hashin-Shtrikman bounds were used to predict the effective elastic moduli and the Mori-Tanaka micromechanics method was used to obtain the local thermal stress fields of these composites. We found a very good agreement between theoretical and experimental results for effective elastic moduli but the results were further apart for thermal residual stress predictions.