__Last time: Spinodal decomposition--I.__

__Background__

- Pair interaction model with conserved and nonconserved variables

- Diffusion within the spinodal

- Free energy of an inhomogeneous system

__Today: Spinodal decomposition--II.__

__Gradient energy__

__Elastic energy__

__Improved diffusion equation__

- Modification to Fick's laws
- Solution to diffusion equation
- Spinodal microstructures
- Later stages of spinodal decomposition

__Spinodal decomposition--II.__

__Gradient energy__

*The "uphill" diffusion that results within the spinodal leads to the
evolution of a high density of material in which there are
significant gradients of composition. These gradients have an
associated excess energy that diminishes the available driving force
for diffusion. Thus, there must be a gradient energy modification to
the diffusion potential and consequent modifications to Fick's laws
for diffusion.
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__Elastic energy__

*If there is a change of molar volume with composition, solid-state
diffusion will be accompanied by changes of elastic energy. The
elastic energy contribution for compositional inhomogeneities enters
the expressions for the , as well as the diffusion potential and
Fick's laws.
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*When the material is elastically anisotropic, the elastic energy will
depend on the orientation of the developing composition wave.
The wavevector will tend to align along elastically soft directions
in the material.
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*When elastic energy is significant, the region of compositional
instability in the phase diagram is reduced, and the smaller unstable
region is known as the coherent spinodal.
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__Improved diffusion equation__

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__Solution to modified diffusion equation__

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__Spinodal microstructures__

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__Later stages of spinodal decomposition: nonlinear effects__