A phase field model for a polycrystalline alloy was developed by combining the Cahn–Hilliard model with the Fan-Chen model for polycrystals. This model was used to study grain boundary effects upon spinodal decomposition in 2-dimensional systems. In binary A–B systems with constant atomic mobility, when the grain-boundary energy (γα) of the A-rich α-phase was lower than that (γβ) of the B-rich β-phase, decomposition began by enrichment of the grain boundary with species A; setting off a composition wave that produced alternating α and β bands near to the grain boundary. At the same time, the grain interiors underwent normal spinodal decomposition. Thus, when decomposition ended, grain-boundary bands co-existed with grain interiors having a spinodal microstructure. The number of grain-boundary bands was explained in terms of γβ-γα, and the rate of spinodal decomposition in the grain interior. Grain growth was effectively suppressed during decomposition.

Phase Field Study of Grain Boundary Effects on Spinodal Decomposition. H.Ramanarayan, T.A.Abinandanan: Acta Materialia, 2003, 51[16], 4761-72