Development of a high-strength Al-Zn-Mg-Cu-based alloy via multi-strengthening mechanisms

We develop high-strength of Al-Zn-Mg-Cu-based alloys (7xxx series) by optimizing the amount of Mg/Cu with a trace addition of Sc. The highest mechanical properties are achieved with σUTS=672 MPa (σy=644 MPa) and ε=8.6%. Based on quantitative symmetry measurements, the improved mechanical strength originates from nanoscopic structural distortion caused by the excessive solutes of Mg and Cu as the amount of Mg/Cu increases. In addition, Sc microalloying induces grain refinement, thus enhancing the mechanical properties.