Tailoring intermetallic phase and mechanical property improvement in a novel Al-Zn-Mg-Cu-Y alloy via homogenization treatment

Abstract

The modified homogenization process has garnered increasing interest in the high-alloyed materials preparation owing to its effectiveness in mitigating segregation and enhancing properties. In this work, the effects of homogenization treatment on the intermetallic phases, solidification structure and mechanical properties of a novel Al-Zn-Mg-Cu-Y alloy are investigated. The results indicate that the Al₈Cu₄Y phase is formed in the matrix and maintains steady during homogenization. It is confirmed that lower homogenization temperature (400 °C) can promote Al₃Zr nucleation, while higher temperature (460 °C) can accelerate the dissolution of MgZn₂ phase owing to a higher diffusion coefficient. Compared with single homogenization treatment, a two-stage homogenization (400 °C/16 h + 460 °C/24 h) can achieve a combination result of massive MgZn₂ phases dissolution and fine Al₃Zr dispersoids precipitation in the alloy. Moreover, the mean grain size ranges from 166.1 to 154.5 μm and its misorientation angle ranges from 39.9 to 40.9° during homogenization, suggesting a certain thermal stability for Al-Zn-Mg-Cu-Y alloy. In addition, Vickers hardness and electrical conductivity show a linear relation with the Zn, Mg and Cu elemental content in the matrix. The alloy demonstrates an improved tensile strength after homogenization, which is mainly related to MgZn₂ dissolution and Al₃Zr precipitation.