General information on transformations of solid solutions

Until now we have only considered transformations of pure A solids. We will now consider transformations in which the initial solid belongs to a solid solution, which has as a consequence that this solution contains at least two components. 

In a solution containing at least two components (which are called A1 and A2), two main categories of transformations can occur. 

The thermodynamic conditions can be such as only one component, for example Al, of the solid solution is likely to react. We then say that we have a selective reaction of this component, which can lead to a pure solid or a new solid solution. 

It is allowed by the thermodynamic conditions that both components of the initial solid solution Al and A2 can react, then under these conditions, there are two 

It is clear that the multiphcation of the reactions will induce important complications on the reactional zones and their dimensions. 

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