Effects of Sc and Zr on microstructure and mechanical properties of Al-Zn-Mg-Cu aluminum alloy

A series of Al-9.0Zn-2.8Mg-2.5Cu alloys with different additions of Sc, Zr and Sc+Zr were prepared by ingot-metallurgy processing. The metallurgical structure and mechanical properties were investigated by optical microscope, universal testing machine and other equipment. The results indicated that when Sc and Zr are added respectively, the tensile strength of alloy increases gradually and the elongation decreases with the increase of addition; the tensile strength and the elongation are 775 MPa and 785 MPa, 9.95% and 7.1%, respectively. When the addition increases from 0.15% to 0.25%. When Sc and Zr are added compositely, if the content of Sr is less than Zr, the tensile strength increases and then declines with the increase of additions, and the elongation gradually decreases. When the addition is up to 0.04%Sc and 0.12%Zr, the tensile strength reaches the maximum value of 775 MPa and the elongation declines to 9.85%.