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Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cu-based composites under arc erosion. Exploring its influence mechanism, especially at atomic/electronic scales, is significant but challenging for the rational design of oxides/Cu contacts. Here, we designed Zn2SnO4/Cu electrical contacts aiming to solve the poor wettability of SnO2/Cu composites. It was found that Zn2SnO4 could remarkably improve the arc resistance of Cu-based electrical contacts, which was benefited by the excellent interface wettability of Zn2SnO4/Cu. The characterization of eroded surface indicated that Zn2SnO4 particles distributed uniformly on the contact surface, leading to stable electrical contact characteristic. Nevertheless, SnO2 considerably deteriorated the arc resistance of SnO2/Cu composite by agglomerating on the surface. The effect mechanism of wettability on arc resistance was investigated through density function theory (DFT) study. It revealed that strong polar covalent bonds across the Zn2SnO4/Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance. For binary SnO2/Cu interface, ionic bonds resulted in weak interface adhesion, giving rise to deterioration of electrical contact characteristic. This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials.

Correlation between precipitates evolution and mechanical properties of Al-Sc-Zr alloy with Er additions during isothermal ageing were investigated by microhardness measurements, transmission electron microscopy, atom probe tomography and density functional theory-based simulations. The results demonstrate that the Er additions significantly improve the hardness during elevated temperature ageing, especially at 400°C. This is mainly because Er additions increase the nucleation rate of the Al3(Er,Sc,Zr) precipitates, resulting in a higher density of fine and uniform dispersion of L12 structured nanoparticles. First-principles calculations demonstrate that the second nearest neighboring solute-solute interactions for the species Sc, Zr and Er are energetically favored – a key feature to rationalize the observed precipitate structure and the underlying formation mechanism. The sequential formation of the core/shell precipitates in the Er-free alloy and core/double-shell precipitates in the Er-containing alloy arises due to the different solute-solute and solute-vacancy interaction energies, and the relative diffusivities of the Er, Sc and Zr species in Al. These results shed light on the beneficial effects of Er additions on the age-hardening behavior of Al-Sc-Zr alloy and provide guidance for designing the ageing treatments for the Al-Sc-Zr(-Er) alloys.

The change of bubbles and the position of the tuyere in an oxygen coal combustion melting and separating furnace affect the flow and splash behavior of the molten pool. To analyze this problem further, a three-dimensional numerical simulation method was used to explore the behavior and change of the flow field inside the molten pool during double-row tuyere injection. In addition, the arrangement of the tuyere was changed for a more detailed understanding of the internal phase distribution and splashing in a molten pool. The results indicated that under three-dimensional numerical simulation conditions, bubbles rise after leaving the tuyere and break on the surface of the molten pool, which results in certain fluctuations in the nearby melt. During the injection process of the tuyere, the meteorological accumulation in the middle part of the molten pool formed part of the foam slag because of the influence of surface tension. When the layout of the upper and lower exhaust tuyeres was changed from staggered to symmetrical, or when the spacing of the upper and lower exhaust tuyeres changed, it had an effect on the phase distribution and splash behavior.

In the present study, the microstructure and localized corrosion behavior of three Al-Zn-Mg-X alloys with Sc addition (MSc), Cu addition (MCu) and Cu + Sc addition (MCuSc) under T74 (121 °C/6 h + 163 °C/24 h) condition have been investigated. Electron backscattered diffraction and transmission electron microscope were used to analyze the microstructure of the three alloys. Pitting corrosion, intergranular corrosion, stress corrosion cracking, ASTM B117 salt spray exposure testing, and electrochemical tests, were carried out to investigate the corrosion behavior of the three alloys. Results show that the addition of Sc and/or the removal of Cu can greatly improve the localized corrosion resistance of the Al-Zn-Mg-X alloys. The pitting corrosion in the MCu and MCuSc alloys is severer than that in the MSc alloy, which is mainly attributed to the dealloying effect occurred in the Al7Cu2Fe and Al2CuMg instead of Al3(ScxZr1-x) particles. The MSc alloy shows the highest resistance to pitting corrosion, EXCO and SCC. The modified GB features and the decreased potential difference between the GB precipitates and matrix were found to be the key factors to improve corrosion resistance of Al-Zn-Mg-X alloys. This provides a theoretical and experimental basis for the design of new Al-Zn-Mg-X alloys with excellent corrosion resistance and mechanical properties.

Developing heat-resistant conductors with high strength and high electrical conductivity is a key issue in the electrical conductor industries, as the ever-increasing power transmission poses higher requirement on the thermal stability of electrical conductor wires. Dilute Al-Sc-Zr alloys are considered as promising candidates due to the excellent heat resistance and high electrical conductivity, but the low strength always limits their application on electrical wires. Yet, few efforts on process design have been made in dilute Al-Sc-Zr alloys to enhance the strength. Here, various kinds of processing paths via combination of cold drawing, ageing and/or annealing were conducted to improve the strength and electrical conductivity of a dilute Al-Sc-Zr alloy. Results show that enhanced strength and electrical conductivity were obtained after cold drawing + ageing or pre-ageing + cold drawing + annealing treatments processes. Optimal properties (194 MPa in ultimate tensile strength and 61% IACS in electrical conductivity) were obtained through cold drawing followed by ageing. Microstructure evolution which affects strength and electrical conductivity was systematically investigated using TEM and 3DAP. The enhanced strength was mainly attributed to the suitable interactions between strain strengthening and precipitation strengthening. The enhancement in electrical conductivity was caused by precipitation of solute atoms and recovery of defects. These results provide foundations for the processing design of Al-Sc-Zr conducting wires with good properties and push forward their potential application in heat resistant conductor industries.

The addition of minor Mg (~0.4 wt%) to Al-Cu-Li alloy could not only modify the precipitation path but also promote the precipitation of T1 (Al2CuLi) phase, however, the influence of higher Mg addition on the microstructures during ageing is still not clear. In this work, the influence of high Mg addition (>0.4 wt%) on the precipitation sequence, precipitation kinetics and the corresponding strengthening of an Al-Cu-Li alloy has been investigated by atom probe tomography (APT), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and tensile testing. For an Al-Cu-Li-0.4 wt% Mg alloy in the peak-aged condition, the microstructure contains a high density of fine T1 precipitates along with some non-negligible θ' phase (Al2Cu). When adding larger amount of Mg (0.8 wt%) to the alloy, however, the precipitation of S′ phase (Al2CuMg) is strongly accelerated at the expense of T1 and θ' phases. Much more Mg clusters are observed by APT at the early ageing stages of the high Mg-containing alloy, leading to more rapid hardening response. The precipitation kinetics for T1 phase become somewhat sluggish due to decreased nucleation sites and shortage of available solutes caused by formation of more S′ precipitates. The precipitation of coarse T1 and S′ phases is significantly detrimental to the ductility and toughness in the peak-aged condition for the high Mg-containing alloy.

In van der Waals (vdWs) materials and heterostructures, the interlayers are bonded by weak vdWs interactions due to the lack of dangling bonds. The vdWs gap at the homo- or heterointerface provides great freedom to enrich the tunability of electronic structures by external intercalation of foreign ions or atoms at the interface, leading to the discovery of new physics and functionalities. Herein, the recent progress on electrochemical intercalation of foreign species into atomically thin vdWs materials for structural phase transition and device applications is reviewed and future opportunities are discussed. First, several kinds of electrochemical intercalation platforms to achieve the intercalation in vdWs materials and heterostructures are introduced. Next, the in situ characterization of electrochemical intercalation dynamics by state-of-the-art techniques is summarized, including optical techniques, scanning probe techniques, and electrical transport. Moreover, particular attention is paid on the experimentally reported phase transition and multifunctional applications of intercalated devices. Finally, future applications and challenges of intercalation in vdWs materials and heterostructures are proposed, including the intrinsic intercalation mechanism of solid ion conductors, exact identification of intercalated foreign species by near-field optical techniques, and the tunability of intercalation kinetics for ultrafast switching.

Polyimide films are widely used in space with extreme environments, where high energy beam irradiation and corresponding coupling treatment could occur. The combined effect of high energy electrons (1.2 MeV) and high tensile stress (50 MPa) on the degradation behavior of polyimide films was studied by means of scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and mechanical testing. The degradation of polyimide films was evaluated by analyzing the microstructure and mechanical properties. The results indicated that the external tensile stress and irradiation coupling treatment resulted in the breakage of a larger number of chemical bonds and greater deterioration of the surface quality when compared with the irradiated polyimide samples. After irradiation-load coupling treatment, numerous micro-cracks were formed on the polyimide surface, facilitating the diffusion of oxygen into polyimide films and thus increasing the probability of free radical reactions. Moreover, the coupling treatment led to a more significant decrease in tensile strength and elongation of polyimide films by 10% and 35%, respectively. The mechanism of molecular chains' scission and crosslinking as well as correlations between molecular chains and mechanical performances were discussed. The obtained results indicated that the external tensile stress accelerates the degradation process during electron beam irradiation; thus, the tensile stress potentially seriously deteriorates polyimide film properties in irradiated environments.

Cu-based composites are considered as one of the high performance and cost-effective materials to replace the noble metal-based electrical contact materials used in low-voltage electrical apparatus. However, the oxidation resistance of Cu-based electrical contact materials at high temperatures is still the major challenge that limits their applications. In this study, CuZr/Zn2SnO4 composites were prepared through powder metallurgy method. The air arc erosion resistance of the composites under AC 380 V and 20 A was evaluated through the mass loss and the electrical contact resistance after experienced over 10,000 arc discharge cycles. The microstructure evolution, which reflected the deterioration process of the composites, was demonstrated through SEM analysis. The results indicated that the oxidation of Zr occurred along with the oxidation of Cu at high temperature, which considerably consumed the oxygen and thus significantly enhanced the oxidation resistance of Cu-based composites. In addition, TEM result showed a smooth and clear interface between Cu and Zn2SnO4 phases, suggesting that the addition of Zn2SnO4 phases was beneficial to enhance the durability of the composite. This work will not only merit the design and development of Cu-based electrical contact materials but also expand the applications of Cu-based composites in the air at high temperature.

It is difficult to establish analytical relationships between coating parameters (type and filling ratios of absorbent) and electromagnetic (EM) properties based on traditional trial-and-error methods. Data mining is expected to predict the EM properties of coatings filled with arbitrary set type/content of absorbent based on the measured parameters within a few samples, to solve this problem. In this study, a method for predicting EM properties of coatings was established based on GA-ANN algorithm. The proposed model was found be capable of predicting EM properties of coatings, not only in wide range of filling ratio but also in case of mixed absorbents. The GA-ANN model presented lower error and higher accuracy to compare with the conventional ANN methods. Additionally, GA was used to optimize the design of coatings via using of mixed absorbent aiming to obtain broadband electromagnetic absorption (EMA) characteristics. The optimized mixture coating with the thickness of 2.06 mm contained 13.5 wt% of Co and 55.6 wt% of FeSi particles, whose effective absorption bandwidth with reflection loss less than −10 dB (ERL10) could reach 9.3 GHz.

The thermal conductivity prediction of a conductor/insulator composite with various geometrical structures of the conducting phase is one of the top challenges in disordered composites. To determine the effects of the geometrical structure of the second phase on the thermal conductivity of a conductor/insulator composite, Cu 2 O/Cu composites were prepared with spherical or branch-like Cu by hot-pressing technology. The box-counting fractal dimension was applied to characterize the geometrical structure of the second phase. The fractal dimension of branch-like Cu shows significantly lower values than the spherical Cu with a same filling content. The fractal dimension increasing rate with increasing Cu content was first introduced to predict the thermal conductivity of the composites. These results provide a pathway to determine the effects of the geometrical structure of the second phase on the thermal conductivity and shed some lights on building relationships between the tortuosity, fractal dimension, and overall performances of conductor/insulator composites.

With the development of precision instrument in space industry fields, increasing attention has been devoted to improve the dimensional stability of structural materials. In this study, the influence of quenching rate on microstructure, residual stress and dimensional stability of Al–Cu–Mg–Si alloy was studied. The results showed that boil water quenching resulted in very low residual stress but unsatisfactory mechanical properties. In contrast, low residual stress and good mechanical property were achieved by quenching the sample into 80°C water. Residual stress has a significant influence on the thermal dimensional stability. The thermal dimensional stability of sample quenched in 80°C water is better than that of sample quenched in 20°C water due to lower residual stress in 80°C water-quenched sample.

The quantitative effects of pre-treatments, namely pre-stretching and natural ageing (NA), on the precipitation sequence, precipitation kinetics and mechanical properties of an Al–Cu–Li–Mg–Ag alloy during artificial ageing were systematically investigated, aiming to elucidate the mechanisms by which these effects proceed. At the early ageing stage, pre-stretching could inhibit the formation of GP zones by restricting the Mg–Cu co-clustering, and could result in a higher nucleation rate of the T1 precipitates due to an increase in the quantity of dislocations covered by solute segregations. The introduction of NA after pre-stretching could further increase the number density of T1 by providing more nucleation sites, which evolved from the much more Mg–Ag co-clusters forming during the NA process. With prolonging ageing time, the precipitation kinetics for T1 were strongly enhanced by pre-stretching due to a more efficient nucleation of T1 and a more rapid growth rate of this phase, which was attributed to the combination of the suppression effect on the GP zone precipitation and the pipe diffusion effect derived from the introduced dislocations. When applying NA after pre-stretching, a further acceleration of the precipitation kinetics was observed, which was related to the formation of much more T1 nuclei. At the peak-aged condition, both the two pre-treatments could not only refine the precipitates but also result in a higher T1 volume fraction. Mechanisms of the strength changes induced by the pre-treatments under various ageing conditions were discussed in detail in view of these experimental results.

The structure and compositions of spinodal phases in Alnico8 alloy isothermally treated at 830 °C under external magnetic field (Hext) up to 10 T were investigated by transmission electron microscopy (TEM). Under ultra-high magnetic field (10 T), the spinodal structure of Alnico8 alloy presents interesting diversity for the shapes of α1 phase particles, namely, Π-shape, H-shape and Ш-shape apart from regular rod-shape. Composition analysis shows that the Fe was mainly distributed in the α1 phase. The Co content in the α1 phase was lower than that in the α2 phase as evidenced by the point analysis results, and Co content inα1 phase of the alloy treated without magnetic field was higher than that of the alloy treated with a magnetic field. In contrast, the Ni, Al, Cu and Ti were concentrated in the α2 phase. The average hyperfine field of the alloy treated without magnetic field was about 301.3 kOe. While the alloy treated under magnetic field, it was slightly decreased, which was about 292.0 and 296.1 kOe under 0.7 and 10 T, respectively. Magnetic properties of the alloy treated under a 10 T magnetic field were the best, which were about 1.09T, 396Oe and 9.5 kJ/m3 for Br, Hc and (BH)max respectively. Especially for the coercivity, which was mainly contributed by the anisotropy of the α1 phase induced by the high magnetic field.

The deformation microstructures near the edge of the crater of a Mg–3Al–1Zn alloy under ballistic impact with a velocity of 900 m s−1 were systematically characterized by optical microscopy (OM), scanning electron microscope (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The results show that {10 1 ¯ 2} twinning is the predominant deformation mode, and dislocation slipping also accommodates the plastic deformation with increasing strain and stress. The texture changes from basal texture to the texture close to {10 1 ¯ 0} and {2 1 ¯ 1 ¯ 0} components as it propagates from the far matrix to the crater rim, as a result of the grain reorientation caused by twinning and dislocation slipping. The stress condition and the crystallographic orientation of grains are the main factors influencing the texture evolution. Ultrafine recrystallized grains formed in the region adjacent to the crater rim which has undergone the most severe plastic deformation. The grain fragmentation induced by twin-twin interactions, together with dislocation slipping and temperature rising during plastic deformation, results in the formation of ultrafine grains at the edge of the crater. The region near the edge of the crater shows the highest microhardness due to grain refinement hardening and strain hardening.

The effects of coarse T1 phase (Al2CuLi), produced by homogenization, on the hot deformation behavior of Al–Li alloy was studied using uniaxial compression. Stress-strain curves, constitutive equations and processing maps were established, and the microstructure was observed by EBSD, SEM and TEM. The homogenized alloy with coarse T1 phase presents lower flow stresses and significantly lower deformation activation energy than the solution treated alloy. Besides, the homogenized alloy exhibits the same hot-working region with the solution treated alloy, and possesses lower power dissipation efficiencies. The EBSD investigation confirms the formation of massive recrystallized grains in the homogenized alloy at 340–460 °C, revealing the coarse T1 phase can promote dynamic recrystallization through particles stimulated nucleation. In contrast, the solution treated alloy is softened dominantly via dynamic recovery at 340–490 °C. This work not only merits the beneficial effects of the coarse T1 phase but also suggests the feasibility of obtaining accelerated recrystallization kinetic and good workability during hot working of Al–Li alloys.

In this study, residual stresses after different quenching and aging processes of Al-Cu forged blocks were investigated by numerical simulation method and experimental measurements. An iterative zone-based heat transfer calculation was coupled with the hyperbolic sine-type constitutive model to simulate the residual stress during quenching process. The simulation results were compared with experiment data using both x-ray diffraction and crack compliance methods. The simulation results were in good agreement with the experimental measurements with around 9-13% deviation at the largest. Residual stress reduction can be achieved by decreasing the cooling rate during quenching. Quenching in water with different temperatures of 60, 80, and 100 °C resulted in the maximum compressive residual stress reduction of approximately 28.2, 75.7, and 88.9%, respectively, in Al-Cu alloy samples. When quenched in 10, 20, and 30% PAG solution, the reduction of maximum compressive residual stress in Al-Cu alloy samples was approximately 35.1, 47.8, and 53.2%, respectively. In addition, in order to study the amount of residual stress relief after aging treatments, aging treatments at 140 and 170 °C for different times were also studied. Aging treatment used to obtain the peak-aged (T6) and overaged (T7) condition produces only about 22.5 to 34.7% reduction in residual stresses.

An altered surface layer forms on an Al–Zn–Mg–Cu alloy during surface preparation by abrasion with grinding paper. Strain-induced dissolution of η′/η precipitates and formation of nano-sized subgrains were observed in the surface layer with thickness of several hundred nanometers. The segregation of solute elements along dislocations and subgrain boundaries and the precipitation of Al2Cu phase at the sub-boundaries and the free surface were related to enhanced diffusion accelerated by deformation-induced vacancies, dislocations and subgrain boundaries. The microstructure evolution in this layer is mainly attributed to the shear strain and is modified by temperature rise during surface abrasion. The unique surface microstructural changes produced by abrasion might alter the surface properties.

As an energy-intensive process, aluminum production by the Hall–Heroult method accounts for significant emissions of CO 2 and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Heroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu 2 O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu 2 O/Cu was investigated in Na 3 AlF 6 –CaF 2 –Al 2 O 3 electrolyte at 960 °C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu 2 O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling content of Cu phase. The calculated corrosion rate was about 1.5–7.2 mg/сm 2 h (1.8–9 cm/y) in the current testing procedure. The Cu contents in the produced aluminum is less than 6.2 wt.%.

PbWO4 two-dimensional dendritic nanostructures (2DDNs) were prepared at room temperature through a facile aqueous solution route. X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray energy dispersive spectrometer were used to characterize the obtained samples. The PbWO4 2DDN was in one plane, with a nearly circular shape and sizes of ∼10 μm. The PbWO4 2DDNs were composed of curved nanowires around 200 nm in diameters, which were connected together to form a network nanostructure. The effects of reaction conditions including the concentration of react reagents, the reaction temperature, and the reaction time were systematically investigated and a possible formation mechanism for the formation of 2DDNs was proposed. The optical properties, such as UV–vis spectra and photoluminescence spectra of PbWO4, were studied. The advantages of this synthetic route include the first synthesis of PbWO4 2DDNs, simple synthetic procedure, room reaction temperature, and high reproducibility of the process.

Although the mechanical properties of cermet composites have been investigated extensively, how to quantitatively determine the relationship between the performances and the geometrical structures of the reinforcement phase is still one of the top challenging problems yet to be solved. To determine the influence of the geometrical structure of the reinforcement phase on the mechanical performances of composites, Cu2O/Cu cermets were prepared with spherical or branch like Cu by the hot-pressing technology. Box-counting fractal dimension increasing rate with increasing filling content of reinforcement phase was first applied to quantitatively reflect the relationship between the geometrical structures of metal phase and the mechanical properties of composites. A simple model was developed by combining fractal theory and power law, in which the critical exponents were determined via experimental results. This study not only provides a pathway to understand the mechanisms of the geometrical structure of the reinforcement phase to the mechanical properties of composites, but also sheds light on the geometrical tortuosity characterization by using fractal approach in cermet composites.

A non-isothermal ageing (NIA) process was proposed for an Al–Zn–Mg–Cu alloy aiming to accommodate heating and/or cooling procedures in large components. The precipitation was investigated systematically via TEM observation and DSC analysis. The age-hardening and the conductivity variation were examined to evaluate the potential in the strength and the corrosion resistance, respectively. Double cantilever beams (DCB) experiments were carried out to evaluate the stress corrosion cracking (SCC) resistance. A secondary precipitation occurs during the cooling procedure of the NIA process, which leads to an increase in the precipitates number density and thus induces an extra hardening. The secondary precipitation also contributes to the increase of conductivity of the alloy in the most part of the cooling procedure, but leads to a slight decrease at the terminal stage. The alloy׳s resistance to SCC improves persistently as the NIA proceeds. The evolution in microchemistry in grain boundary and adjacent regions is supposed to contribute to the improvement of corrosion resistance. The current study suggests that the NIA process (40 °C→190 °C→100 °C, 20 °C/h) is capable of enduing higher mechanical performances and comparable corrosion resistance to Al–Zn–Mg–Cu alloys, as compared with that of the T74 condition, which can be technically significant for ageing treatment of large components.

Solute segregation of Zn, Mg and Cu in and around Al3(Sc,Zr) precipitates in an Al-Zn-Mg-Cu-Sc-Zr alloy was systematically studied using atom probe microscopy, aberration-corrected scanning transmission electron microscopy and first-principles simulations. Results show that the Al3(Sc,Zr) precipitates occur as a Sc-rich ‘core’ and Zr-rich ‘shell’ structure. Zn segregates to the Zr-rich shell of Al3(Sc,Zr) precipitates and substitute mainly for the Al atoms, and the Zn segregation intensifies with increasing ageing time. Mg and Cu atoms segregate to the Zr-rich shell during the early stages of ageing, while the Mg atoms prefer the Al-matrix with longer ageing time. Density functional theory calculations demonstrate that such segregation is energetically favored and highlight the diverse role of Al3(Sc,Zr) in influencing the distribution of the major alloying elements.

We report the solvothermal synthesis of tubular BaTiO 3 nanoparticle assembly in ethanol/water mixed solvent system using Na 2 Ti 3 O 7 nanowires as template. The obtained tubular BaTiO 3 nanoparticle assembly, with a straight interior shell, is constructed by nanoparticles with diameters of 150–400 nm on the outer surface. The tubular BaTiO 3 nanoparticle assembly retains the one-dimensional characteristic inherited from the precursor Na 2 Ti 3 O 7 nanowires during solvothermal process. The formation mechanism of the hollow interior of tubular BaTiO 3 nanoparticle assembly is deriving from nanoscale Kirkendall effect, and the growth of nanoparticles on the outer surface with different sizes is controlled by the Ostwald ripening process, resulting in larger meaning outer diameter.

FeNi3/indium tin oxide (ITO) composite nanoparticles were synthesized by a self-catalyzed reduction method and a sol–gel process. The dependence of the content of ITO phase with the mole ratios of In:Sn of different sols was investigated. The relation between the electrical conductivity, infrared emissivity of FeNi3/ITO composite nanoparticles and the content of ITO phase was discussed. Electromagnetic wave absorption (EMA) performance of products was evaluated by using transmission line theory. It was found that EMA performance including the intensity and the location of effective band is significantly dependent on the content of ITO phase. The low infrared emissivity and superior EMA performance of FeNi3/ITO composite nanoparticles can be both achieved when the mole ratio of In:Sn in sol is 9:1.

Bi2WO6 hollow structures consisting of nanoparticles with diameters of 10–20 nm were synthesized by a facile and reproducible solvothermal method in the presence of ethylene glycol. The obtained Bi2WO6 hollow structures exhibit higher photocatalytic activity towards the degradation of Rhodamine B (RhB) under visible-light irradiation, up to 99% within 40 min, which was much higher than P25-TiO2. The enhanced photocatalytic performance could be attributed to their tiny building blocks as well as high BET surface areas (65.04 m2 g−1). The obtained Bi2WO6 hollow structures are chemically stable, and the efficiency remained almost the same after recycled five times, suggesting that Bi2WO6 hollow structures are promising visible-light photocatalyst for practical applications.

A lot of iron-bearing slags were produced, and whose grade is much more than that of industrial iron ore grade. Chemical analysis and phase identification shows that the iron-bearing slag is amorphous, has fayalite main phase, iron grade is 36. 10%, and is difficult to recover iron from the slag. Thermodynamic calculation indicates that CO cannot reduce fayalite at high temperature and carbon direct reduction can be effective. Moreover, the reaction begins at 770 °C and the temperature can be reduced down to 500 °C when CaO is added. On this basis, a method is put forward to making direct enrichment of iron by taking carbon contained pellets to realize the rapid reduction of fayalite, and the direct reduction process were studied in this paper. Experiments show that xc/xo should be less than 1.5 for the need of reduction and carburization, and CaO and Al2O3 can spur the reduction of fayalite. On conditions that xc/xo is 1.2, metallization rate can be 77% when temperature is 1 250 °C and only carbon is added, and metallization rate can be 74% when temperature is 1200 °C and only CaO is added. Moreover the addition of Al2O3 can get a higher metallization rate (10% or so) than usual as R is between 0. 4 and 1. 0. Under the optimized condition of R equals to 0. 6, temperature of 1 250 °C, slag melting point of 1 320 °C, and time of 30 min, the metallization rate can reach 88. 43%.

A translucent α/β Si3N4 composite, consisting of 85% α-Si3N4 and 15% β-Si3N4, was fabricated by hot-pressing at 1563 °C for 1 h, using an MgSiN2 additive. The α/β Si3N4 composite achieves a maximum transmittance of 66% for a 0.42 mm thick specimen in the medium infrared region, which is attributed to its high density and to a small amount of intergranular phase and β-Si3N4. In addition to optical transmittance, the sample showed a very high hardness of 24.0 ± 0.5 GPa.

Eu 3+ -doped CdMoO 4 red phosphor was prepared by a simple aqueous solution process at room temperature. X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy were used to characterize the phosphor. Emission and excitation spectra show that the phosphor exhibits a dominant red emission at 617 nm with excitation wavelength of 300 nm at room temperature. The red emission is visible to naked eye, indicating that CdMoO 4 is a new promising host material for the rare-earth elements. This result may bring opportunity for the generation of rare-earth element doped complex metal oxides with low cost and gram scale production.

The effects of age-forming on microstructures and mechanical properties of 7050 Al alloy were investigated in this work. The alloy was subjected to age-forming as well as stress-free ageing at 160 °C for 6, 12, 18 and 24 h, and its microstructures were characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). It was shown that creep might lead to grain elongation during age-forming, and the applied stress induces the coarsening of precipitates in 7050 Al alloy. The texture in the alloy was also influenced by age-forming. Consequently, the differences in microstructures result in differences in mechanical properties of age-forming versus traditional stress-free ageing. The ultimate tensile strength of age-formed samples were slightly lower than that of stress-free aged samples, while the yield strength of age-formed samples were apparently lower than that of stress-free aged samples. Specifically, the elongation of samples age-formed displays apparently decrease.

Plastic heterogeneities of polycrystalline aluminum during tensile test have been numerically investigated at grain level. Responses at several length scales are studied, including the overall stress, intergranular and intragranular stress–strain heterogeneities. Special attention is paid to the sensitivity of simulation with respect to the mesh refinement. The results show that, a coarse mesh containing about 500 grains is sufficient to predict the global stress–strain curve, with only one element per grain. About 5 elements per grain is enough to well describe the intergraunlar heterogeneities. However, at least 30 and 60 elements per grain should be used, in order to well describe the average deformation behavior of each grain and to capture most of the intragraunlar heterogeneities, respectively.

Adiabatic shear bands in Mg alloy under ballistic impact at a velocity of 0.5 km.s{sup -1} were characterized by means of optical microscope, scanning electron microscope, transmission electron microscope and indenter technique. The results show that adiabatic shear bands were formed around the impacted crater, and the deformed and transformed bands were distinguished by etching colors in metallographic observation. TEM observation shows that the deformed bands were composed of the elongated grains and high density dislocations, while the transformed bands composed of the ultrafine and equiaxed grains were confirmed. In initial stage, the severe localized plastic deformation led to the formation of elongated grains in the deformed bands. With localized strain increasing, the severe localized deformation assisted with the plastic temperature rising led to the severe deformation grains evolved into the ultrafine and equiaxed grains, while the deformed bands were developed into transformed bands. The formation of the ultrafine and equiaxed grains in the transformed bands should be attributed to the twinning-induced rotational dynamic recrystallization mechanism. High microhardness in the bands was obtained because of the strain hardening, grain refining and content concentration. - Research Highlights: {yields} Deformed and transformed bands are found in Mg alloy under ballistic impact. {yields}more » The microstructures in the deformed and transformed bands are characterized. {yields} The evolution process of the microstructure in the bands is discussed.« less

Flow stress behavior and microstructures during hot compression of delta-processed superalloy 718 at temperatures from 950 to 1100 °C with strain rates of 10−3 to 1 s−1 were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM). The relationship between the peak stress and the deformation conditions can be expressed by a hyperbolic-sine type equation. The activation energy for the delta-processed superalloy 718 is determined to be 467 kJ/mol. The change of the dominant deformation mechanisms leads to the decrease of stress exponent and the increase of activation energy with increasing temperature. The dynamically recrystallized grain size is inversely proportional to the Zener–Hollomon (Z) parameter. It is found that the dissolution rate of δ phases under hot deformation conditions is much faster than that under static conditions. Dislocation, vacancy and curvature play important roles in the dissolution of δ phases. The main nucleation mechanisms of dynamic recrystallization (DRX) for the delta-processed superalloy 718 include the bulging of original grain boundaries and the δ phase stimulated DRX nucleation, which is closely related to the dissolution behavior of δ phases under certain deformation conditions.

Superplasticity of the TiNp/2014AI composite prepared by powder metallurgy method was investigated by tensile tests conducted at different temperatures (773, 798, 818 and 838 K) with different strain rates range from 1·7×10° to 1·7×10−3s−1. Results show that a maximum elongation of 351% is achieved at 818 K and 3·3·10−1s−1. At different deformation temperatures, the curves of m value can be divided into two stages with the variation of strain rate and the critical strain rate is 10−1 s−1. Superplastic deformation activation energy in the TiNp/2014AI composite is 417 kJ mol−1, which is related to liquid phase formation at triple points of grain boundaries and interfaces between the matrix and the reinforcement. Superplastic deformation mechanism of the TiNp/2014AI composite is grain boundary sliding accommodate mechanism when the strain rate is lower than 10−1 s−1, and transfers to grain boundary sliding accommodation mechanism plus liquid phase helper accommodation mechanism when the strain rate is higher...

Square-shaped CdMoO 4 nanoplates with an average size of ~4 μm and thickness of ~200 nm have been successfully synthesized via a NaCl-assisted hydrothermal method without using any surfactants or templates. X-ray diffraction pattern, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy were used to characterize the samples. The formation process of CdMoO 4 nanoplates is related to NaCl, which provides a favorable chemical environment for the growth of nanoplates.

Microstructure evolution of adiabatic shear bands (ASBs) in AM60B Mg alloy impacted by a GCr15 projectile at a velocity of 500 m s −1 was studied through optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the deformed and transformed bands were formed around the crater, and the transformed bands under different etchants presented different responses, which indicated that the etching color to distinguish transformed bands was inaccurate. The ultrafine and equiaxed dynamic recrystallized grains in the transformed bands were confirmed, and twinning-induced rotational dynamic recrystallization mechanism was proposed to be responsible for the formation of the ultrafine grains in the bands. Microhardness measurements show that the microhardness in the bands was two times higher than that of the matrix, which should be attributed to the strain hardening and grain refining.

Sr0.13Na0.37Bi0.50TiO3 thin films were prepared by metalorganic solution deposition, and annealed at temperatures from 550 to 700 °C for 1–15 min. The influence of annealing on the morphology, phase and ferroelectric properties was studied by scanning electron microscopy, X-ray diffraction and ferroelectric analyzer. The doping of Na0.50Bi0.50TiO3 films with Sr results in the existence of two phases, i. e., Na0.5Bi0.5TiO3-like (matrix) phase and BiTiO3-like (second) phase, the relative contents of which depend on the annealing conditions. With the increase of annealing temperature and prolongation of annealing time, the phase content of the BiTiO3-like second phase increases and a phenocryst structure was formed, which leads to the decrease of remnant polarization of Sr0.13Na0.37Bi0.50TiO3 thin films.

Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a speed of 4 km s−1 were studied through optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and indenter technique. The results show that the deformed microstructure below the crater can be classified as three zones, i.e. dynamic recrystallization zone, high density deformation twin zone and low density deformation twin zone. The refined and equiaxed recrystallized grains adjacent to the crater were formed, which should be attributed to the twining-induced dynamic recrystallization mechanism. The { 1 0 1 ¯ 2 } , { 1 0 1 ¯ 1 } deformation twins are confirmed through selected area electron diffraction (SAED) technique. The microhardness and yield strength in the deformed microstructure zone near the crater are much higher than that of the matrix, which should be attributed to strain hardening and grain refining.

SiO2 and TiO2, as conventional dielectric shells of ferromagnetic/dielectric composite particles, can protect ferromagnetic particles from aggregation and oxidation, but contribute little to electromagnetic loss. In this work, we designed nano-assembled CoFe–CoFe2O4@C composite particles, in which ferrites with high permeability were dielectric elements and carbon was introduced as protective layers, aiming for high-efficiency microwave absorption. These assembled particles with different CoFe contents were prepared through solvothermal methods and subsequent hydrogen-thermal reduction. CoFe nanoparticles were dispersed on a CoFe2O4 matrix via an in situ reduction transformation from CoFe2O4 to CoFe. The microstructure evolution of composite particles and corresponding electromagnetic properties tailoring were investigated. The content and size of CoFe as well as the porosity of composite particles increase gradually as the annealing temperature increases. A maximum reflection loss (RL max) of –71.73 dB is observed at 4.78 GHz in 3.4 mm thick coating using particles annealed at 500 °C as fillers. The coating presents double-band absorbing characteristics, as broad effective absorption bandwidth with RL > 5 (ERL 5) and high RL max are observed in both S-C and X-Ku bands. The tunability as well as the assembled characteristic of the electromagnetic property that endued from the composite structure contributes to the excellent electromagnetic wave absorbing performances.

Au/Bi3.54Nd0.46Ti3O12/Bi2Ti2O7/Si structure has been fabricated with a preferentially (111)-orientated Bi2Ti2O7 seeding layer as a ferroelectric gate of metal-ferroelectric-insulator field effect transistor. Bi3.54Nd0.46Ti3O12 and Bi3.54Nd0.46Ti3O12/Bi2Ti2O7 films are both well-crystallized when annealed at 680°C for 40 min, and have smooth, dense and crack-free surfaces. The width of memory window of the ferroelectric gate increases with increasing electric field applied to the Bi3.54Nd0.46Ti3O12 thin films. The width of memory window of Au/Bi3.54Nd0.46Ti3O12/Bi2Ti2O7/Si with seeding layer is relatively wider than that of Au/Bi3.54Nd0.46Ti3O12/Si at the same bias voltage, and the counterclockwise hysteresis curve of Au/Bi3.54Nd0.46Ti3O12/Bi2Ti2O7/Si is referred to as polarization type switching at different voltages. Bi2Ti2O7 seeding layer plays an important role in alleviating the element interdiffusion between Bi3.54Nd0.46Ti3O12 and Si.

Ca 0.18 Na 0.32 Bi 0.50 TiO 3 (CNBT) ferroelectric thin films were prepared by metalorganic solution deposition on silicon substrate and annealed at different temperatures. The morphology and structure of the films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystal structure of Ca-doped Na 0.50 Bi 0.50 TiO 3 films shows no obvious lattice distortion compared with that of un-doped one. The optimal heat treatment process for CNBT films were determined to be high-temperature drying at 400 °C for no less than 15 min followed by annealing at 600 °C for 5 min, which leads to the formation of compact films with uniform grains of 30–50 nm. Ferroelectric property measurement shows that the remanent polarization of CNBT films is 18 times higher than that of un-doped Na 0.50 Bi 0.50 TiO 3 (NBT) thin films.

Fe/SiO2 composite particles were synthesized by hydrogen reduction of Fe2O3/SiO2 precursor, which was prepared by sol–gel method. A reduction temperature higher than 600 °C is required for the complete conversion of Fe2O3 to Fe. Fe/SiO2 composite particles exhibit superior complex permittivity and permeability in the microwave band. A reflection loss higher than − 70 dB as well as a broad absorption band can be simultaneously obtained for Fe/SiO2-based coatings about 2 mm in thickness, suggesting that the Fe/SiO2 composite particles are a promising candidate for high performance electromagnetic absorption materials.

Hot working characteristics and microstructural mechanisms of delta-processed superalloy 718 at various temperatures and strain rates were studied using the processing maps. The results show that there are two domains of dynamic recrystallization (DRX) exhibited in the map: one occurring around 1050 °C and 0.001 s−1 with a peak efficiency of 54%, and the other at 1000 °C and 0.01 s−1 with a peak efficiency of 46%. The behavior of the pre-precipitated δ phases during hot working has a great effect on the DRX of delta-processed superalloy 718. The flow instability at the strain rates higher than 0.4 s−1 is suggested to be associated with the inconsistent deformation due to the existence of the undissolved short needle-shaped δ phases.