A case for non-steady-state grain growth kinetics

Grain growth is typically analyzed in context of steady-state kinetic models, even though ‘jerky’ non-steady-state response is commonly observed. This work derives general equations describing non-steady-state grain growth kinetics, which are validated against two-dimensional phase field simulations with pinning processes active. These equations when coarse-grained capture commonly observed grain growth phenomena by producing power law kinetics like steady-state models. The steady-state and non-steady-state models, however, make qualitatively different predictions and interpretations of grain growth response. The discussion highlights how non-steady-state models may be useful for interpreting the stochastic nature of grain growth, apparent activation energies measured from abnormal grain growth, and phenomena related to grain growth stagnation.