A calorimetric study of S′ and θ′ precipitation in Al2O3 particle-reinforced AA2618.

Differential scanning calorimetry (DSC) was used to study the kinetics of S′ and θ′ precipitation in AA2618 and its composite containing 15 vol % Al₂O₃ particles . The unreinforced alloy and the composite were fabricated by a proprietary casting method, followed by extrusion. The DSC studies were carried out on as-quenched samples of the test materials. The precipitation of the S′ and θ′ phases in both materials was found to be kinetically controlled and obey the modified Avrami-Johnson-Mehl equation. The growth mechanisms for S′ and θ′ formation in AA2618 seemed unaffected by the addition of Al₂O₃ particles. The growth parameters obtained for the precipitation of these phases in the matrix alloy and the composite were not significantly different. [ABSTRACT FROM AUTHOR]