Ordering and separation in phase diagrams

Solid-solution fields in the generally accepted type-IV phase diagrams are shown to exhibit a tendency toward separation, which causes the formation of separation microstructures. Numerous examples of separation in solid solutions are given; this separation occurs at temperatures both above and below the fields of chemical compounds. Separation and ordering fields are separated by metastable-solid-solution regions in phase diagrams. At the temperatures corresponding to these regions, an ordering-separation phase transition takes place. New versions of the Fe-Cr, Fe-Co, and Fe-V phase diagrams are presented.