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In this work, three types of fully dense aluminum-based (Al) coatings (pure Al, AA2219 and AA6061) were deposited on AZ31B magnesium (Mg) alloy by a recently developed in-situ micro-forging assisted cold spray process. The detailed microstructure, coating adhesion and corrosion protection performance were systematically investigated. Results show that the porosities of the pure Al, AA2219 and AA6061 coatings are as low as 0.34 ± 0.11%, 0.23 ± 0.09% and 0.24 ± 0.08%, respectively. Strong adhesion strength (83.6–91.5 MPa) was achieved for the Al-based coatings due to the in-situ micro-forging induced enhanced mechanical-interlocking between Al-based coating and the magnesium alloy substrate. The corrosion current density of the AZ31B Mg alloy decreases to 1.9–5.8 μA cm−2 from 312.8 μA cm−2 after coated with the Al-based coatings. The long-term corrosion tests further indicate that the Al-based coatings are not aqueous solution permeable during the entire 1000 h immersion, thus provided robust long-term corrosion protection of AZ31B Mg alloy substrate. Moreover, the difference in corrosion resistances among the three Al-based coatings was observed and was further explained based on their unique microstructures arising from the coating deposition process. The present in-situ micro-forging assisted cold spray process shows great potential for economical and effective corrosion protection of magnesium alloy and provides more freedom for industries to design and use magnesium alloy parts. Image 1 • Three types of fully dense Al-based coatings were deposited on AZ31B. • Strong adhesion strength (83.6–91.5 MPa) was achieved for the Al-based coatings. • Al-based coatings possess excellent long-term corrosion protection performance. • Key factors of the different corrosion rate among the coatings were clarified. [ABSTRACT FROM AUTHOR]

The use of hematite (α-Fe 2 O 3) as anode materials remains challenging because α-Fe 2 O 3 with poor conductivity and sluggish ionic transportation in the oxide lattice during energy storage. Herein, the hierarchically structured hollow acanthospheres (Fe 2 O 3 @C-HASs), for the first time, were prepared on carbon cloth (CC) by facile solvothermal method and self-sacrifice template method. Benefiting from its unique hierarchical hollow acanthospheres structures, a large specific surface area, transition-metal oxides and graphitized carbon layer, the hierarchically structured CC/Fe 2 O 3 @C-HASs electrode delivers an outstanding areal capacitance of 1712.1 mF cm−2 at 5 mA cm−2, which are far superior to CC/Fe 2 O 3 -HASs (777.8 mF cm−2 at 5 mA cm−2). A 1.7 V flexible solid-state asymmetric supercapacitor (ASC) was successfully assembled with CC/Fe 2 O 3 @C-HASs as the anode, NiO on carbon cloth (CC/NiO) as the cathode, exhibiting a maximum volumetric energy density of 2.87 mWh cm−3 at a volumetric power density of 40.20 mW cm−3, and excellent cycling stability (82.1% after 10,000 cycles). In this work, CC/Fe 2 O 3 @C-HASs can be used as an ideal anode material, which can provide a reference for the rational design and preparation of electrode material to asymmetric supercapacitors. [Display omitted] • The hierarchical structure Fe 2 O 3 @C hollow acanthospheres possess widely distributed pores and channels. • The Highly effective conductive network constructed by carbon layer can enhance the electric conductivity and shortern charge transfer distance. • The CC/Fe 2 O 3 @C-HASs electrode exhibits a high areal capacitance and outstanding rate capability at a high mass loading. • The NiO//Fe 2 O 3 @C-HASs ASC delivers an outstanding energy density of 2.87 mWh cm−3 at a power density of 40.2 mWcm−3. [ABSTRACT FROM AUTHOR]

This study investigated the compressive behaviour of an aluminium composite. The results showed that the quasi-static stress–strain ( σ – ε ) curves of the Al composite were similar to that of Al foams. However, within the two strain ranges ε < 0.03 and ε > 0.2, the ideal energy absorption efficiency ( I ) of the composites were higher than those of Al foams. When ε ranged from 0.03 to 0.2, the I value of the composite was lower than that of Al foams. [ABSTRACT FROM AUTHOR]

Abstract: At present methods of high energy shot peening (HESP), one of the severe plastic deformation (SPD) has been used to process ultrafine-grained (UFG) (nano- and submicrocrystalline) materials. It has been found that during SPD of AZ91 magnesium alloy the structure of the surface layer develops from a cell structure to a fragmented structure with high angle misorientations and a mean grain size of 40nm. According to X-ray and transmission electron microscopy data, the nanostructure is the single phase which is the supersaturated solid solution by β-phases re-dissolution in Mg matrix. Fast diffusion during deformation is conditioned by the high stresses acting on the grain boundaries and the volumes of the fine grains. During deformation of the nanocrystalline the volume diffusion coefficient is equal to about D v =2.2×10−15 cm2/s. [Copyright &y& Elsevier]

Abstract: In this paper, the microstructures of a thin-wall die-cast commercial magnesium (Mg) alloy, aged at 200°C for various times, were investigated using transmission electron microscopy. A martensite-like phase was observed. The crystal lattice parameters of this phase are a =0.30948nm, c =0.50498nm, and axial ratio c/a =1.6314. Orientation relationship of the martensite-like phase and the parent has been determined as , and or . The driving force of the possible martensitic transformation (MT) might came from the residual microstructure stresses left during die-cast process. [Copyright &y& Elsevier]

Abstract: By means of surface mechanical attrition treatment (SMAT), a nanocrystalline (NC) surface layer about 40μm was synthesized on an AZ91D Mg alloy. The microstructural features of the surface layer produced by SMAT were systematically characterized by optical microscopy (OM) observations, X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) investigations, and hardness measurement was also carried out in order to examine the hardness variation along the depth. Experimental results show that the microstructure is inhomogeneous along the depth. In the region from top surface to about 10μm in depth, the grain size increases from about 50nm to 100nm. In the adjacent region of about 10–40μm in depth, the grain size increases from about 100nm to 400nm. The grain refinement can be attributed to the activity of dislocation and occurrence of dynamic recrystallization. Moreover, emergence of stacking faults in the grain interior is a novel discovery. After the SMAT, the micro-hardness of the surface layer was enhanced significantly compared with that of the original sample. [Copyright &y& Elsevier]

This work reveals the grain refinement process of low-stacking fault energy Cu-4wt.%Ti alloy during surface mechanical attrition treatment (SMAT). Without phase transformations, the grain refinement process in Cu-4wt.%Ti alloy with a low stacking fault energy involves formation of planar dislocation arrays and twins in the small strain and low strain rate deformed region adjacent to the coarse grain matrix, twin-twin intersections leading to grain subdivision. The formation of lamellae, polygonal grains, and rotation recrystallization were induced by the large strain and high strain rate deformation near the treated surface. We also observed one distinct layer at the treated surface with the thickness about 15 μm, which is filled with equiaxed nanograins. The hardness of the treated surface was increased by 40% and attributed to the grain refinement according to the grain boundary strengthening mechanism. [ABSTRACT FROM AUTHOR]