A phase-field model for grain growth with trijunction drag

A phase-field model has been developed to study the effect of triple junction (TJ) mobility on 2-D grain growth kinetics. The method captures the results of past work such as a linear increase in the average grain size with time, but can also follow the transition from TJ-limited to grain boundary energy-limited growth. The distribution of grain boundary curvature is examined. In the low TJ mobility simulations the distribution has a peak at zero curvature and approaches the grain boundary mobility-limited steady-state distribution at larger sizes. Even for extremely low TJ mobility, a small fraction of the grain boundary length has non-zero curvature and thus a lack of self-similarity is observed for all TJ-limited simulations, even when the average size is increasing linearly in time. We find that the topology of the grain structure is independent of the degree of TJ drag, within the range of parameters employed in the simulation. The effects of TJ mobility increase as the grain size decreases, suggesting that TJ mobility can play a significant role in nanocrystalline grain growth kinetics.