Nucleation pathway in coherent precipitation

Thomas Philippe (1) , Didier Blavette (1)

1 GPM - Groupe de physique des matériaux

The non-classical nucleation pathway of coherent precipitates has been computed through the minimisation of the nucleation barrier in the composition (c) - size (R) space so that to predict the evolution of the nucleus composition. The generalized Gibbs model developed by Schmelzer et al. has been extended so that to include the misfit elastic energy. The composition of critical embryos c* has been found independent on the interfacial constant. The composition of critical nuclei (c*) was found to decrease with supersaturation. The elastic energy increases both c* and the nucleation barrier as well as R*. The evolution of the nucleus composition (c) as a function of its size (R) along the minimum energy pathway was computed. Nucleation only starts when exceeding a size threshold. Then, a rapid enrichment up to the expected composition (cβ) precedes a constant composition regime. However, for small supersaturation, the change in cluster composition can occur sharply for very small radius and then the composition slowly increases with a significant change in size. Coherency misfit energy was found to slow down the evolution of the nuclei composition with R. Model was confronted to experiments.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Thomas Philippe, Didier Blavette. Nucleation pathway in coherent precipitation. Philosophical Magazine, 2011, pp.1. ⟨10.1080/14786435.2011.616548⟩. ⟨hal-00744824⟩