Effects of Sc and Zr Addition on Microstructure and Mechanical Properties of Al-3Cu-2Li Alloy

Abstract

Different contents of Sc and Zr were designed on the basis of Al-3Cu-2Li alloy. The microstructure and mechanical properties of the alloys in different states of casting, homogenization, rolling, annealing, solution and aging were researched. The effect the additions of Sc and Zr in Al-3Cu-2Li alloy on the microstructure and mechanical properties was investigated. In Al-Cu-Li-Zr-Sc alloy, the refining strengthening effect is derived from the primary Al3(Sc,Zr) particles. Through hot rolling, intermediate annealing and cold rolling, it can be found that the microstructure of the final cold-rolled alloy is fine and compact with the increase of Sc and Zr content, while the tensile strength of the final cold-rolled Al-3Cu-2Li-0.2Zr-0.2Sc alloy reaches 409 MPa and the hardness reaches 133.6 HV. After aging at 165 °C, the hardness of Al-3Cu-2Li-0.2Zr-0.2Sc alloys increased with the prolongation of the mean time of aging. The hardness of Al-3Cu-2Li-0.2Zr-0.2Sc alloy is 174.1 HV after aging at 165 °C/20 h, but the hardness value of Al-3Cu-2Li-0.2Zr-0.2Sc alloy does not decrease when aging time increases.