Effect of Sc addition on the microstructure, mechanical properties, and damping capacity of Al-20Zn alloy

In this study, hot rolling (HR), solid solution treatment (ST), and friction stir processing (FSP) were applied to Al-20Zn and Al-20Zn-0.5Sc alloys to obtain their elongated, coarsened, and fine-equiaxed grain structures. Sc addition refined the grains of Al-20Zn alloys in any state. The dynamic precipitation during deformation, such as HR and FSP, was promoted by the Al3Sc phase in the alloy containing Sc. The strength of Al-20Zn alloy was improved by Sc addition. Furthermore, a reasonable ductility was obtained in the ST sample when added with Sc. The fine grains and high density of Al3Sc particles with grain boundary pinning effect resulted in increased high-temperature internal friction value and excellent damping stability of the HR and FSP Al-20Zn-0.5Sc samples.