Calorimetric study on precipitation path in 2024 alloy and its SiC composite

Differential scanning calorimetry (DSC) is used in order to investigate the aging behaviour of AlCuMg alloys with different Cu:Mg ratios. Mechanism and kinetics of aging for these materials are compared with those of an (AlCuMg)-SiC composite. DSC results are in fairly good agreement with metastable AlCu and AlCuMg phase diagrams. The SiC reinforcement does not affect the precipitation path; furthermore, the activation energy for θ″ precipitation, calculated by Ozawa's method, is not appreciably different, taking into account the experimental error, for unreinforced alloy and composite. However, all the transformations involved in the aging sequence are shifted towards lower temperatures during the DSC scans of the composite material.