Atomic-scale investigation of the heterogeneous precipitation in the E (Al18Mg3Cr2) dispersoid of 7075 aluminum alloy
(2021) Journal of Alloys and Compounds — Vol. 851, p. 156890 (2021)
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- Authors
Zhao, Lv 
- Abstract
- The heterogeneous precipitation of the η (MgZn2) phase on the E (Al18Mg3Cr2) dispersoids of the 7075 aluminum alloy was systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive X-ray spectrometry (EDX). It is found that coarse η particles are heterogeneously precipitated at the E particle interface after water quenching and isothermal aging at 120 °C. The incoherent E/Al interface is responsible for the high tendency of heterogeneous precipitation of the η phase. Two different orientation relationships (ORs) between the η, E and Al matrix are identified: OR1 [20]η//[011]E//[12]Al, (01)η//(13)E//(21)Al, OR2 [12]E//[0001]η//[011]Al, (01)η//(220)E//(3)Al. The η phase is preferential to nucleate along the {111}E or the {220}E planes, depending on its OR. The heterogeneous nucleation of η phase on the E particle could stabilize the E/Al interface by introducing a coherent E/η interface, which increases the drive force of heterogeneous precipitation. The reorientation of η phase and mutual diffusion of solute atoms could assist the coherency of the E/η interface. The present results suggest that increasing the coherency of the E/Al interface is a promising method to suppress the heterogeneous precipitation of the η phase.
- Affiliations
Nanjing Tech University Key Laboratory for Light-weight Materials University of AntwerpTech University Electron Microscopy for Materials Science (EMAT) Huazhong University of Science and Technology Department of Mechanics Nanjing Institute of Technology School of Materials Science and Engineering
Citations
Ding, L., Zhao, L., Weng, Y., Schryvers, D., Liu, Q., & Idrissi, H. (2021). Atomic-scale investigation of the heterogeneous precipitation in the E (Al18Mg3Cr2) dispersoid of 7075 aluminum alloy. Journal of Alloys and Compounds, 851, 156890. https://doi.org/10.1016/j.jallcom.2020.156890 (Original work published 2021)