A high-strength Al-Cu-Sc alloy fabricated by rapid solidification and direct aging

Abstract

The effect of solidification rates and heat treatment on the microstructure and mechanical properties of Al-Cu-Sc alloys was investigated. The results demonstrate that rapid solidification (RS) effectively prevents the formation of the W phase, which is common in conventional solidification (CS) alloys. Additionally, the supersaturated Cu solute within the RS matrix facilitates direct aging, leading to uniform and fine θ′ precipitates. Although the number density of θ′ is slightly lower than in the CS Al-Cu + T6 alloy, the dense Al3Sc nanodispersoids compensate for the strength loss in another aspect. As expected, the RS Al-Cu-Sc + aging alloy exhibits superior tensile strengths and ductility. The improvement in strength can be primarily attributed to Orowan strenthening and precipitation strengthening, related to Al3Sc nanodispersoids and θ′ precipitates.