Spinodal decomposition and coarsening of stressed thin films on compliant substrates
by
P.H. Leo and W.C. Johnson
in
Acta materialia, 49, pp. 1771 - 1787, 2001.
Category: Journal Article
Keywords: Phase transformations (nucleation, growth); Coarsening; Theory & modeling; Kinetics;
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Abstract:
Abstract—The microstructural evolution and long-time coarsening behavior of a thin film attached to a compliant substrate is investigated for a spinodally decomposing, binary, two-phase alloy using a Cahn– Hilliard type equation. Elastic fields arise because of composition dependence of the lattice parameter (compositional self-strain) as well as an average misfit between the film and substrate. This leads to a local mass flux within the film that depends on the global composition field as well as the thickness and elastic properties of the substrate. Three distinct coarsening regimes are observed: a rapid initial stage of spinodal decomposition into alternating phases, a transition region where internal interfaces grow and coalesce, and a final coarsening regime where the outermost layers grow with little change in the internal structure. An asymptotic expression for the long-time coarsening rate is derived as a function of the compositional selfstrain, the average misfit strain, the film thickness and the total (film plus substrate) thickness. The analytic predictions are in good agreement with numerical simulations for a variety of film and substrate thicknesses and compositional and average film misfit strains
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