Fig. 1. (a) Original Mg microparticles with a diameter of 46 μm; (b) XRD pattern of Mg microparticles.

Fig. 2. Illustration of fabrication process used in this study.

Fig. 3. Microstructure of different Al-Mg intermediate samples: (a)-(d) Mg elemental distribution of Al-17Mg intermediate samples after ARB with different N ((a) 10; (b) 30; (c) 50; (d) 70) characterized by SEM-EDS; Insets are the corresponding elemental distribution of Al;

Fig. 4. (a) XRD patterns of Al-17Mg intermediate samples with different N; (b) Magnified XRD pattern in (a); (c) Microhardness of Al-17Mg intermediate samples with different N; (d) XRD patterns of Al-Mg intermediate samples with different CMg, inset is the magnified XRD pattern in (d).

Fig. 5. Microstructure of Al-13Mg intermediate sample: (a) TEM image, inset is the SADF pattern; (b) Statistics of grain size with an average value of 85 nm; (c, d) HRTEM images of the α-Al matrix of two different areas within an Al grain after noise reduction, insets are the corresponding FFT images.

Fig. 6. HRTEM images of Al-13Mg intermediate sample: (a, b) SF and the corresponding magnified image of the red box in (a), inset in (b) is the corresponding FFT image; (c, d) 9R phase and the corresponding magnified HRTEM image of 9R phase in the red box in (c), inset in (d) is the corresponding FFT image.

Fig. 7. Microstructure of Al-13Mg intermediate sample: (a, c) HRTEM images which show solute clusters formed in different areas of the alloy, insets are the corresponding FFT images of red boxes; (b, d) Corresponding magnified images of areas marked by red boxes in (a, c) respectively; (e) HRTEM image of Al3Mg2 phase, the shape of the Al3Mg2 phase is marked by yellow dotted line; (f) Corresponding magnified image of area marked by the red box in (e); (g) HRTEM image which shows the existence of pure Mg, inset is the corresponding FFT image of the red box; (h) Corresponding magnified image of area marked by the red box in (g).

Fig. 8. (a) XRD patterns of Al-Mg final as-prepared samples with different CMg; (b) Magnified XRD patterns in (a); (c) Calculated lattice parameters of Al-Mg final samples with different CMg; (d) Measured Mg content in samples with different CMg by using different methods.

Fig. 9. Microstructure of as-prepared Al-13Mg alloy: (a) TEM image, inset is the SADF pattern; (b) Statistics of grain size with an average value of 531 nm; (c) HRTEM image of the α-Al matrix; (d) Corresponding magnified image of the red box in (c) after noise reduction, inset is the corresponding FFT image.

Fig. 10. Microstructure of as-prepared Al-13Mg alloy: (a) HRTEM image of SF; (b) Magnified HRTEM images of the red box in (a), inset is the corresponding FFT pattern; (c) 9R phase; (d) Magnified HRTEM images of the red box in (c), inset is the corresponding FFT pattern.

Fig. 11. Microstructure of as-prepared Al-13Mg alloy: (a) TEM image; (b) corresponding chemical distribution image; (c) HRTEM image of solute cluster; (d) corresponding FFT image of (c); (e) Al3Mg2 phase; (f) IFFT image and inset is the FFT image of red box in (e).

Fig. 12. Mechanical properties of as-prepared Al-Mg alloys: (a) microhardness; (b) engineering strain-stress curves; (c) work hardening rate versus true strain curves, inset is the true strain-stress curves; (d) UTS versus elongation for different Al-Mg alloys in this study.

Fig. 13. NAMLT results of as-prepared and sensitized Al-Mg alloys.

Fig. 14. UTS versus the mass loss of different Al-Mg alloy in NAMLT. CR: cold rolling; A: annealing; ST: solution treatment; H128, T6, H15, T5, T8, H321, O: different states of heat treatment. The dotted line in the figure is the dividing line susceptible to IGC.

Fig. 15. Sensitized Al-13Mg alloy: (a, c) TEM image; (b) STEM image, showing the clear grain boundary; (d) HRTME image of corresponding grain boundary in (c); (e, f) Corresponding EDS mapping images of the red box in (c).

Fig. 16. Sensitized Al-13Mg alloy: (a) STEM image; (b, c) HRTEM images of solute cluster; (d) corresponding FFT image of (c); (e) HRTME image of Al3Mg2 phase; (f) corresponding FFT image of (e).

Fig. 17. Measured yield strength and the relative contribution of different strengthening mechanisms to the strength of different Al-Mg alloys. ∆σp: contribution of precipitating strengthening; ∆σd: contribution of dislocation strengthening; ∆σgr: contribution of grain boundary strengthening; ∆σs: contribution of solid solution strengthening; σ0: the lattice friction stress in pure Al.