Influence of Overaging on the Superplastic Behavior of an Al-Zn-Mg-Cu-Zr-Sc Alloy

Abstract

This study examines the influence of overaging on the superplastic behavior of an Al-8.55Zn-2.65Mg-2.48Cu-0.1Zr-0.06Sc alloy (in mass%). Results show that the M-phase particles formed during overaging play the most crucial role during the high-temperature tensile deformation of the Al-Zn-Mg-Cu-Zr-Sc alloy. Even though specimens without overaging maintain their small grain structure due to the existence of fine coherent Al₃(Sc_xZr_1−x) particles, overaged specimens exhibit better superplasticity. The presence of liquid-like viscous flow may be the main factor contributing to the superior superplasticity of overaged specimens.