Magnesium (Mg) alloys as a bioabsorbable light metal have shown great clinical potential as bone replacement implants. In this review, the categories, progress in cutting-edge preparation technologies and antibacterial mechanisms of Mg alloys and considerable numbers of corrosion-resistant and functional coatings are summarized. The relationship among the microstructure (grain size, intermetallic compounds), biocorrosion resistance and biocompatibility for antibacterial Mg alloys is discussed. The challenge and outlooks of biomedical Mg alloys and coatings are proposed from an antibacterial perspective.

At room temperature, crystalline Mg-based alloys, including Mg₂Ni, MgNi, REMg₁₂ and La₂Mg₁₇, have been proved with weak electrochemical hydrogen storage performances. For improving their electrochemical property, the Mg is partially substituted by Ce in Mg-Ni-based alloys and the surface modification treatment is performed by mechanical coating Ni. Mechanical milling is utilized to synthesize the amorphous and nanocrystalline Mg_1-xCe_xNi_0.9Al_0.1 (x = 0, 0.02, 0.04, 0.06, 0.08) + 50 wt%Ni hydrogen storage alloys. The effects made by Ce substitution and mechanical milling on the electrochemical hydrogen storage property and structure have been analyzed. It shows that the as-milled alloys electrochemically absorb and desorb hydrogen well at room temperature. The as-milled alloys, without any activation, can reach their maximal discharge capacities during first cycling. The maximal value of the 30-h-milled alloy depending on Ce content is 578.4 mAh/g, while that of the x = 0.08 alloy always grows when prolonging milling duration. The maximal discharge capacity augments from 337.4 to 521.2 mAh/g when milling duration grows from 5 to 30 h. The cycle stability grows with increasing Ce content and milling duration. Concretely, the S₁₀₀ value augments from 55 to 82% for the alloy milled for 30 h with Ce content rising from 0 to 0.08 and from 66 to 82% when milling the x = 0.08 alloy mechanically from 5 to 30 h. The alloys’ electrochemical dynamics parameters were measured as well which have maximum values depending on Ce content and keep growing up with milling duration extending.

In order to improve the interface wettability as well as the interfacial bonding between graphene and copper matrix, in this work, graphene nanoplates modified with nickel nanoparticles (Ni-GNPs) were synthesized using a one-step method based on spray-drying and chemical vapor deposition. Thereafter, 0.33 wt% Ni-GNPs were introduced into copper matrix composite by the molecular-level mixing method, leading to further enhancement of 90% in yield strength. This is attributed to the presence of Ni-GNPs, which provided high resistance to matrix against deformation. In addition, with the modification of nickel at the interface, the wettability and interfacial bonding between graphene nanoplates and copper matrix were improved, which enhanced the load transfer then. Furthermore, the microstructures and strengthening mechanisms were investigated and discussed meanwhile.

The inclination angle of the flake particle has a significant impact on the in-plane thermal conductivity of composites. The graphite flake/Al composites (50 vol%) with different inclination angles were fabricated via flake powder metallurgy, and the results show that with increasing the size of Al particle from 25.6 to 50.7 μm, the inclination angle of graphite flake decreases from 7.3° to 4.4°, while the in-plane thermal conductivity of composites increases from 473 to 555 Wm^-1 K^-1. Based on the rules of mixture, an effective model was established to qualify and quantify the relation between the inclination angle and the in-plane thermal conductivity of the corresponding composites. This model can also be applied to other flake particle-reinforced composites.

High-strength, corrosion-resistant, and lightweight Al-Mg alloys perform an important function in harsh coastal service environments. Corrosion resistance is generally inversely correlated with strength; hence, it is difficult to simultaneously optimize both. In this study, a low-magnesium Er-containing Al-based alloy that is stronger and more corrosion resistant than Al-based alloys have been reported. The alloy contains Er, and the precipitation of Al₃Er within a face-centered cubic matrix is obtained by a series of smelting-casting, heat treatment, and rolling processes. It is presumed that the strengthening phase of Al₃Er pinning dislocations improves alloy strength. It also increases the recrystallization temperature of cold-rolled matrix and induces the distribution of small-angle grain boundaries, thus allowing the alloy to achieve excellent environmental corrosion resistance. As a result, strength and corrosion resistance are simultaneously improved.

In the electromagnetic induction-controlled automated steel teeming (EICAST) technology of ladle, the height and location of the blocking layer are critical factors to determine the structure size and installation location of induction coil. And, they are also the key parameters affecting the successful implementation of this new technology. In this paper, the influence of the liquid steel temperature, the holding time and the alloy composition on the height and location of the blocking layer were studied by numerical simulation. The simulation results were verified by 40 t ladle industrial experiments. Moreover, the regulation approach of the blocking layer was determined, and the determination process of coil size and its installation location were also analyzed. The results show that the location of the blocking layer moves down with the increase in the liquid steel temperature and the holding time. The height of the blocking layer decreases with the increase in the liquid steel temperature; however, it increases with the increase in the holding time. The height and location of the blocking layer can be largely adjusted by changing the alloy composition of filling particles in the upper nozzle. When the liquid steel temperature is 1550 °C, the holding time is 180 min and the alloy composition is confirmed, the melting layer height is 120 mm, and the blocking layer height is 129 mm, which are beneficial to design and installation of induction coil. These results are very important for the industrial implementation of the EICAST technology.

In this research, 2205/Q235B clad plates were prepared by a vacuum hot rolling composite process. The effects of adding Fe, Ni, and Nb interlayers on the bonding interface structures and the shear strengths of the clad steel plates were studied. The results showed that 2205 duplex stainless steel and the three interlayers produced a large amount of plastic deformation and low-angle boundaries, and the main structures were the recrystallized and deformed grains. There were many recrystallized grains in the microstructure of the Q235B low-carbon steel due to the low deformation in the rolling process. The Fe interlayer had better wettability with the two kinds of steel, but the lower strength led to the reduction of shear strength by about 14 MPa compared with the original clad steel plate. The C element in the Q235B low-carbon steel easily diffused into the Fe interlayer, and the clad steel plate attained a poor corrosion resistance because a large decarburization area was formed. The Nb interlayer reacted with the Mo element in the 2205 duplex stainless steel to form an Nb-Mo binary alloy, which generated long-banded ferrite. The decarburization area was also produced because the Nb reacted with the C element in the Q235B to form hard and brittle NbCx. As a result, the shear strength was significantly reduced by about 282 MPa, and the corrosion resistance of the bonding surface was deteriorated. The Ni interlayer did not react with the alloy elements in both sides, and therefore effectively prevented element diffusion and improved the corrosion resistance of the bonding surface. Due to the low strength of the Ni interlayer and the increased number of bonding surfaces of the clad steel plates, the shear strength was reduced to some extent (about 40 MPa), but it still met the engineering application standards.

Hot deformation behavior of 0.3C-15Cr-1Mo-0.5N high nitrogen martensitic stainless steel (HNMSS) was investigated in the temperature range of 1173-1473 K and at strain rates of 0.001-10 s^-1 using a Gleeble 3500 thermal-mechanical simulator. The true stress-strain curves of the studied HNMSS were measured and corrected to eliminate the effect of friction on the flow stress. The relationship between the flow stress and Zener-Hollomon parameter for the studied HNMSS was analyzed in the Arrhenius hyperbolic sine constitutive model by the law of $Z = 3.76 \times 10^{15} \sinh \left( {0.004979\sigma_{\text{p}} } \right)^{7.5022}$. The processing maps at different strains of the studied HNMSS were plotted, and its flow instability regions in hot working were also confirmed in combination with the microstructure examination. Moreover, the optimal hot deformation parameters of the studied HNMSS could be suggested at T = 1303-1423 K and $\dot{\varepsilon }$ = 5-10 s^-1 or T = 1273-1473 K and $\dot{\varepsilon }$ = 0.005-0.04 s^-1.

Single-pass compression tests were performed to investigate the hot deformation behavior of low-carbon boron microalloyed steel containing three various vanadium contents at 900-1100 °C and strain rate of 0.01-10 s^-1 using the MMS-300 thermal mechanical simulator. The flow stress curves of investigated steels were obtained under the different deformation conditions, and the effects of the deformation temperature and strain rate on the flow stress were discussed. The characteristic points of flow stress were obtained from the stress dependence of strain hardening rate; the activation energy of investigated steels was determined by the regression analysis; the flow stress constitutive equations were developed; the effect of vanadium content on the flow stress and dynamic recrystallization (DRX) was investigated. The result showed that the flow stress and activation energy (316.5 kJ mol^-1) of the steel containing 0.18 wt% V were significantly higher than those of the steels with 0.042 wt% and 0.086 wt% V, which was related to the increase in solute drag and precipitation effects for higher vanadium content. DRX analysis showed that the addition of vanadium can delay the initiation and the rate of DRX.

To explore the optimum use of stabilised elements and study the influences of stabilisation in 18Cr-2Mo grades, the Nb and Nb + Ti microalloying investigation focused on the relationships of the microstructure and mechanical properties of the microalloyed 18Cr-2Mo ferritic stainless steel thick plates. Thermo-Calc calculation was performed to predict the equilibrium phase diagrams. Afterwards, the microstructure, i.e. grain size and precipitation, of as-annealed specimens was analysed by means of optical microscopy, scanning electron microscopy and transmission electron microscopy, X-ray diffraction and energy-dispersive spectroscopy. Also, electron backscatter diffraction mapping was constructed to characterise grain boundary. The mechanical properties, including tensile strength and impact toughness, were tested to correlate with the microstructure. The results show that the grain sizes of Nb-stabilised steel are comparatively smaller, which is related to the fine precipitation at the grain boundaries and beneficial to the impact toughness. The increase in its strength is not apparent due to the inhomogeneous grain sizes. The grain boundary characters are similar, which is not the main factor related to their mechanical properties. When Ti is added, TiN forms above the liquidus, and large TiN particles evidently impair impact toughness.

The application and component designs of single crystal superalloys are restricted by the precipitation of topologically closed packed (TCP) phases, which can deteriorate the microstructural stability of the alloys severely. Limited researches concerning the type and morphology evolution of TCP phases under elevated temperature conditions have been reported previously. In the present work, three Re-containing single crystal alloys were designed to investigate TCP phase evolution via long term isothermal exposure tests at 1120 °C while the effects of Re on the microstructural characteristic and elements segregation were also clarified. The results showed that the addition of Re increased the instability of the alloys and the volume fraction of the TCP phases exceeded 5 vol% when the Re content reached 3 wt%. The increasing Re content had also raised the precipitation temperature of TCP phases but it did not change the type of them after long term aging; all the TCP particles were identified as μ phase in this study. Moreover, the elements segregation became considerably serious as Re addition increased constantly, which brought about various morphologies of the μ phase in the experimental alloys. In particular, the rod-like and needle-like μ phases demonstrated the typical orientation within γ matrix while the blocky μ phase was dispersedly distributed in the space. No specific orientation relationship could be observed in the μ phase when the addition of Re exceeded certain threshold value.

To understand the atomistic mechanisms of tension failure of Ni-based superalloy, in this study, the classical molecular dynamics (MD) simulations were used to study the uniaxial tension processes of both the Ni/Ni₃Al interface systems and the pure Ni and Ni₃Al systems. To examine the effects of interatomic potentials, we adopted embedded atom method (EAM) and reactive force field (ReaxFF) in the MD simulations. The results of EAM simulations showed that the amorphous structures and voids formed near the interface, facilitating further crack propagation within Ni matrix. The EAM potentials also predicted that dislocations were generated and annihilated alternatively, leading to the oscillation of yielding stress during the tension process. The ReaxFF simulations predicted more amorphous formation and larger tensile strength. The atomistic understanding of the defect initiation and propagation during tension process may help to develop the strengthening strategy for controlling the defect evolution under loading.

Enhancing combinatorial properties, such as excellent corrosion resistance, high strength and good ductility combined, is an important issue for manufacturing high-quality AlMgSi(Cu) alloys. Here, we show that this can be achieved by optimizing a combinatorial process consisting of pre-ageing, cold-rolling and post-ageing to tailor the hierarchical microstructures of the alloy. Transmission electron microscopy analysis reveals that the enhanced combinatorial properties of corrosion resistance, strength and ductility are owing to modification of grain boundary microstructure in good association with changes of precipitate microstructures and a more homogenous distribution of solute atoms, as compared with the microstructures of the alloy processed by thermal ageing only.