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The high-temperature steam oxidation behaviors of the four lean-Cr (7-10 wt.% Cr) FeCrAl alloys containing minor elements and the Fe13Cr4.5Al alloy without minor elements (as a reference) were systematically investigated at 1100 ℃. The cross-sectional microstructure of the products after oxidation was investigated with FIB + TEM. The results show that the oxidation kinetics of these alloys except for 7Cr alloys obeyed the sub-parabolic rate law. The ability to form a protective alumina scale was worsened by the reduction of Cr content. The content of Cr should be higher than 7 wt.% to promote alumina scale formation at 1100 ℃.

CuS nanospheres interconnected by the carbon nanotubes (CNTs) have been successfully prepared via a facile one-step microwave-assisted method. The component and microstructure of CuS/CNTs hybrid materials are well characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). Assembled as electrodes and tested in lithium ion batteries, the composites show impressive electrochemical performances. After 450 cycles, the CuS/0.1 CNT and CuS/0.5 CNT release more than 437 and 569 mAh g−1, respectively, at 400 mA g−1, which are superior to those of contrast experiments (pristine CuS and CuS mechanically mixing with CNTs). Even at the high current density of 6400 mA g−1, the CuS/0.5 CNT still displays the reversible capacity of about 400 mAh g−1. The improved performances can be ascribed to the inherently CNTs conducting network, boosting the interior electron transport and reaction kinetics, so that a significantly enhanced reversible capacities and rate capability can be realized. Furthermore, the surface properties and reaction kinetics of electrodes are also investigated via cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced lithium storage properties.

In the present work, on the foundation of Fe–13Cr-4.5Al–2Mo–1Nb-0.2Si alloy, FeCrAl alloys with low Cr content (7, 8, 9 and 10 wt%) and other minor alloying elements (Ta, Zr and Ni) were prepared. The crystal structure, microstructure, tensile properties and oxidation resistance to high-temperature steam of lean-Cr FeCrAl alloys were investigated. As with the decrease of Cr content, the matrix phase of FeCrAl alloys still exhibited the α-ferrite phase, but the lattice parameter of the matrix phase gradually increased. After annealing, the 13Cr alloy occurred complete recrystallization with an average grain size of 33.5 μm. Meanwhile, the amount of Fe2Nb-type Laves phase in FeCrAl alloys gradually decreased with the decrease of Cr content below 9 wt%. Owing to the weakest pinning effect from the small amount of Laves phase particles, many coarse equiaxed grains were observed in 7Cr alloy. 10Cr alloy did not occur full recrystallization due to relatively slow diffusion of elements resulting from the high content of alloying elements and recovered microstructure. Reducing the Cr content did not damage tensile properties of FeCrAl alloys at both room temperature and 800 °C. Due to the incomplete recrystallization, the 10Cr alloy retained higher strength and relatively poor ductility than other low Cr content alloys at room temperature. Decreasing the content of Cr made the oxidation resistance of lean-Cr alloys worse, which was still better than the traditional Zr alloy. The present work showed that small changes in Cr will not have a remarkable impact on tensile properties and oxidation resistance to high-temperature steam, and low-Cr FeCrAl alloys can be used as an accident-tolerant fuel cladding in light water reactors.

Silicon has been considered as the most promising anode candidate of new generation high-performance LIBs, but the huge volume strain during cycling processes limited its practical applications. Herein, the binder free TiO2-nanowires (NWs)-C/Si/C 3D network composite has been prepared by chemical vapor deposition (CVD) and facile carbonization process as a great solution to the problem. In this composite, the intertwined TiO2-NWs serves as a buffer matrix to alleviate the volume strain of silicon during cycling processes, while the dual protective carbon layers enhance the conductivity of TiO2-NWs and prevent Si from peeling off the substrate. The as-prepared TiO2-NWs-C/Si/C anode shows great cycling performance with a reversible capacity of 1570 mAh g−1 at 2 A g−1 and excellent capacity retention of 85.7% up to 100 cycles.

Lithium sulfur batteries have been widely studied because of their high energy density. However, their commercialization has been impeded by several problems, such as the poor conductivity of the active material sulfur and its discharge products, the volume expansion and the shuttle effect caused by the polysulfide intermediates dissolving in organic electrolytes. To address these problems well, we have constructed high sulfur content spherical sulfur-carbon nanotube-polyethylene glycol-nickel nitrate hydroxide (SCNT-PEG-NNH) composite material by using a simple ball-milling method. The conductivity of the composite material gets improvement due to the spherical conductive frame constructed by CNT, while the shuttle effect of polysulfides is well inhibited by the wrapping of the PEG and the fixation of NNH. The results of electrochemical tests have shown that the performance of cathode made by the SCNT-PEG-NNH composite material is greatly improved. Therefore, the SCNT-PEG-NNH composite material can be a promising cathode material for lithium sulfur batteries.

The lack of suitable high-voltage cathode materials has hindered the development of rechargeable magnesium batteries (RMBs). Here, mesoporous Na3V2(PO4)3/C (NVP/C) spheres have been synthesized through a facile spray-drying–annealing method, and their electrochemically desodiated phase NaV2(PO4)3/C (ED-NVP/C) has been investigated as an intercalation host for Mg2+ ions. The obtained ED-NVP/C exhibits an average discharge voltage of around 2.5 V (vs. Mg2+/Mg), higher than those of most previously reported cathode materials. In addition, it can deliver an initial discharge capacity of 88.8 mA h g−1 at 20 mA g−1, with good cycling stability. Ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results demonstrate that the electrochemical reaction is based on an intercalation mechanism and shows good reversibility. Galvanostatic intermittent titration technique (GITT) data have revealed that the intercalation process involves a two-phase transition. The reported ED-NVP/C cathode material with high working voltage offers promising potential for application in RMBs.

Although lithium-sulfur batteries are considered as promising high-energy-storage system owing to their high energy density, developing effective materials to host sulfur species on the cathode is still challenging. Herein, an inexpensive and effective carbon precursor, catechol and polyamine is explored to fabricate nitrogen/oxygen dual-doped hollow carbon nanospheres (DHCSs) as sulfur hosts. The group containing nitrogen and oxygen can provide stronger chemisorption for lithium polysulfides than single-doped carbon matrix, which is confirmed by X-ray photoelectron spectroscopy analysis and the theoretical calculation. As a result, the designed sulfur/DHCSs cathode delivers a stable cycling performance remained 851 mAh g −1 discharge capacity at 0.2 C with ∼0.08% capacity decay per cycle after 200 cycles, revealing its great promise for energy storage application.

Si is regarded as a promising anode candidate for lithium-ion batteries (LIBs) due to its high theoretical capacity and appropriate Li + ions insertion voltage ( + /Li). However, its intrinsic inferior electronic conductivity and huge volume changes during cycling lead to poor cyclic performance. Integrating Si with carbon materials has been proved to be an efficient route to improve its electrochemical performance. In this report, we successfully synthesized Si-reduced graphene oxide-amorphous carbon (Si-rGO-C) composite assisted with a facile guar gum hydrogel method and studied the protective effect of different kinds of carbon. In the Si-rGO-C ternary composite, the Si nanoparticles (NPs) are embedded in amorphous carbon and tightly anchored to rGO sheets. The amorphous carbon and rGO serve as synergistic protective layers. The Si-rGO-C composite possesses good structural integrity accompanied by enhanced conductive framework. The resulting Si-rGO-C composite exhibits much improved electrochemical performance (a high capacity of 913 mAh g −1 can be maintained after 100 cycles at 0.5 A g −1 with almost no capacity decay) compared with the Si-rGO and Si-C composites with only single protective layer, indicating the importance of constructing synergistic carbon layers in Si-rGO-C ternary composite for LIB anodes.

In this work, CuS microspheres are synthesized by a facile microwave synthesis without any template or additive. As-prepared CuS microspheres display steady reversibility by adopting triethylene glycol dimethyl ether (TEGDME) as the electrolyte solvent and adjusting cut-off voltage to 0.6 − 3.0 V. The discharge capacity stands at 162 mAh g −1 after 200 cycles with the capacity retention of 95.8%. Electrochemical kinetics of CuS electrodes is investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) tests. Beyond that, electrochemical reactions of CuS electrodes are explored using ex-situ X-ray diffraction (XRD). As far as we know, it is not only the best performance of CuS electrodes in Na-ion batteries (NIBs) but also the first time that the kinetics and reaction mechanism of CuS in NIBs are investigated.

Nanostructure construction and surface modification are effective ways to improve the electrochemical performances of electrode materials, especially for the conversion reaction-based materials. In this study, one-dimensional carbon coating bamboo-like Cu 2-x S nanorods have been delicately designed in a template-free method. The structure and morphology are well characterized via different instruments such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tested in lithium batteries as the anode, the Cu 2-x S@C electrode shows superior electrochemical performances to pristine Cu 2-x S. At 1 and 2 C, the Cu 2-x S@C nanorod electrode releases 309 and 277 mAh g −1 after 300 cycles. At high rates of 15 and 22 C, the electrode still exhibits 269 and 264 mAh g −1 . The kinetics of electrodes are also investigated by means of cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced electrochemical properties. Thus, the one-dimensional bamboo-like Cu 2-x S voided nanorods can be a promising candidate for high-performance batteries.

The lithium-sulfur battery is considered as a prospective candidate for a high-energy-storage system because of its high theoretical specific capacity and energy. However, the dissolution and shutter of polysulfides lead to low active material utilization and fast capacity fading. Electrospinning technology is employed to directly coat an interlayer composed of polyacrylonitrile (PAN) and nitrogen-doped carbon black (NC) fibers on the cathode. Benefiting from electrospinning technology, the PAN-NC fibers possess good electrolyte infiltration for fast lithium-ion transport and great flexibility for adhering on the cathode. The NC particles provide good affinity for polysufides and great conductivity. Thus, the polysulfides can be trapped on the cathode and reutilized well. As a result, the PAN-NC-coated sulfur cathode (PAN-NC@cathode) exhibits the initial discharge capacity of 1279 mAh g-1 and maintains the reversible capacity of 1030 mAh g-1 with capacity fading of 0.05% per cycle at 200 mA g-1 after 100 cycles. Adopting electrospinning to directly form fibers on the cathode shows a promising application.

Owing to their unique structural stability and impressive long-term cycling performance, coated hollow structures are highly attractive for energy storage systems, especially batteries. Many efforts have been devoted and various strategies have been proposed to prepare such materials. In the present work, we propose a self-templating thermolysis strategy, different from traditional wet processing methods, to fabricate cuprous sulfide hollow spheres coated with different shells, by exploiting the thermal decomposition properties of the core (CuS) and the protection provided by the shell. To demonstrate the generality of this synthetic approach, three different coating materials (carbon, TiO2, MoS2) have been chosen to prepare Cu2–xS@C, Cu2–xS@TiO2 and Cu2–xS@MoS2 hollow spheres. All synthesized composite materials were then assembled as electrodes and tested in lithium batteries, showing excellent cycling stability. In particular, the electrochemical properties of Cu2–xS@C were thoroughly investigated. The results of this work provide an alternative route to prepare coated metal sulfide hollow spheres for energy storage applications.

A new type of single-ion conducting polymer electrolyte, poly(hexafluorobutyl methacrylate-co-lithium allyl sulfonate) (P (HFMA-co-ASLi)) for lithium-ion batteries, was firstly prepared by copolymerizing hexafluorobutyl methacrylate (HFMA) and sodium allyl sulfonate (SAS) with a subsequent lithiation process. The prepared polymer electrolyte exhibits high lithium ionic conductivity (10-4 S cm-1 at 80 ℃) and excellent cycle performance at high temperature, which could be attributed to the good thermal stability (remains stable up to 300 ℃), mechanical property (7.1 MPa for breaking strength) and high lithium-ion transference number (0.92). The electrolyte also displays good electrochemical stability (4.6 V). Our obtained results prove that the polymer P (HFMA-co-ASLi) is a promising candidate electrolyte for lithium-ion batteries.

A rod-like Cu2−xSe is synthesized by a facile water evaporation process. The electrochemical reaction mechanism is investigated by ex situ X-ray diffraction (XRD). By adopting an ether-based electrolyte instead of a carbonate-based electrolyte, the electrochemical performance of Cu2−xSe electrodes improved significantly. The Cu2−xSe electrodes exhibit outstanding cycle performance: after 1000 cycles, 160 mA h g−1 can be maintained with a retention of 80.3 %. At current densities of 100, 200, 500, and 1000 mA g−1, the capacity of a Cu2−xSe/Li battery was 208, 202, 200, and 198 mA h g−1, respectively, showing excellent rate capability. The 4-probe conductivity measurements along with electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV) tests illustrate that the Cu2−xSe electrodes display high specific conductivity and impressive lithium–ion diffusion rate, which makes the Cu2−xSe a promising anode material for lithium–ion batteries.

Sulfur, as a cathode material in lithium−sulfur batteries, has a very high theoretical specific capacity of 1675 mAh g−1, but there is still a large challenge, because of polysulfides’ (PSs) that cause a severe shuttle effect. To suppress this effect, a simple way of modifying separator by introducing lithium fluoride (LiF) as a coating layer was developed. Owing to the interaction between LiF and dimethoxymethane (DME, an electrolyte solvent), a dense and viscous sol layer was formed that suppresses PSs passing from the cathode to the anode. The presence of this layer was confirmed by using Fourier transform infrared spectroscopy, thermogravimetric/differential thermogravimetric, and scanning electron microscopy. The linear sweep voltammetry test had shown that the LiF-coated separator had a wide electrochemical window above 5 V vs. Li/Li+, and the cell assembled with the LiF-coated separator exhibited an excellent cycling performance with a capacity retention rate of 69.3%. Even without LiNO3 as an electrolyte additive, a high coulombic efficiency of 93% after 200 cycles at 0.2 C was achieved.

Lithium-sulfur battery has received extensive attention because of its high energy density, but its practical application has been limited by several problems such as short cycle life and low efficiency. In this study, we prepare monodispersed sulfur nanoparticles (S NPs) on partially reduced graphene oxide (S-prGO) during reduction of graphene oxide by spray method. The S-prGO composite is then recombined with polydopamine (PDA) to get the S-prGO-PDA composite. The S-prGO-PDA composite exhibits great cycling stability, coulombic efficiency and capacity retention. When charge-discharge at current density of 200 mA g−1, the specific capacity is 1122 mAh g−1 at the first discharge and 647 mAh g−1 after 100 cycles, with stable coulombic efficiency of 98%.

Porous Ti-based alloys enable various orthopedic applications but they are often hindered by structure-derived stress concentration failure, low strength, poor plasticity or uncertain biosecurity caused by the extra space holder. Here, we present a radial gradient porous composite with structure-derived favorable pore characteristics achieved by designing a hierarchical porous architecture composed of a central Ti-Ag micro-pore core and an outer interconnected spherical Ti porous layer with 49% porosity as well as 105 µm average pore size. Simultaneously, the composite exhibits an exceptionally low elastic modulus (16.8 GPa) and high compressive strength (1248 MPa), together with an excellent plastic deformation ability (over 40%) owning to the eutectoid transformation: β-Ti→α-Ti+Ti2Ag and the continuous gradient structure. An combination of pore characteristics, large plasticity, low elastic modulus, high strength and favorable osteoblast affinity implies the Ti-Ag/Ti composite is a good potential candidate for orthopedic surgery and other medical applications.

Micro/nanostructured Co 9 S 8 cubes and spheres (S-Co 9 S 8 ) were successfully prepared with Co 3 O 4 as templates via the vapor-based anion exchange reaction. The morphology and structure of both materials were characterized by SEM and XRD. Co 9 S 8 microcubes and microspheres were composed of nanoparticles, inheriting the micro/nanostructure of Co 3 O 4 precursors. Tested in lithium ion batteries, C-Co 9 S 8 and S-Co 9 S 8 anodes exhibited high specific capacities, excellent cycle stability (C-Co 9 S 8 : 369 mAh g −1 , S-Co 9 S 8 : 370 mAh g −1 over 300 cycles at 1C) and high rate performances (C-Co 9 S 8 : 450 mAh g −1 , S-Co 9 S 8 : ∼430 mAh g −1 at 5C).

In recent years, the development of nuclear grade FeCrAl-based alloys with enhanced accident tolerance has been carried out for light water reactor (LWR) fuel cladding to serve as a substitute for zirconium-based alloys. To achieve excellent microstructure stability and mechanical properties, the control of precipitation particles is critical for application of FeCrAl-based alloys. In this paper, the effect of thermomechanical processing on the microstructure and precipitation behavior of hot-rolled FeCrAl alloy plates was examined. After hot rolling, the FeCrAl alloy plates had typical deformation textures. The rolling direction (RD) orientation gradually rotated from &lt, 100&gt, to &lt, 110&gt, along with increasing reduction. Shear bands and cell structures were formed in the matrix, and the former acted as preferable nucleation sites for crystallization. Improved deformation helped to produce strain-induced precipitation. The plate with 83% reduction had the most homogeneous and finest precipitation particles. Identification results by TEM indicated that the Laves precipitation was of the Fe2Nb-type crystal structure type, with impurities including Mo, Cr, and Si. The plate with uniform Laves particles displayed favorable heat stability after a long period of aging at 800 &deg, C. The microstructure evolution of the aged sample was also observed. The deformation microstructure and the strain-induced precipitation mechanism of FeCrAl alloys are discussed.

In view of developing novel alloys for applications in advanced Generation IV lead-cooled fast reactor (LFR) fuel cladding materials, four 9Cr ferrite/martensite (F/M) heat resistant steels with different Si content were developed. In the present work, the long-term thermal aging of 9Cr F/M steels was carried out in air at 550 °C for 500, 1000, 2000 and 5000 h. The microstructural evolution was investigated based on OM, SEM, EBSD and TEM technologies. The changes of mechanical properties after thermal aging were evaluated by room temperature tensile test. During long-term aging, the microstructures of all four steels exhibited highly thermal stability, and M23C6 carbides and MX carbonitrides also remained unchanged. Meanwhile, after aging for 5000 h, a new Fe2W-type Laves phase formed in all four steels with an average size of 94.8 ± 17 nm in 9Cr-1Si steel. The tensile properties of all samples aged for 2000 h exhibited almost no change compared with the as-received ones. However, after thermal exposure for 5000 h, the strength of all four 9Cr F/M steels increased due to the precipitation strengthening effect of the small Laves phase particles. Silicon exerted a certain degree of solid solution strengthening effect for 9Cr F/M steels. The volume fraction of Laves phase increased with the increase of Si content. As the Si content was 1%, residual high-temperature ferrite was found in the microstructure, but it has no detrimental effect on the mechanical properties of 9Cr F/M steels studied in the present work. Comprehensively considering the microstructure and mechanical properties, the suitable addition of Si content did not exceed 0.7%.

We report an effective double current collector electrode. In this study, we achieve a high areal loading double current collector electrode with high areal capacity density and long cycle life. We also adjust the charging condition (constant capacity charging) which leads to long cycle life with almost no capacity fading.

In this work, CuS/graphene (CuS-G) composite is synthesized via one-pot microwave irradiation method under ambient conditions. As anode material for lithium ion batteries, the CuS-G composite delivers a significantly enhanced reversible capacity and charge/discharge cycle stability compared with pristine CuS. A capacity of 348 mAh g−1 can be maintained after 1000 cycles at the current density of 2.0 A g−1. Electrochemical impedance spectroscopy (EIS) along with cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) measurements indicate that the incorporation of graphene sheets reduces the contact resistance and enhances lithium ion transfer rate during the electrochemical lithium insertion/extraction remarkably. Thus, as-prepared CuS spheres can be a promising anode material for high performance lithium ion batteries.

Silicon-multi-walled carbon nanotubes-carbon (Si-MWNTS-C) microspheres have been fabricated through the ball milling and spray drying method followed by the carbonization process. The as-prepared composite microspheres are confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The specific capacity of the as-prepared microspherical composite as anode in lithium-ion batteries (LIBs) is about 1100 mAh g−1 at the current density of 0.2 A g−1 (based on the total weight of the composite). At the high current density of 6 A g−1, the Si-MWNTS-C microspheres exhibit reversible capacity of 415 mAh g−1. Through the ex situ SEM, we observed that the Si-MWNTS-C microspherical composite particles have no extinct change on the electrode surface except for the growth of the spherical particles after 100 cycles. The excellent electrochemical performance is ascribed to the synergistic effect between Si nanoparticles (Si NPs) and MWNTS-C microspheres. The as-prepared Si-MWNTS-C microspheres can effectively accommodate large volume changes and provide a 3D conductive network during the lithiation–delithiation processes.

In this study, a facile two-step approach was developed to prepare the nanocomposites (CuxS/rGO) of copper sulfide (CuxS) microspheres wrapped with reduced graphene oxide (rGO). The morphology and structure of CuxS/rGO materials were researched by using SEM, XRD and laser Raman spectroscopy. As-prepared CuxS/rGO nanocomposites, as an active anode material in LIBs, showed distinctly improved electrochemical characteristics, superior cycling stability and high rate capability. Due to the synergistic effect between the CuxS microspheres and the rGO nanosheets, as-prepared CuxS/rGO nanocomposites could effectively alleviate large volume changes, provide a 2D conductive network and trap the diffusion of polysulfides during the discharge–charge processes, therefore, the CuxS/rGO nanocomposites showed excellent electrochemical characteristics.

Porous NiTi possesses suitable mechanical characteristics for orthopaedic implants. However, its poor bioactivity is a major challenge in the clinical application. Composite structures of porous NiTi and hydroxyapatite (HA) can be used to promote the bone ingrowth and integration of the implant with the surrounding tissue. But the differences in physical and mechanical properties of these composites are the main problem during sintering. Hence, we report a rapid fabrication of porous NiTi–HA composites using spark plasma sintering (SPS) with space holder method. Effect of HA on pore characteristics, mechanical properties and in vitro bioactivity (corrosion behaviors, ion release and apatite formation ability) of the porous NiTi–HA was investigated. Results showed that interconnected pore characteristics and 29%–37% porosity could be achieved by adding HA from 3 to 10 wt.%. Compression test revealed that porous NiTi–HA possessed not only low elastic modulus of 5.6–8.1 GPa (close to that of human bone) but also high compressive strength. Furthermore, the addition of HA could improve the bioactivity of porous NiTi significantly. The bioactivity mechanism and a relationship of HA concentration in the NiTi matrix are also discussed. The combination of interconnected pore characteristics, low elastic modulus, high strength and good bioactivity might make this material a candidate for hard tissue implants.

FeCrAl alloys have been developed as one of the promising candidates of accident tolerant fuel (ATF) cladding materials for light water reactor (LWR) to replace zirconium-based alloys. In this work, different contents of Nb (0.5, 1.0, and 1.5 wt% Nb) are doped into the Fe-13.5Cr-4.5Al–2Mo (in wt.%) alloy to develop three Nb-doping FeCrAl alloys and the Nb-free alloy is fabricated for comparison. Effects of Nb-doping content on the mechanical properties (at room temperature and 800 °C) and high-temperature (1200 °C) steam oxidation (HTSO) were investigated. Although annealing temperature increased, the grain size decreased with the increase of Nb content. The volume fraction of Fe2Nb-type Laves precipitation increased with the increment of Nb content. The strength of FeCrAl alloys at room temperature and 800 °C were both enhanced by Nb-doping. At room-temperature, Nb-doping improved the mechanical properties through grain matrix strengthening, precipitation strengthening, grain refining strengthening, and dislocation strengthening, according to the theoretical calculation analysis. On the other hand, the precipitation of the Fe2Nb phase and the solution of Nb collectively improved the yield strength of the FeCrAl alloy at 800 °C. The weight gain rate and the spallation of Al2O3 scales in high-temperature (1200 °C) steam oxidation both increased with the increment of Nb content. Discontinuous Nb oxides at the interface of Al2O3 scales and matrix formed in the Nb-doping FeCrAl alloys, which may be caused by the limited Nb content and/or Nb oxides (Nb2O5) reacted with Al2O3. Besides, Nb oxides also enhanced the stress of Al2O3 scales, resulting in the promotion of cracks and the peeling of Al2O3 scales. Last but not least, 0.5 wt% Nb content was advising for FeCrAl alloys by considering the balance of mechanical properties and HTSO.

In this study, four Fe–13Cr–4Al alloys with different Nb contents (0–1.5 wt%) were prepared by using vacuum induction melting, forging, hot rolling, and cold rolling. The effects of annealing temperature (600 °C–1100 °C) and the Nb contents on the microstructure, textures as well as tensile properties were investigated. The dispersion of fine Fe2Nb-type Laves phase particles was observed in the BCC matrix and along grain boundaries. These particles effectively pinned dislocations and boundaries, resulting in stabilizing the microstructure, delaying the recrystallization temperatures and refining the recrystallized grains. The Laves phase particles were also able to retard the nucleation and growth of the γ fiber grains, therefore Nb-containing alloys had weak recrystallized γ fibers, which was beneficial to improve the processing properties of Fe–13Cr–4Al alloys. As the annealing temperature increased, the strengths decreased while the elongation increased. Because of the effects of solid solution strengthening, precipitation strengthening and fine grain strengthening produced by the addition of Nb element, the strength and hardness of the alloys increased with the increase of Nb content. Comprehensively considering the microstructure and mechanical properties, the suitable addition of Nb content was 1 wt%, and the optimum annealing treatment after cold-rolling with 50% thickness reduction was at 700 °C for 30 min.

Transition metal sulfides are widely used in energy storage and conversion due to their exclusive physical and chemical performance. In this work, FeSx/C/CNT composites have been prepared by spray drying assisted and then calcined in an Ar atmosphere. As lithium-ion battery anodes and electrode material for supercapacitor, the FeSx/C/CNT composites display the excellent reversible capacity, capacitance and cycle stabilities. Cyclic voltammetry at different scan rates indicate that the Faraday electrochemical reaction and surface capacitance behavior occur simultaneously when the FeSx/C/CNT composites act as anode material for lithium ion battery. Cycling under 200 mA g−1 current density for 100 times, the Coulomb efficiency is still about 99% while the capacity is about 630 mAh g−1. At the current density of 1, 2, 3 and 5 A g−1, the specific capacitances of the FeSx/C/CNT composites are 617.5, 508.0, 436.1 and 365.0 F g−1, respectively. Thus, as-prepared FeSx/C/CNT composites are expected to become anode materials for high-performance lithium-ion batteries and electrode materials for high-performance supercapacitors.

The asymmetric capacitors are one of the energy storage systems that provide high energy density and high power density. However, there are some limitations which impede the development of asymmetric capacitors. In this context, we designed a new type of lithium-selenium asymmetric capacitor (LSEC) that has both the capacitive effect and the diffusion-controlled reaction. The LSECs use the activated carbon-selenium (AC-Se) as a mixed cathode material and the pre-lithiated graphite as an anode material which can exhibit the electrochemical reduction/oxidation of Se and the adsorption/desorption of anions at substantially the same rate. This novel LSEC solves the problem of imbalance between the energy and the dynamics, and provides a solution to provide both high energy density and high power density, thus has great application potential.

Fe–17Mn is a commonly used damping alloy with excellent strength, wide temperature range, and low cost. Nevertheless, its poor resistance to corrosion and its low high-temperature oxidation resistance limit its application. In this study, the high-temperature oxidation resistance was enhanced by alloying with Cr and Al. The oxidation resistance was analyzed at 500 °C. Besides, the effects of alloying with Cr and Al on the microstructure and damping capacity of Fe–17Mn alloys were also investigated. Alloying with Cr and Al changed the Ms temperature of the alloys and affected the solid phase composition. Lower Ms temperatures produced higher γ-austenite and e-martensite phase fractions. Al had a more significant effect on the reduction of the Ms temperature than Cr, because Al sharply increased the stacking faults energy that acted as a barrier for the γ → e phase transformation. Alloying with Cr and Al decreased damping capacity at low and high amplitudes. This decrement was a result of the reduction of the stacking faults probability and the e-martensite. At high amplitudes, the pinning of dislocations was the main factor deteriorating damping capacity. While Cr increased the weak pinning points, Al increased the strong pinning points. The oxidation kinetics obeyed an exponential function model, and alloying with Cr and Al significantly decreased the rate constant. The oxide scales of the Fe–17Mn binary alloy, which easily peeled off during cooling, mainly consisted of M2O3 and MnFe2O4 with several voids. The outmost of the substrate formed a ferritic layer due to the selective oxidation of Mn at high temperatures. MnO was found at the interface between the oxide scales and the ferritic layer. Although alloying with Cr and Al was not enough to form oxide scales, Cr and Al oxides dispersed in the Mn oxide scales and enriched the top of the ferritic layer hindering the inward diffusion of oxygen.

Compared with traditional lithium ion anode materials, copper sulfide has received extensive attention due to its high electrical conductivity and excellent electrochemical reversibility. However, it has poor cycle stability and rate performance under certain conditions. An important factor affecting the electrochemical performance of copper sulfide, that is, the composition of the electrolyte, has been neglected. In this work, the authors studied the effect of ether-based electrolyte composition on electrochemical performance by quasi-in situ XRD combined with XPS analysis, cyclic voltammetry and GITT tests. The results show that different electrolyte components not only affect the diffusion coefficient and overcharge behavior in the electrochemical process of copper sulfide but also affect the phase transition process.

As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni&ndash, Mo&ndash, Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe+ with peak fluence to 1.4 &times, 1014, 3.5 &times, 1014 and 7.0 &times, 1014 ions/cm2, respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe+ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe+ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed.

A process of combing use of one-step spark plasma sintering (SPS) method and space holder technique was developed to have successfully fabricated the porous NiTi alloy. To optimize porous NiTi for bone implant applications, the effects of pore characteristics and microstructures on mechanical properties and superelastic behaviors of the porous NiTi alloys were investigated by varying sintering temperatures (800–1050 °C) and ammonium hydrogen carbonate (NH4HCO3) contents (0–20 wt.%). The results showed that porous NiTi alloys with 18–61% porosity and 21–415 μm average pore size all consisted of nearly single NiTi phase with few undesired phases Ti2Ni and Ni3Ti. The superelastic recovery strain ratio of the porous NiTi alloy could be improved up to 90% through training, but with further increasing of training cycles, the curves showed an obvious ladder shaped stress plateau, which indicated the collapse of the pores. This enhanced superelasticity will greatly degrade the mechanical mismatch between bones and porous NiTi. Furthermore, with increasing the porosity and pore size, elastic modulus and compressive strength of the porous NiTi alloys decreased. However, the compressive strength was higher or close to those of human bone and the elastic modulus was close to those of human bone. The unique combination of inter-connected pore characteristics, pure phase composition, low elastic modulus, high strength and large superelastic recovery strain made this material a good candidate for ideal long-term load-bearing hard tissue implants.

This paper firstly reports a facile hydrothermal method to prepare CuFeS 2 spike-like nanorods as a promising anode material for lithium ion batteries. When being evaluated as an anode material in traditional carbonate-based (EC/DEC/DMC) and ether-based (DOL/DME) electrolytes, it's found that the type of the electrolytes plays a key role in contribution to the electrochemical performance. The CuFeS 2 binary mental sulfide material has initial discharge capacities of 632.6 mAh/g in the carbonate-based electrolyte and 674.9 mAh/g in the other at the rate of 0.2 C. After 50 circles, the discharge capacity decays severely, down to 64.3 mAh/g while the one performed in the ether-based electrolyte still possesses a capacity of 425.3 mAh/g, whose capacity retention is far more higher. Besides, an outstanding rate capability (∼190 mAh/g) can be obtained at a high rate of 10 C in the ether-based electrolyte, which is indicative of becoming promising anode materials for high-rate lithium batteries.

The lack of suitable high-voltage cathode materials has hindered the development of rechargeable magnesium batteries (RMBs). Here, mesoporous Na

The lithium-sulfur battery, which offers a high energy density and is environmental friendly, is a promising next generation of rechargeable energy storage system. However, despite these attractive attributes, the commercialization of lithium-sulfur battery is primarily hindered by the parasitic reactions between the Li metal anode and dissolved polysulfide species from the cathode during the cycling process. Herein, we synthesize the sulfur-rich carbon polysulfide polymer and demonstrate that it is a promising cathode material for high performance lithium-sulfur battery. The electrochemical studies reveal that the carbon polysulfide polymer exhibits superb reversibility and cycle stability. This is due to that the well-designed structure of the carbon polysulfide polymer has several advantages, especially, the strong chemical interaction between sulfur and the carbon framework (C-S bonds) inhibits the shuttle effect and the π electrons of the carbon polysulfide compound enhance the transfer of electrons and Li+. Furthermore, as-prepared carbon polysulfide polymer-graphene hybrid cathode achieves outstanding cycle stability and relatively high capacity. This work highlights the potential promise of the carbon polysulfide polymer as the cathode material for high performance lithium-sulfur battery.

The commercialization of sulfur cathodes has encountered several problems, including migration of polysulfide intermediates, low conductivity of sulfur and its discharge products, and volumetric changes in the cathode. To alleviate these problems, researchers have proposed a number of strategies, such as porous carriers, polysulfides sorbents, catalysts and conductive fillers. In this study, a novel CoS/C/CNT sulfur carrier material has been prepared by spray drying method to promote the performance of sulfur cathode according to the design idea of integrating various functions into one structure. The CoS/C/CNT can effectively adsorb polysulfides and catalyze their conversion. Simultaneously, the porous structure of the C/CNT conductive frame can improve the conductivity of the S-CoS/C/CNT composites, offer sufficient space to accommodate the necessary volume expansion of S and play a role in the physical limitation of polysulfides. Due to these multifunctional advantages in one structure, the obtained CoS/C/CNT shows a strong interaction with polysulfides and catalyzes the conversion of polysulfides. Finally, the obtained S-CoS/C/CNT composite cathode exhibits excellent electrochemical performance.

Nanorod-like CuS and Cu2 S have been fabricated by a hydrothermal approach without using any surfactant and template. The electrochemical behavior of CuS and Cu2 S nanorod anodes for lithium-ion batteries reveal that they exhibit stable lithium-ion insertion/extraction reversibility and outstanding rate capability. Both of the electrodes exhibit excellent capacity retentions irrespective of the rate used, even at a high current density of 3200 mA g(-1) . More than 370 mAh g(-1) can be retained for the CuS electrode and 260 mAh g(-1) for the Cu2 S electrode at the high current rate. After 100 cycles at 100 mA g(-1) , the obtained CuS and Cu2 S electrodes show discharge capacities of 472 and 313 mAh g(-1) with retentions of 92% and 96%, respectively. Together with the simplicity of fabrication and good electrochemical properties, CuS and Cu2 S nanorods are promising anode materials for practical use the next-generation lithium-ion batteries.

Abundant palynological fossils are found from the drill core in the west slope of Songliao Basin, the first full coring borehole that drilled throughout the Neogene. Two Palynological assemblages are recognized according to their vertical distributions, i.e., the late early Miocene-middle Miocene assemblage from the Da’an Formation named as Caryapollenites simplex-Momipites coryloides-Celtispollenites sp.-Tsugaepollenites igniculus, and the late Miocene-early Pliocene assemblage from the Taikang Formation named as Artemisiaepollenites minor-Betulaceoipollenites sp.-Carpinipites sp.-Polypodiace aesporites sp. On the basis of the composition of each assemblage, we infer that the climate was warm-temperate to sub-tropic during the late early Miocene-middle Miocene and the vegetation was mainly deciduous broadleaved forest and subordinate coniferous and broad-leaved mixed forest with few understory ferns, and probably some shallow fresh water wetlands. The climate then turned cooler and drier in the late Miocene-early Pliocene, represented by the development of xerophytic herbs and temperate plants, although the canopy of the forest remained relatively stable. The results significantly improve the understanding of the Cenozoic palynostratigraphy in the Songliao Basin, and provide new data for both stratigraphical correlation and paleovegetational and paleoclimatical analysis in adjacent area.

Monitoring of cyanobacteria and their toxins are traditionally conducted by cell counting, chlorophyll-a (chl-a) determination and cyanotoxin measurements, respectively. These methods are tedious, costly, time consuming, and insensitive to rapid changes in water quality and cyanobacterial abundance. We have applied and tested an online phycocyanin (PC) fluorescence probe for rapid monitoring of cyanobacteria in the Macau Storage Reservoir (MSR) that is experiencing cyanobacterial blooms. The relationships among cyanobacterial abundance, biovolume, cylindrospermopsin concentration, and PC fluorescence were analyzed using both laboratory and in-the-field studies. The performance of the probe was compared with traditional methods, and its advantages and limitations were assessed in pure and mixed cyanobacterial cultures in the laboratory. The proposed techniques successfully estimated the species including Microcystis and Cylindrospermopsis, two toxic species recently observed in the MSR. During February–November, 2010, the PC probe detected high correlations between PC and cell numbers (R 2 = 0.71). Unlike the chl-a content, which indicates only the total algal biomass, the PC pigment specifically indicates cyanobacteria. These results support the PC parameter as a reliable estimate of cyanobacterial cell number, especially in freshwater bodies where the phytoplankton community and structure are stable. Thus, the PC probe is potentially applicable to online monitoring of cyanobacteria.

With energy consumption and the development of exploitation technology of oil and gas underground, the drilling engineering has developed toward the direction of deep well, even ultra-deep well. The problem of fatigue of drill string has a great effect to drilling engineering. Strong vibration is one of the main reasons that induce drill string fatigue. In this study drill string of deep well is object being studied. The models about longitudinal vibration is set up. First, modal vibrations of drill string are studied. Then, harmonic response analysis of drill string vibration is studied. Rules of all kinds of free frequency are obtained by drilling instance. This study can offer basic method for optimizing drilling tool of deep well and drilling parameter for the purpose of reducing drill string failure.

National Science Foundation of China [50902117, 51171158, 11104126]; Fundamental Research Funds for the Central Universities of China [201212G001]; National Basic Research Program of China [2012CB933103]

The hot deformation behavior of Ni-base superalloy Rene'41 has been investigated by isothermal compression in deformation temperature range from 850 to 1050 °C with strain rates of 0.1–50 s−1 on Gleeble-3500 thermal simulation machine. The constitutive equation of the alloy is established, which describes the flow stress as a function of strain rate and deformation temperature. Based on dynamic material model and Prasad's instability criterion, the processing maps for the alloy are constructed at strains of 0.3 and 0.5. The processing map at the strain of 0.5 exhibits a single stable domain of 910–1050 °C at 0.1–1 s−1 with a peak efficiency of about 45% occurring at 0.1 s−1 and 960 °C. The dynamic recrystallization of the alloy can be easily observed at 1000 °C and 0.1 s−1. With increasing deformation temperature and/or decreasing strain rate, the volume fraction of dynamic recrystallization increases. At strains of 0.3 and 0.5, the flow instability domain mainly located at higher strain rate (>1.5 s−1). On the basis of processing map and microstructure evolution, the optimum processing conditions at the strain of 0.5 are in deformation temperature range between 950 and 1050 °C and strain rate range of around 0.1–1 s−1.

A rod-like Cu

Two boreholes drilled approximately 75 km apart in the Songliao Basin, Northeast China, have together provided a composite core that represents an almost continuous section through Late Cretaceous–early Paleocene deposits. Eight biozones have been established for this succession of seven formations based on occurrences and associations of biostratigraphically significant palynomorph genera. Seven of these suggest that there was more or less continuous deposition from the late Turonian to the early Paleocene, with the eighth encompassing a Miocene formation that overlies the succession unconformably. This zonation provides a new chronostratigraphic framework for the Late Cretaceous deposits of the Songliao Basin. The ages of most of the formations involved differ from those determined previously. One of the sedimentary units, the Mingshui Formation, includes the Cretaceous/Paleogene boundary, which seems to be indicated by an apparent “mass extinction” of palynomorph taxa, a comparatively rare occurrence outside North America. The upper Quantou Formation, the lowest unit in the succession, is dated as late Turonian–Coniacian, which is much younger than previously thought. The same applies to the overlying Qingshankou and Yaojia formations, and also to the other three (Nenjiang, Sifangtai and Mingshui) but to a lesser extent, in the conformable succession. The Early/Late Cretaceous boundary must now be located probably below the Quantou Formation, either between it and the underlying Denglouku Formation or within the latter.

The stratigraphy, age, depositional environment and correlation of the collision-related variegated sandstone and conglomerate beds exposed along the southern side of the Gangdise Mountains to the north of the Yarlung Zangbo suture in the Xigaze region, Xizang (Tibet) have been much debated. Generally referred to as the Dagzhuka Formation, these beds of great thickness have, until recently, not been reported to contain any convincing fossils. Two distinctly different palynological assemblages, indicating Late Cretaceous and Oligocene–Early Miocene ages respectively, have now been recovered from lithologically distinguishable units of the sedimentary succession at Qiabulin to the west of the town of Xigaze. This means that instead of one stratigraphic unit, as has been generally accepted hitherto, at least two are represented. As a result, the Dagzhuga Formation is considered here to refer only to the Cenozoic deposits and the Qiabulin Formation, previously regarded as a synonym, is resurrected to accommodate the Cretaceous beds. These two formations were juxtaposed by tectonic movements. Our finding indicates that the stratigraphic successions on the southern Laurasian continental margin of Xizang reflect changes from a deep forearc basin through shallow littoral environments to a mountainous landscape during the Late Cretaceous and early Cenozoic. This interpretation compares well with those documented from the Gamba and Tingri districts to the south of the Yarlung Zangbo suture.

Palaeontology plays an indispensable role in interpreting the sedimentary and tectonic history of the convergence of India and Laurasia and its consequences. Hitherto, spores and pollen grains have not been used very much in this connection. In this paper, we consider the palynology of two sedimentary successions in Xizang (Tibet) that reflect the early stages of this convergence. One of these is near the town of Xigaze, in Xigaze County (the eastern site), and the other is in Zhongba County (the western site). The palynomorph assemblages from these sites are broadly comparable in being dominated by gymnosperm pollen taxa, especially Classopollis and Exesipollenites. Angiosperm pollen grains are more common at the eastern site, especially representatives of the genus Proteacidites. The assemblages are considered to be late Late Cretaceous (SantonianeMaastrichtian) in age and, in common with the lithologies from which they were recovered, reflect a hot, arid or semi-arid climate comparable to that prevailing in South China during this period. 2007 Elsevier Ltd. All rights reserved.