Abstract
The early stages of formation of the L12 ordered δ'-phase are discussed on the basis of experimental results referring to room-temperature precipitation taking place in alloys quenched after solution treatment. The initial process is a fast continuous ordering followed by a considerably slower decomposition. Indications were found for a homogeneous nucleation process occurring in the congruently ordered matrix. The ordered nature of the δ' precipitates determines their effect on mechanical properties. Both the homogeneously ordered matrix and the ordered precipitates favour planar slip which appears already in as-quenched specimens.