ABSTRACT
Hilliard 1959; Cahn 1961, 1966). An important consideration in spinodal decomposition is the energy in the concentration gradient associated with the development of the two-phase system (Hillert 1961). This approach is now part of what is called the phase field method to model microstructure changes with diffuse rather than sharp interfaces. This is a growing and important area of computational materials science (Moelans et al. 2008; Lesar 2013). Because of their generality and completeness, these original papers require significant effort to interpret and digest and, in some cases, require advanced mathematical techniques and thermodynamic considerations beyond those being used here. Several authors have distilled the essence of the theory to provide a more pedagogical approach to spinodal decomposition, often using quite different approaches and simplifications (Kingery et al. 1976; Schmalzried 1981; Ragone 1995; Balluffi et al. 2005; Porter et al. 2008; Jackson 2010). The approach here is to use some elements of these models, along with additions, that are hopefully more transparent and lead to a step-by-step explanation of spinodal decomposition thermodynamics and kinetics. The resulting model provides the ability to actually calculate the dimensions and kinetics of decomposition rather than just describe the principles used in applying the general theory. In doing so, a regular solution is used to make concepts more concrete and only one-dimensional decomposition is considered for the sake of simplicity.
