Effect of Interfacial Segregation on Phase Decomposition of a Thin Film on a Patterned Substrate

Numerical simulations of phase decomposition in thin films on patterned substrates are presented for a binary alloy in order to study the influence of substrate composition on microstructural evolution. For systems with a substrate composition less than the film composition, a preferential segregation of A to the interface was observed and no phase decomposition occurred within the film. For patterned systems with a substrate composition exceeding the film composition, the B-rich phase was able to grow by a barrierless transformation for a range of film compositions outside the chemical spinodal. The number of precipitates which formed on the mesa, the dihedral angles at the three-phase trijunctions, and the resulting microstructure within the film were shown to be sensitive to the substrate composition.