https://doi.org/10.1351/goldbook.M04023
A reaction in a system containing two @M03940@ phases, \(\alpha\mathit{'}\) and \(\alpha\mathit{''}\) in which \(\alpha\mathit{'}\) decomposes into \(\alpha\mathit{''}\) and a new phase \(\beta \): \[\alpha\mathit{'}\rightleftharpoons \alpha\mathit{''}+\beta \]