Monte Carlo studies of grain boundary segregation and ordering

This paper describes a systematic microscopic study of solute segregation and ordering at a grain boundary. We develop for this inhomogeneous system several Monte Carlo techniques and apply these to analyze the distribution of substitutional impurities near a symmetric coincident‐site‐lattice tilt boundary. The calculations demonstrate the importance of ensemble and boundary condition for a Monte Carlo simulation, especially one with an inhomogeneous lattice and with ordering, as opposed to segregating, bulk interactions. The resulting concentration profiles exhibit segregation to the boundary at high temperatures and bulk ordering at low temperature. Based on our results, we propose a mechanism for a solid–solid interfacial ordering phase transition previously suggested by experiment. We also compare these simulations to our earlier one‐dimensional mean‐field work and find that the three‐dimensional simulations confirm the essential mean‐field predictions.