Abstract
Precipitation hardening is one of the dominant strengthening mechanisms for Mg alloys, especially for Mg alloys containing rare earth elements. However, precipitation hardening of conventional Mg alloys (such as AZ91D, ZK60 or even WE54/43) is relatively weaker than in high performance Al alloys [such as Al–Cu–Mg based alloys (2024) and Al–Zn–Mg–Cu based alloys (7075, 7050)]. Further avenues for improving precipitation hardening of Mg alloy are therefore being actively explored. In this paper, co-precipitation on the basal and prismatic planes of the α-Mg matrix in a Mg–2.4Gd–0.4Ag–0.1Zr alloy after over-ageing at 200 °C for 2048 h was investigated using high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) imaging and electron energy loss spectroscopy (EELS). Ag was observed within precipitates on the basal plane, while Gd was observed within precipitates on both the basal and prismatic planes. Furthermore, Ag, Gd-rich clusters were also observed in the vicinity of these precipitates, which were proposed to form during solution treatment and to coarsen during subsequent ageing treatment.
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Acknowledgements
The author (J.H. Li) acknowledges the casting sample preparation from Shanghai Jiaotong University and the financial support from the Major International (Regional) Joint Research Project (No. 51420105005) from China and the projects (EPU 04/2017, CN 09/2016, mmc-kf15-11). The authors (Y.J. Wu and L.M. Peng) acknowledges the financial support from the National Key Research and Development Program of China (No. 2016YFB0301000) and National Natural Science Foundation of China (No. 51671128). The SuperSTEM Laboratory is the U.K. National Facility for Advanced Transmission Electron Microscopy, supported by the Engineering and Physical Sciences Research Council (EPSRC). SJH and AG thank EPSRC for funding under grant EP/M010619/1.
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Li, J. et al. (2018). Co-precipitation on the Basal and Prismatic Planes in Mg–Gd–Ag–Zr Alloy Subjected to Over-Ageing. In: Orlov, D., Joshi, V., Solanki, K., Neelameggham, N. (eds) Magnesium Technology 2018. TMS 2018. The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-319-72332-7_59
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DOI: https://doi.org/10.1007/978-3-319-72332-7_59
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