Abstract:The aging behavior of 2618 (Al-Cu-Mg-Fe-Ni) alloy added trace Sc and Zr was studied by Vicker’s hardness measurement at 200 and 300℃, and the tensile properties(yield strength, ultimate tensile strength and elongation) of alloys were measured at 20, 200, 250 and 300℃. The microstructures were observed by using optical microscope, SEM and TEM. It was found that the addition of Sc and Zr to 2618 alloy resulted in a uniform distribution of fine coherent Al₃(Sc,Zr) precipitates which had obvious aging hardening effect and made the S’phase precipitate more homogeneously. The strength of alloy increased at ambient and elevated temperature without a decrease of ductility because of the precipitation strengthening and thermal stability of Al₃(Sc,Zr) particles. The ductile fracture of alloy occurred by microviod nucleation, growth and coalescence, so the microvoid coalescence was the dominant fracture mechanism. Al₃(Sc,Zr) particles could inhabit the recrystallization process of alloy 2618.

Key words: scandium; zirconium; addition; 2618 alloy; tensile property