A transition that occurs within a phase. Example: initiation of phase growth at an intragranular feature, such as twin planes and dislocations in steels.
Source:
PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 584 (https://doi.org/10.1351/pac199466030577)