Effect of aging treatment on microstructure and properties of Al-Zr-Sc(-Er) alloys

Abstract

The effects of aging treatment on microstructure and properties of Al-Zr-Sc(-Er) alloys were investigated by TEM, STEM, hardness tests and electric conductivity tests systematically. Results show that the aging response speed, peak hardness and thermal stability of Al-Zr-Sc alloys are significantly improved by increasing Sc content, and increasing Zr content improves hardness and thermal stability, while decreasing the electric conductivity. Adding Er in Al-Zr-Sc alloys improves the aging response speed and promotes the precipitation of Zr and Sc. Hardness and electrical conductivity of alloy are improved, owing to the formation of Al3(Er, Sc, Zr) phases with core-double shell structure. For experimental alloys, one-stage aging at 300℃ provides the higher hardness but lower electric conductivity; one-stage aging at 400℃ can increase the aging response speed and electrical conductivity but decrease hardness; two-stage aging at 300℃/24 h+400℃ can lead to better match of conductivity, tensile strength and heat resistance.

Keywords

• al-zr-sc(-er) alloy
• aging
• microstructure
• electric conductivity