Coarsening Kinetics of Al₃Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Abstract

The coarsening of Al₃Sc precipitates in an Al–1 mass%Mg–0.27 mass%Sc alloy aged at 573 K has been examined using a model developed by Kuehmann and Voorhees. The average size of Al₃Sc precipitates was evaluated by transmission electron microscopy and electrical resistivity was employed to measure the Sc concentration in the matrix. Kinetic analyses revealed that before the onset of a coarsening stage, there exist mixed stages of nucleation and growth and of growth and coarsening. The coherent Al/Al₃Sc interface energy γ is estimated as 0.23 Jm⁻² from data on coarsening alone. The transition from a coherent interface to a semi-coherent interface caused no change in γ.