Solid State Precipitation: Session III
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Seth Imhoff, Los Alamos National Laboratory; Robert Hackenberg, Los Alamos National Laboratory; Gregory Thompson, University of Alabama

Thursday 2:00 PM
March 2, 2017
Room: 25A
Location: San Diego Convention Ctr

Session Chair: Seth Imhoff, Los Alamos National laboratory

2:00 PM  Invited
Atomic Theory of Spinodal Decomposition: Maylise Nastar1; 1CEA
    The phenomenological theories currently used to describe phase decomposition in solids fail to predict the early stage of a spinodal decomposition mainly because they rely on local equilibrium assumptions. Within the Self-Consistent Mean Field (SCMF) theory, it is shown that spinodal decomposition and more generally kinetics of nanoscale composition fluctuations are correctly described if deviations of short range order from local equilibrium are accounted for. The resulting structure function of a binary system is controlled by a sum of exponential laws, in agreement with atomic Monte Carlo simulations and small angle scattering observations of spinodal decomposition. Moreover, in the case of a point defect diffusion mechanism, diffusion of atoms is non random and the inter-diffusion coefficient controlling the concentration fluctuations is shown to be in discrepancy with a Cahn-Hilliard like formulation. These theoretical results are applied to the modeling of spinodal decomposition in Fe-Cr alloys.