title: Precipitation of a new platelet phase during the quenching of an Al-Zn-Mg-Cu alloy.
abstract: A previously undescribed high aspect ratio strengthening platelet phase, herein named the Y-phase, has been identified in a commercial Al-Zn-Mg-Cu alloy. Differential scanning calorimetry indicates that this phase only precipitates at temperature and cooling rate of about 150-250 °C and 0.05-300 K/s, respectively. This precipitate is shown to be responsible for a noticeable improvement in mechanical properties. Aberration corrected scanning transmission electron microscopy demonstrates the minimal thickness (~1.4 nm) precipitate plates are isostructural to those of the T1 (Al2CuLi) phase observed in Al-Cu-Li alloys. Low voltage chemical analysis by energy dispersive X-ray spectroscopy and electron energy loss spectroscopy gives evidence of the spatial partitioning of the Al, Cu and Zn within the Y-phase, as well as demonstrating the incorporation of a small amount of Mg.
authors.affiliation: Department of Materials Science and Engineering, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, Monash University, Clayton, VIC 3800, Australia.|Monash Centre for Electron Microscopy, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Weyland
authors.affiliation: Chair of Materials Science, Faculty of Marine Technology and Mechanical Engineering, University of Rostock, 18051 Rostock, Germany.|CALOR - Research Competence Center Calorimetry and Thermal Analysis Rostock, Faculty for Interdisciplinary Research, Department Light, Life and Matter, University of Rostock, 18051 Rostock, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Milkereit
authors.affiliation: Chair of Materials Science, Faculty of Marine Technology and Mechanical Engineering, University of Rostock, 18051 Rostock, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reich
authors.affiliation: Department of Materials Science and Engineering, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Rometsch