Effect Of Aging Treatment On Microstructure And Properties Of Al-Zr-Sc(-Er) Alloys

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 Al-3 (Er, Sc, Zr) phases with core-double shell structure. For experimental alloys, one-stage aging at 300 degrees C provides the higher hardness but lower electric conductivity ; one-stage aging at 400 degrees C can increase the aging response speed and electrical conductivity but decrease hardness ; two-stage aging at 300 degrees C/24 h + 400 degrees C can lead to better match of conductivity, tensile strength and heat resistance.