peritectoid reaction

An isothermal, reversible reaction in the solid state, that, on cooling of a binary, ternary, ... , $n$ system, results in one, two, ... ( $n − 1$ ) new solid phases. For example, in a binary system containing two solids $α '$ and $α ''$

$α ' + α '' → β$

Synonymous with metatectoid reaction.

Source:

PAC, 1994, 66, 577 (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 588

peritectoid reaction

Synonym: metatectoid reaction