| Abstract Scope |
Al-Zn-Mg 7xxx series alloys have been used in automobiles as structural materials due to their high specific strength by η-MgZn2 type metastable precipitates formed during heat treatment. Furthermore, The metastable L12 phase has been reported to contribute dispersion strengthening and thermal stability, independent of main precipitates. However, only a few studies on the ternary core-shell structure of Y-contained L12 phase has been reported to date, unlike binary one. In this study, we investigate the effects of L12 phase formed by microalloying Zr, Er, and Y on the aging behavior of η-MgZn2 type precipitates in 7xxx series alloys. The Zr-Er-Y-modified and reference alloys were solutionized, followed by subsequent artificial aging. The microhardness measurements, TEM observations, and APT analyses were performed to monitor the effects of precipitates and L12 phases, resulting that the multi addition of Zr-Er-Y elements causes decreasing size and significantly increasing number density of both precipitates and L12 phases. |