Morphology and chemical nanoanalysis of discontinuous precipitation in MgAl allyos—II. Irregular growth

Loacl chemical analysis of discontinuous precipitation in MgAl alloys has been performed in various cases where the lamellae exhibit a change in habit plane. It is shown that such an event is always preceded by the appearance of an asymmetry in the solute concentration profile in the α lamellae, and that it results in a decrease of this asymmetry. From a stability analysis of the grain boundary shape, a scenario is proposed for explaining the occurrence of these changes in habit planes.