(616f) Effects of Grain Size Distribution on Creep Damage in Polycrystalline Materials By a Monte Carlo Simulation

The effects of grain size distribution on creep damage, induced by abnormal grain growth in polycrystalline materials is investigated using a multi-scale mesoscopic simulation approach. The phenomenological modified-Potts free energy functional is adopted and parametrized to predict grain size distribution and shape. The microstructure's evolution is simulated introducing a constitutive model for grain-boundary diffusion, where the effects of boundary topology and grain growth are analyzed. A hybrid Monte-Carlo and molecular-like dynamics method is developed to account for the slow dynamics. Experimental data, from scanning electron microscope to collect a series of electron backscatter diffraction (EBSD) maps of the microstructure are used to parametrize the free energy functional. The simulations correlate with experimental observations where a decrease grain size leads to higher creep strain rates. In addition, a uniform grain size distribution is associated to higher creep strain rates. The implications for high-temperature plasticity mechanical behaviour are discussed. This kind of mesoscopic simulation approach will be the framework for the study of creep in metals and ceramic materials at high-temperature like thermal barrier coatings used in gas turbines for power generation