ZnO–NiO–Co ₃ O ₄ hybrid nanoflakes are fabricated via a simple hydrothermal method followed by a subsequent annealing process.

High-temperature solid-solution is indispensable for bake-hardenable dilute Mg alloys, which generally induces grain coarsening. Herein, we report extraordinary thermal stability in a bake-hardenable dilute Mg-1.61Zn-0.57Mn-0.54Ca-0.46Al (wt. %, ZMXA2110) alloy, maintaining fine-grained structure at 450 °C. The thermal stability is stemmed from the Zener pinning effect of dense fine (∼15.0 nm) core–shell β-Mn particles and co-segregation of Zn and Ca at grain boundaries. The fine-grained (∼3.2 μm) dilute alloy exhibits high room-temperature formability in solid-solution condition with an Index Erichsen value of ∼6.0 mm, and impressive yield strength of ∼293 MPa with an evident increment of ∼60 MPa by bake-hardening treatment. GRAPHICAL ABSTRACT IMPACT STATEMENT By achieving extraordinary fine-grain thermal stability under high-temperature solid-solution treatment, appreciable bake-hardenability along with fine-grained structure are obtained simultaneously to ensure the development of dilute Mg alloys with high strength.

Forming magnesium alloys with rare earth elements (La, Gd, Nd, Y, Ce) is a routine method for modifying their microstructure and properties. In the present work, the effect of Ce addition on the microstructure evolution and the mechanical properties of as-extruded Mg-8Al-0.5Zn (AZ80) alloy was investigated. All of the extruded AZ80-xCe (x = 0, 0.2, 0.8 and 1.4 wt %) alloys exhibited equiaxed grains formed by fully dynamic recrystallization, and the grain size of the extruded AZ80 alloy was remarkably reduced by ~56.7% with the addition of 1.4 wt % Ce. Furthermore, the bulk-shaped Al₄Ce phase formed when Ce was first added, with the Ce content rising to 0.8 wt % or higher, and Al₄Ce particles in both the nano- and micron sizees were well distributed in the primary α-Mg matrix. The area fraction of the Al₄Ce particles expanded with increasing Ce content, providing more nuclei for dynamic recrystallization, which could contribute to the grain refinement. The results of the tensile tests in this study showed that Ce addition effectively improved the room temperature formability of the as-extruded AZ80 alloy, without sacrificing strength. The significantly improved mechanical properties were ascribed to excellent grain refinement, weakened texture strength, an increased Schmid factor, and a reduced area fraction of low-angle grain boundaries, all resulting from Ce addition to the as-extruded AZ80 alloy. The contribution of the nano-Al₄Ce precipitates on improving the mechanical properties was also discussed in this paper.

The surface energies of Mg₂Si (100) and (111) facets doped with modifying elements (Sb, Te, Sn, P and Bi) are calculated using first-principles methods, aimed at investigating the effects of the incorporation of modifying elements on the morphological evolution of Mg₂Si. Based on the results of surface energy, the equilibrium shape of pure Mg₂Si is predicted to be an octahedron surrounded by {111} planes. With the incorporation of Te, Sn, P and Bi, the ratio between the surface energies of the (100) and (111) planes (r) drops compared with that of pure Mg₂Si, promoting the extension of the (100) facets and the contraction of the (111) facets on Mg₂Si grains. Accordingly, the trend in morphological evolution for Mg₂Si is from the initial octahedron composed of {111} planes to a truncated octahedron surrounded by {111} and {100} planes. The results also show that Te and P are more effective in promoting the appearance frequency of (100) facets on the Mg₂Si crystal and can be used as candidate modifiers to realize the artificial manipulation of the morphology of Mg₂Si into a truncated octahedron. The findings here provide new insights for understanding the morphological evolution of Mg₂Si induced by the incorporation of modifying elements, which contributes to guiding the development of new high-temperature-resistant light alloys.