A MONTE CARLO-FINITE ELEMENT MODEL FOR STRAIN ENERGY CONTROLLED MICROSTRUCTURAL EVOLUTION: “RAFTING” IN SUPERALLOYS

A specialized microstructural model, MCFET, has been developed which simulates microstructural evolution in materials in which strain energy plays an important role in determining morphology. The elastic contribution to the energy of the system is estimated by way of a finite element procedure which is employed in a Monte Carlo procedure to determine the microstructural evolution. This model is currently capable of accounting for externally applied stresses, surface tension, misfit, elastic inhomogeneity, elastic anisotropies (cubic) and arbitrary temperatures. The MCFET analysis has been validated by comparison with analytical calculations of the equilibrium morphologies of isolated particles in an infinite matrix. Larger simulations yield microstructures which are in good agreement with experimental observations (including the influence of applied stress). Simulations on the coarsening of two-phase microstructures containing misfitting particles suggest that the presence of strong elastic interactions greatly decreases the rate of microstructural coarsening.