monotectoid reaction

https://doi.org/10.1351/goldbook.M04023
A reaction in a system containing two solid solution phases, α and α in which α decomposes into α and a new phase β: αα+β
Source:
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 586 [Terms] [Paper]