Solute clusters-promoted strength-ductility synergy in Al-Sc alloy

Sc solute clusters with a high number density were produced in an Al-0.3 wt.%Sc alloy when aged at 250 °C, while fine Al₃Sc precipitates were predominantly formed in the same alloy aged at 300 °C. The alloy strengthened by Sc solute clusters displayed higher yield strength and simultaneously greater ductility than its counterpart strengthened by Al₃Sc precipitates. This clearly demonstrates a superior strength-ductility synergy promoted by the Sc solute clusters in Al-Sc alloys. The effects of Al₃Sc precipitates and Sc solute clusters on ductility were discussed in comparison by using a micromechanics fracture model. Since the Sc clusters were stabilized at 250 °C, the Al-Sc alloys strengthened by Sc solute clusters should find extensive application fields within a wide temperature range, due to their high temperature resistance.