Grain growth in thin films with a fiber texture studied by phase-field simulations and mean field modeling
Résumé
The evolution of fiber textured structures is simulated in 2 dimensions using a generalized phase-field model assuming two forms for the misorientation dependence of the grain boundary energy. In each case, a steady-state regime is reached after a finite amount of grain growth, where the number and length weighted misorientation distribution functions (MDF) are constant in time, and the mean grain area $A$ as a function of time $t$ follows a power growth law $A-A_0 = k t^n$ with $n$ close to 1 and $A_0$ the initial mean grain area. The final shape of the MDF and value of the prefactor $k$ in the power growth law clearly correlate with the misorientation dependence of the grain boundary energy. Furthermore, a mean field approach is worked out to predict the growth exponent for systems with nonuniform grain boundary energy. The conclusions from the mean field approach are consistent with the simulation results. In previous studies on grain growth in anisotropic fiber textured systems, this steady-state regime was often not reached, which resulted in wrong conclusions on the growth exponent $n$ and evolution of the MDF.
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