CALORIMETRIC STUDY ON PRECIPITATION PATH IN 2024-ALLOY AND ITS SIC COMPOSITE

Differential scanning calorimetry (DSC) is used in order to investigat e the aging behaviour of Al-Cu-Mg alloys with different Cu:Mg ratios. Mechanism and kinetics of aging for these materials are compared with those of an (Al-Cu-Mg)-SiC composite. DSC results are in fairly good a greement with metastable Al-Cu and Al-Cu-Mg phase diagrams. The SiC re inforcement does not affect the precipitation path; furthermore, the a ctivation energy for theta'' precipitation, calculated by Ozawa's meth od, is not appreciably different, taking into account the experimental error, for unreinforced alloy and composite. However, all the transfo rmations involved in the aging sequence are shifted towards lower temp eratures during the DSC scans of the composite material.