Morphology and chemical nanoanalysis of discontinuous precipitation in MgAl alloys—I. Regular growth

Discontinuous precipitation in MgAl alloys has been studied both by conventional TEM (morphology) and STEM with local chemical analysis (concentration profiles). Numerous growth defects have been identified. In the case of regular growth, a detailed analysis of concentration profiles using Cahn's solution has been performed, proving the necessity to introduce three velocity scales in order to describe the overall kinetics. The thermodynamical balance of the phenomenon has been derived by applying Hillert's model.