Precipitation of a new platelet phase during the quenching of an Al-Zn-Mg-Cu alloy

Yong Zhang, Matthew Weyland, Benjamin Milkereit, Michael Reich, Paul A. Rometsch

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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 T 1 (Al 2 CuLi) 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.

Original languageEnglish
Article number23109
Number of pages9
JournalScientific Reports
Publication statusPublished - 16 Mar 2016

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