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Rare earth (RE) addition to steels to produce RE steels has been widely applied when aiming to improve steel properties. However, RE steels have exhibited extremely variable mechanical performances, which has become a bottleneck in the past few decades for their production, utilization and related study. Here in this work, we discovered that the property variation of RE steels stems from the presence of oxygen-based inclusions. We proposed a dual low-oxygen technology, and keeping low levels of oxygen content in steel melts and particularly in the raw RE materials, which have long been ignored, to achieve impressively stable and favourable RE effects. The fatigue life is greatly improved by only parts-per-million-level RE addition, with a 40-fold improvement for the tension-compression fatigue life and a 40% enhancement of the rolling contact fatigue life. We find that RE appears to act by lowering the carbon diffusion rate and by retarding ferrite nucleation at the austenite grain boundaries. Our study reveals that only under very low-oxygen conditions can RE perform a vital role in purifying, modifying and micro-alloying steels, to improve the performance of RE steels.

We report magnetism of tetragonal β-Fe3Se4 nanoplates controllably synthesized by thermal decomposition at 603 K of inorganic–organic (β-Fe2Se3)4[Fe(tepa)] hybrid nanoplates (tepa = tetraethylenepentamine). (β-Fe2Se3)4[Fe(tepa)] hybrid precursor and β-Fe3Se4 nanoplates are in single crystal features as characterized by selected area electron diffraction. Rietveld refinements reveal that ordered inorganic–organic (β-Fe2Se3)4[Fe(tepa)] hybrid nanoplates are in a tetragonal layered crystal structure with a space group of I4cm (108) and room-temperature lattice parameters are a = 8.642(0) Å and c = 19.40(3) Å, while the as-synthetic tetragonal β-Fe3Se4 nanoplates have a layered crystal structure with the P4/nmm space group, and room-temperature lattice parameters are a = 3.775(8) Å and c = 5.514(5) Å. Magnetic measurements show the weak ferrimagnetism for (β-Fe2Se3)4[Fe(tepa)] hybrid nanoplates at room temperature, while the as-synthetic β-Fe3Se4 nanoplates are antiferromagnetic in a temperature range between 120 and 420 K but in a ferrimagnetic feature below ~120 K. The as-synthetic β-Fe3Se4 nanoplates are thermally instable, which are transformed to ferrimagnetic β-Fe3Se4 nanoplates by annealing at 623 K (a little higher than the synthetic temperature). There is an irreversible change from antiferromagnetism of the as-synthetic β-Fe3Se4 phase to the ferrimagnetism of the as-annealed β-Fe3Se4 phase in a temperature between 420 and 470 K. Above 470 K, the tetragonal β-Fe3Se4 phase transforms to monoclinic Fe3Se4 phase with a Curie temperature (TC) of ~330 K. This discovery highlights that crystal structure and magnetism of Fe-Se binary compounds are highly dependent on both their phase compositions and synthesis procedures.

The high activity of metallic zinc particles with water, and consequently the short pot lift of a mixed waterborne organic zinc-rich paint, are the most well-known problem for their application. In this study, zinc powders were modified by silane-crosslinked potassium silicate and the paint’s pot life was prolonged. Electron microscopy analysis showed that the zinc spheres in the waterborne paint were encapsulated by the shell consisted of silane-crosslinked potassium silicate and resin. The modification allowed the paint stay fluid after storage for 36 h. Nevertheless, the thickened shell was found to deteriorate the cathodic protection provided by the zinc particles. As a repair strategy, the post-heat treatment performing on the coating could awaken the protective effect of zinc powders. The anti-corrosion performance of the repaired coatings was confirmed by electrochemical tests and salt spray tests.

In this study, the pitting corrosion behavior of 13Cr4Ni martensitic stainless steel (BASE) and that modified with rare earth (REM) in 0.1 mol/L NaCl solution were characterized. Techniques such as automatic secondary electron microscope (ASPEX PSEM detector), scanning electron microscope (SEM), transmission electron microscope (TEM), scanning Kelvin probe force microscope (SKP), potentiodynamic and potentiostatic polarizations were employed. The results obtained indicate that BASE steel contains Al2O3/MnS, Al2O3 and MnS inclusions, while REM steels contain (La, Ce, Cr, Fe)-O and (La, Ce, Cr, Fe)-O-S inclusions. Compared with BASE steel, REM steel is more susceptible to induce the metastable pitting nucleation and repassivation, whereas it restrains the transition from metastable pitting to stable pitting. Adding 0.021% rare earth element to BASE steel can reduce the number and area of inclusions, while that of 0.058% can increase the number and enlarged the size of inclusions, which is also the reason that pitting corrosion resistance of 58REM steel is slightly lower than that of 21REM steel. In the process of pitting corrosion induced by Al2O3/MnS inclusions, MnS is preferentially anodic dissolved, and also the matrix contacted with Al2O3 is subsequently anodic dissolved. For REM steels, anodic dissolution preferentially occurs at the boundary between inclusions and matrix, while (La, Ce, Cr, Fe)-O inclusions chemically dissolve in local acidic environment or are separated from steel matrix. The chemically dissolved substance (La3+ and Ce3+) of (La, Ce, Cr, Fe)-O inclusions are concentrated in pitting pits, which inhibits its continuous growth.

The stability of catalysts in dry reforming of methane (DRM) is a known issue. In this paper an encapsulation strategy has been employed to improve the stability compared with conventional impregnation methods. Herein, nickel nanoparticles encapsulated in silicalite-1 were prepared using a range of methods including post treatment, direct hydrothermal and seed-directed methods to investigate the effect of synthesis protocol on the properties of catalysts, such as degree of encapsulation and Ni dispersion, and anti-coking/-sintering performance in DRM. The Ni@SiO2-S1 catalysts obtained by the seed-directed synthesis presented the full encapsulation of Ni NPs by the zeolite framework with small particle sizes (∼2.9 nm) and strong metal-support interaction, which could sterically hinder the migration/aggregation of Ni NPs and carbon deposition. Therefore, Ni@SiO2-S1 showed stable CO2/CH4 conversions of 80% and 73%, respectively, with negligible metal sintering and coking deposition (∼0.5 wt%) over 28 h, which outperformed the other catalysts prepared. In contrast, the catalysts developed by the post-treatment and ethylenediamine-protected hydrothermal methods showed the co-existence of Ni phase on the internal and external surfaces, i.e. incomplete encapsulation, with large Ni particles, contributing to Ni sintering and coking. The correlation of the synthesis-structure-performance in this study sheds light on the design of coking-/sintering-resistant encapsulated catalysts for DRM.

In this work, the corrosion behavior of medium-carbon steels (45, 45Cu and 45Cuq steels) in acidic chloride environment was investigated. The results indicated that the micro-galvanic effect between the anodic ferrite matrix phase and the cathodic cementite secondary phase notably affected the corrosion resistance of the three steels. For 45 steel, serious pitting corrosion happened in and around the pearlite regions, and a large number of lamellar cementite was fixed in the corrosion pits. Meanwhile, the continuously increasing superficial area of cathodic cementite enhanced the micro-galvanic corrosion, resulting in a rapidly increase in corrosion rate with time. While for 45Cu and 45Cuq steels, macroscopic uniform corrosion occurred, and the cementite accumulation was markedly reduced as compared with 45 steel, thus the micro-galvanic effect was weakened and the corrosion rate was decreased accordingly. Among these, 45Cuq steel showed the most stable and excellent corrosion resistance during long-term corrosion, indicating the occurrence of a synergistic effect between cementite spheroidization and Cu alloying, thereby significantly improving the corrosion resistance of 45 steel.

Recently, the eutectic high-entropy alloy (EHEA), AlCoCrFeNi2.1, can reach a good balance of strength and ductility. The dual-phase alloy exhibits a eutectic lamellar microstructure with large numbers of interfaces. However, the role of the interfaces in plastic deformation have not been revealed deeply. In the present work, the orientation relationship (OR) of the interfaces has been clarified as the Kurdjumov-Sachs (KS) interfaces presenting 111 B 2 | | 110 F C C and 110 B 2 | | 111 F C C independent of their morphologies. There exist three kinds of interfaces in the EHEA, namely, (321)B2||(112)FCC, (01 1 ¯ )B2||(33 2 ¯ )FCC, and (23 1 ¯ )B2||(552)FCC. The dominating (321)B2||(112)FCC interface and the secondary (01 1 ¯ )B2||(33 2 ¯ )FCC interface are both non-slip planes and atomistic-scale faceted, facilitating the nucleation and slip transmission of the dislocations. The formation mechanism of the preferred interfaces is revealed using the atomistic geometrical analysis according to the criteria of the low interfacial energy based on the coincidence-site lattice (CSL) theory. In particular, the ductility of the dual-phase alloy originates from the KS interface-induced slip continuity across interfaces, which provides a high slip-transfer geometric factor. Moreover, the strengthening effect can be attributed to the interface resistance for the dislocation transmission due to the mismatches of the moduli and lattice parameters at the interfaces.

The corrosion behavior of the as-received steel and the spheroidized steel in acidic chloride environment was investigated. The results indicate the corrosion mode and corrosion rate of two steels are diverse due to their difference in microstructure. For as-received steel with ferrite-pearlite microstructure, severe localized corrosion happens on the pearlite regions, and plenty of cathodic cementite remains in the pits, further strengthening the micro-galvanic effect and accelerating the corrosion rate. While for spheroidized steel with tempered martensite microstructure, the nanosized cementite particles evenly distributed on the ferrite substrate are easy to fall off, which can significantly reduce the cementite accumulation on the steel surface, relieving the acceleration effect of micro-galvanic corrosion.

Understanding the interface between strengthening precipitates and matrix in alloys, especially at the atomic level, is a critical issue for tailoring the precipitate strengthening to achieve desired mechanical properties. Using high-resolution scanning transmission electron microscopy, we here clarify the semi-coherent interfaces between the matrix and long-period stacking ordered (LPSO) phases, including 18R and 14H, in Mg–Zn–Y alloys. The LPSO/Mg interface features the unique configuration of the Shockley partial dislocations, which produces a near zero macroscopic strain because the net Burgers vectors equal zero. The 18R/Mg interface characterizes a dissociated structure that can be described as a narrow slab of 54R. There are two dislocation arrays accompanied to the 18R/54R and 54R/Mg interface, resulting a slight deviation (about 2.3°). The 14R/Mg interface exhibits the dislocation pairs associated with solute atoms. We further evaluate the stability and morphology of the corresponding interfaces based on elastic interaction, via calculating the mutual strong interactions between dislocation arrays, as well as that between the dislocations and solute atoms. The synchronized migration of interfacial dislocations and solute atoms, like move-drag behavior, dominates the lateral growth of LPSO phases in Mg alloys.

The precipitation behavior of different phases in a high-silicon stainless steel (6 wt% Si) during aging at 600–1050 °C for 24 h was investigated. The morphology, crystal structure and composition of various precipitates were detailly characterized using optical microscopy, scanning electron microscopy and transmission electron microscopy. Four phases were mainly identified: χ-phase, M6C carbides, σ phase and a new type of fcc-phase. During aging at 600–900 °C, the main precipitate was (Cr, Mo and Si)-rich χ-phase which was directly precipitated from γ matrix. The χ-phase was calibrated as bcc structure with a lattice parameter of 8.90 A. The peak temperature for the precipitation of χ-phase was 800 °C, and it was dissolved when aging at temperatures above 1000 °C. The σ-phase was observed only at 700 °C and grew next to χ-phase. Above 700 °C, a new fcc-phase was found to be precipitated along with χ-phase, with a space group of Fd3c and a lattice parameter of 12.56 A. The M6C carbides started to be precipitated at 700 °C in the vicinity of χ-phase. And its amount basically increased with the increasing of temperature. An orientation relationship between M6C/γ was found: [100]c//[100]γ, (001)c//(001)γ, i.e., the cube-on-cube relationship.

A spinodal decomposition is often carried out in the austenite-ferrite duplex stainless steel Fe20Cr9Ni during long-term service at a temperature in the range from 280 to 320°C, resulting in a decrease of pitting corrosion resistance. Fe-rich α phase rather than G-phase has been suggested as the major reason for the deterioration in pitting corrosion resistance of the thermally-aged steel. Here, we found that ∼76.8% of the decline in pitting resistance for the duplex stainless steel Fe20Cr9Ni was attributed to G-phase, and ∼23.2% to Fe-rich α phase after the spinodal decomposition. In this study, a suitable thermal aging treatment was introduced to obtain a larger size of the G-phase and to study the role of the phase in the corrosion process. Through immersing thermally-aged TEM specimen treated at 475°C for 3000 h in NaCl solution, the preferential position of corrosion pits formed in the ferrite was obtained. The composition changes and strain field distribution around the G-phase were analyzed by TEM-EDS, 3DAPT and GPA techniques. We further found that, although the concentration difference of Cr element between α and α’ phases was as high as 60 at.%, corrosion pits were initiated at the interface between the G-phase and the ferrite matrix rather than in the Fe-rich α phase, indicating that the Cr-depleted theory could not explain the aforesaid phenomenon. The strain energy at the interface between the G-phase and the ferrite matrix was found to be the largest. The atoms at the interface have higher energy than in the intracrystalline, and thus easily react with Cl− ions in the solution to form pits finally.

Amorphous Al2O3-reinforced Al composite (am-Al2O3/Al) compacted from ultrafine Al powders for high-temperature usages confronts with drawbacks because crystallization of am-Al2O3 at high temperatures will result in serious strength loss. Aiming at this unsolved problem, in this study, high-temperature Al materials with enhanced thermal stability were developed through introducing more thermally stable nano-sized particles via high-temperature pre-treatment of ultrafine Al powders. It was found that the pre-treatment at ≤ 550 °C could introduce a few Al2O3 in the Al matrix and increase the strength of the composites, but the strength was still below that of am-Al2O3/Al because without being pinned firmly, grain boundaries (GBs) were softened at high temperature and intergranular fracture happened. When the pre-treatment was carried out at 600 °C, nitridation and oxidation processes happened simultaneously, producing large numbers of intergranular (AlN + γ-Al2O3) particles. GB sliding and intergranular fracture were suppressed; therefore, higher strength than that of am-Al2O3/Al was realized. Furthermore, the (AlN + γ-Al2O3)/Al exhibited more superior thermal stability compared to am-Al2O3/Al for annealing treatment at 580 °C for 8 h. Therefore, an effective way to fabricate high-temperature Al composite with enhanced thermal stability was developed in this study.

(B4C+Al2O3)/Al composite designed for the dry storage of spent nuclear fuels was fabricated and then subjected to friction stir welding, at a welding speed of 100 mm/min and rotation rates of 400–800 r/min. Sound joints were obtained under all welding parameters; however, significant softening occurred in the nugget zone (NZ) for all the joints. Therefore, all the joints exhibited significantly decreased strength at both room temperature and high temperature compared with the base metal, with the joints fracturing in the NZs. Rotation rate exhibited no obvious effect on the tensile strength of the joints, but led to increased elongation as the result of the broadened NZs. The detailed microstructural examinations indicated that the welding thermo-mechanical effect broke up the near 3D amorphous Al2O3 netlike structure distributed at the Al grain boundaries, caused the coarsening of Al grains, and the agglomeration and crystallization of amorphous Al2O3, thereby resulting in the softening of the NZs and the reduction in the joint strength. Consequently, inhibiting the breakup and crystallization of 3D amorphous Al2O3 netlike structure is the key factor to improve the joint strength of the (B4C+Al2O3)/Al composite.

This work presents a two-step method for preparing structured Cobalt-Manganese Oxides nano-sheet (CMO) on SiC nano-whisker (SNW) modified SiC foam support (i.e. CMO@SNW@SiC) and its application to catalytic combustion of toluene. Firstly, SiC nano-whiskers were synthesized on the surface of SiC foam via carbothermal reduction to increase the specific surface area of the resulting structured support (SNW@SiC). Then, CMO were grown on SNW@SiC by hydrothermal synthesis. SNW@SiC provide more surface area, and the nano-sized SiO2/SiCxOy layer on the surface of the SNW promotes the redox reaction of the reactants on the surface, thereby ensuring the directional growth of CMO on SNW@SiC. Compared to the bare SiC foam, CMO loading was increased 67.5% on SNW@SiC. Analysis methods such as H2-TPR, O2-TPD and XPS prove that the redox ability of the CMO on SNW is similar to that of the powder CMO. Toluene catalytic combustion was used as a probe reaction to evaluate catalytic activity. The results show that the CMO@SNW@SiC catalyst could lower the light-off temperature compared to the CMO supported on SiC foam catalyst, which was equivalent to the bulk catalyst (CMO-24h). At the same time, in comparison with the bulk CMO catalyst, the CMO@SNW@SiC catalyst possessed a higher geometric external surface area, which promoted complete conversion of toluene at lower temperatures. In addition, the stability test shows that the CMO@SNW@SiC catalyst also had very good thermal stability and hydrothermal stability as well. The work provided not only the highly performed catalytic oxidation catalyst, but also presented a generic strategy for improving the design of structured catalysts.Keywords: structured catalyst; porous SiC foam; SiC nano-whiskers; cobalt-manganese oxides; catalytic combustion

Parkinson disease (PD) is the second most progressive neurodegenerative disorder of the central nervous system (CNS) in the elderly, causing motor impediments and cognitive dysfunctions. Dopaminergic (DA) neuron degeneration and α-synuclein (α-Syn) accumulation in substantia nigra pars compacta (SNPc) are the major contributor to this disease. At present, the disease has no effective treatment. Many recent studies focus on identifying novel therapeutics that provide benefits to stop disease advancement in PD patients. Cannabidiol (CBD) is a cannabinoid derived from the Cannabis sativa plant and possesses anti-depressive, anti-inflammatory, and antioxidative effects. The present study aims to evaluate the neuroprotective effect of CBD in transgenic C. elegans PD models. We observed that CBD at 0.025 mM (24.66 %), 0.05 mM (52.41 %) and 0.1 mM (71.36 %) diminished DA neuron degenerations induced by 6-hydroxydopamine (6-OHDA), reduced (0.025, 27.1 %), (0.05, 38.9 %), (0.1, 51.3 %) food-sensing behavioural disabilities in BZ555, reduced 40.6 %, 56.3 %, 70.2 % the aggregative toxicity of α-Syn and expanded the nematodes' lifespan up to 11.5 %, 23.1 %, 28.8 %, dose-dependently. Moreover, CBD augmented the ubiquitin-like proteasomes 28.11 %, 43.27, 61.33 % and SOD-3 expressions by about 16.4 %, 21.2 %, 44.8 % in transgenic models. Further, we observed the antioxidative role of CBD by reducing 33.2 %, 41.4 %, 56.7 % reactive oxygen species in 6-OHDA intoxicated worms. Together, these findings supported CBD as an anti-parkinsonian drug and may exert its effects by raising lipid depositions to enhance proteasome activity and reduce oxidative stress via the antioxidative pathway.

Ethyl lactate is a promising green solvent, which can be produced via esterification of biomass derived lactic acid and ethanol. Herein, we report the development of highly active and stable polyoxometalates (POMs) supported on zeolite catalysts for synthesis of ethyl lactate. Repetitive stability tests were performed using the developed catalysts, and comparative characterization of the fresh and used catalysts was performed to understand the changes in the physicochemical properties of the catalysts. It was found that low-silica Y zeolites (silicon-to-aluminum ratio, SAR, of 2 and 5) are prone to be dealuminated (by lactic acid) under the reaction conditions, and thus being not suitable to be used as the catalyst support. Direct support of 12-tungstophosphoric acid (by impregnation) on high-silica Y zeolite (SAR40) led to deactivation during catalysis due to 12-tungstophosphoric acid leaching. This issue was solved by surface modification of the high-silica Y zeolite using cesium (Cs) ions before impregnation of 12-tungstophosphoric acid because the formed cesium phosphotungstate is insoluble in the reaction. As a result, a stable composite catalyst of Cs exchanged 12-tungstophosphoric acid supported on high-silica mesoporous Y was developed, which showed good reusability. In detail, after seven cyclic tests, the physiochemical properties of the catalyst and the catalytic performance remained relatively stable, e.g., the yield of ethyl lactate remained at around 29.6%. Findings of the study show that the stability of the zeolitic support and the support heteropolyacid are equally important for obtaining a stable catalyst for ethyl lactate synthesis via esterification.

B4C particulate-reinforced 6061Al composite was fabricated by powder metallurgy method. The as-rolled composite possesses high tensile strength which is comparable to that of the peak-aged 6061Al alloy. More importantly, the microstructures and mechanical properties are thermally stable during long-term holding at elevated temperature (400 °C). The microstructual contributions to the strength of the composite were discussed. Transmission electron microscopy (TEM) analysis indicates that the in-situ formed reinforcement Mg(Al)B2, as products of the interfacial reactions between B4C and the aluminum matrix, show not only good resistance to thermal coarsening but also strong pinning effect to the grain boundaries in the alloy matrix.

γ′-Strengthened Co-base single crystal superalloy was jointed with B-Ni76CrWB alloy powder by transient liquid phase bonding. The growth mechanism of the borides of preferred orientation formed in the diffusion affect zone of the joint was investigated. Results indicated that the prepared borides were (Co,W,Ta)3B2 and were long plate-shaped in three dimensions. The preferred growth orientation of the borides in the diffusion affect zone of transient liquid phase joint was 〈0 0 1〉 matrix, enjoying a significant orientation relationship with the substrate.

In this work, we investigate the tensile strength and ductility of bulk Cu/Nb nanolaminates after exposure to high temperatures. We show that the interface transforms from flat to wavy at a transition temperature of 700 °C, and tensile strength is linearly proportional to H-1/2 (H = layer thickness). Moreover, the wavy interfaces give rise to a higher slope of the Hall-Petch law. This result can be attributed to greater resistance to slip transmission across wavy interfaces compared to planar interfaces. After 1000 °C for 1 h, the material still exhibits a high strength of 468 MPa and enhanced elongation.

Titanium with hexagonal close-packed (hcp) structure can undergo phase transformation to face-centered cubic (fcc) structure under mechanical straining at room temperature. In this work, we identified two orientation relationships (ORs) between fcc phase and hcp matrix in commercial pure Ti, i.e., P-type OR [ 1 ¯ 2 1 ¯ 0]hcp||[1 1 ¯ 0]fcc and (10 1 ¯ 0)hcp||(110)fcc, and B-type OR [ 1 ¯ 2 1 ¯ 0]hcp||[1 1 ¯ 0]fcc and (0001)hcp||( 1 ¯ 1 ¯ 1)fcc. The P-type interface is flat while the B-type interface is stepped, which are ascribed to the pure-shuffle mechanism and the partial gliding mechanism, respectively. Most intriguingly, the B-type fcc lamella can penetrate the P-type fcc lamella through gliding of the dislocation with Burgers vector ½[110] on (001)fcc plane.

High entropy alloys (HEAs) have presented potential applications in nuclear power plants owing to their novel atomic structure based high irradiation resistance. However, understanding of He-ion irradiation of HEAs is still lacking. In this work, we reveal He-ion irradiation resistance of HEA CrMnFeCoNi by comparison study with a pure Ni and a 304 stainless steel (304SS). It is found that the damage structure in the three materials can be characterized with He bubbles and stacking faults/stacking fault tetrahedrons ((SFs/SFTs), which show a similar depth distribution after He-ion irradiation at both RT and 450 °C. Although the He bubbles have a similar size about 2 nm after irradiation at RT, the He bubble sizes of the HEA, 304SS, and Ni increase to 4.0 ± 0.9, 5.3 ± 1.0 and 6.7 ± 1.0 nm after irradiation at 450 °C, respectively. Moreover, the density of SFs/SFTs displays in an order of Ni

Generally, minor elements such as carbon and boron are added in superalloys to strengthen grain boundaries. However, effects of carbon and boron on single crystal superalloys remain disputed. Here we demonstrate that M23B6 (where M is mixture of W, Mo, Cr and Ni) can induce dislocation channeling in a Ni-based single crystal superalloy. The M23B6 has a cube-on-cube orientation relationship with the matrix, forming a majority of {1 1 1} plane interfaces. Furthermore, the atomic stepped {1 1 1} interface could facilitate dislocation nucleation. Dislocations emitted from the interface glide forward and pile-up in the channel, resulting in strain localization and creep micro-crack initiation.

ZSM‐5 zeolite nanoboxes with accessible meso‐micro‐pore architecture and strong acid sites are important in relevant heterogeneous catalysis suffering from mass transfer limitations and weak acidities. Rational design of parent zeolites with concentrated and non‐protective coordination of Al species can facilitate post‐synthetic treatment to produce mesoporous ZSM‐5 nanoboxes. In this work, a simple and effective method was developed to convert parent MFI zeolites with tetrahedral extra‐framework Al into Al‐enriched mesoporous ZSM‐5 nanoboxes with low silicon‐to‐aluminium ratios of ≈16. The parent MFI zeolite was prepared by rapid ageing of the zeolite sol gel synthesis mixture. The accessibility to the meso‐micro‐porous intra‐crystalline network was probed systematically by comparative pulsed field gradient nuclear magnetic resonance diffusion measurements, which, together with the strong acidity of nanoboxes, provided superb catalytic activity and longevity in hydrocarbon cracking for propylene production., ZSM‐5 nanoboxes with low SARs: Rapid ageing of a sol gel synthesis mixture produces a parent zeolite with tetrahedral extra framework Al and a low silicon‐to‐aluminium ratio (SAR) value of ≈12, which is transformed to mesoporous ZSM‐5 nanoboxes with low SARs of ≈16 during post‐synthetic TPAOH treatment. The mesoporous ZSM‐5 nanoboxes show comparatively enhanced mass transfer ability, catalytic cracking activity and longevity.

In this work, titanosilicate MFI (TS-1) crystals with different Si/Ti ratio were treated with tetrapropylamonium hydroxide (TPAOH) solution of different concentrations. The results showed that the properties – crystal structure, titanium position, secondary pore structure and volume – of the treated samples strongly depend on the Si/Ti ratio of the parent TS-1 sample and the TPAOH concentration. For instance, high TPAOH concentration is necessary to induce titanium re-insertion into framework position and to create inter-connected open meso/macropore in TS-1 with low Si/Ti ratio. On the contrary, TPAOH treatment even at high concentration was found to be ineffective in the post-synthesis treatment of low titanium containing TS-1 samples and result in a phase change from orthorhombic to monoclinic. The post-treated high titanium containing and inter-connected secondary pore TS-1 samples exhibited higher activity for cyclohexene epoxidation than the parent TS-1 sample with similar Si/Ti. This technique provides a controlled way of mesopore creation in TS-1 materials, which may be extended to other titanium base microporous materials.

ε-Iron nitrides with the general formula ε-Fe3N1+x (-0.40x0.48) have been widely studied due to their interesting magnetism. However, the phase diagram of the Fe-N binary system indicates the absence of monophasic ε-Fe3N1+x (x0) compounds that are stable below their synthetic temperatures. Here, ε-Fe3N1+x (-0.12 ≤ x ≤ -0.01) nanoparticles with excellent thermal stability and magnetic properties were synthesized by a simple chemical solution method. The ε-Fe3N1+x nanoparticles with space group P6322 have excellent oxidation resistance due to a carbon shell with a thickness of 2-3 nm. NPD refinements suggest that the ε-Fe3N1+x nanoparticles possess a highly ordered arrangement of N atoms and their magnetic moments align parallel to the c axis. The Curie temperature (TC) and room temperature saturation magnetization (MS) increase with decreasing N content, which results in record-high TC (632 K) and MS (169.2 emu g-1) at x = -0.12, much higher than the magnetic properties of the corresponding bulk materials. The significant enhancements in the intrinsic magnetic properties and thermal stability of ε-Fe3N1+x are ascribed to chemically engineering the stoichiometry and N occupancy from the disordered to the ordered site.

Faujasite (FAU) Y zeolite assemblies with high mesoporosity (Sext. = 347 m2 g−1 and Vmeso = 0.52 cm3 g−1) were synthesised using sustainable and economic cellulose nanocrystals (CNCs) via a template-directed synthesis method, i.e. CNCs-Y. In comparison with the control zeolite catalysts of the conventioanl microporous Y and carbon nanotubes templated Y (CNTs-Y) zeolites, the resulting CNCs-Y demonstrated superior performance in catalytic dealkylation with excellent activity and longevity, as well as the anti-coking ability thanks to the exceptional mesoporous features of CNCs-Y zeolites. Thereby the method and relevent CNCs-Y mesoporous zeolites based on the sustainable CNCs presented here have significant implications for being developed further for improving the sustainability of relevent catalytic processes such as fluid catalytic cracking (FCC).

A spinodal decomposition is often carried out in the austenite-ferrite duplex stainless steel Fe20Cr9Ni when it is serviced at 280-500℃ for a definite time, resulting in a decrease of pitting corrosion resistance. Fe-rich α phase rather than G phase has been suggested as the arch-criminal in causing the declining corrosion resistance of thermally-aged steel. Here, we found that ~76.8% of the decline in pitting resistance for the duplex stainless steel Fe20Cr9Ni was attributed to G phase, and ~23.2% to Fe-rich α phase after the spinodal decomposition. In this study, a suitable thermal aging treatment was introduced to obtain a larger size of the G-phase and to study the role of the phase in the corrosion process. Through immersing thermally-aged TEM specimen treated at 475℃ for 3000 h in NaCl solution, the preferential position of corrosion pits formed in the ferrite was obtained. The composition changes and strain field distribution around the G phase were analyzed by TEM-EDS, 3DAPT and GPA techniques. We further found that, although the concentration difference of Cr element between α and α' phases was as high as 60 at.%, corrosion pits were initiated at the interface between the G phase and the ferrite matrix rather than in the Fe-rich α phase, indicating that the Cr-depleted theory could not explain the aforesaid phenomenon. The strain energy at the interface between the G phase and the ferrite matrix was found to be the largest. The atoms at the interface have higher energy than in the intracrystalline, and thus easily react with Cl- ions in the solution to form pits finally.

Anisotropic mechanical behavior of nickel-based single crystal superalloy ( N B S C S ) is studied based on the displacement field near the crack tip during the fatigue crack growth at 980°C. A new distortion calibration technique for bi-prism-based single-lens 3D digital image correlation ( B S L 3 D D I C ) is proposed to in-situ and on-line characterize 3D full-field deformation with high precision. Virtual displacement extensometers ( V D E s ) are arranged from the displacement field for the crack opening displacement ( C O D ) determination. To the best of our knowledge, the effect of V D E s locations on the precision of C O D measurement is first theoretically analyzed, and the arrangement of V D E s has been optimized. Noticeably, similar quantitative analyses are conducted to determine crack opening ratio ( C O R ) for crack closure evaluation. Moreover, via fitting full-field displacement data to a theoretical model for anisotropic material, not only mode-Ⅰ effective stress intensity factor ( S I F ) expressed as K eff I and mode-Ⅱ effective S I F ( K eff Π ), but also theoretical S I F ( K theo I ), crack opening S I F ( K open I ) and crack opening load ratio ( C O L R ) are obtained. Based on these important fatigue parameters, modified Paris’ law is used to describe the high-temperature anisotropic crack growth behavior.

The corrosion behavior of lath bainitic and granular bainitic steels in 0.01 mol/L NaCl solution was studied by SEM and TEM observation, electrochemical monitoring and weight loss test. The results indicate that the micro galvanic couple forms between the steel matrix and the secondary phase, which causes non-uniform micro corrosion on surfaces of two steels. In lath bainitic steel, the secondary phase ω acts as the micro anode. While in granular bainitic steel, the secondary phase M acts as the micro cathode. Moreover, the corrosion acceleration caused by micro galvanic couple is obvious in the initial immersion stage, and then it becomes weak during the long term corrosion.

Microstructure evolution of a new cast Ni-base superalloy with various Ti contents is studied by thermodynamic calculations and experimental observations. According to thermodynamic calculations, when Ti content increases from 2.0 wt% to 4.0 wt%, the γ′ weight fraction firstly increases, and then tends to be relatively stable because of the precipitation of η phase. Two alloys containing 2.4 wt% and 3.0 wt% Ti are prepared to verify the accuracy of calculation results. After full heat treatment, γ′ phase, MC carbide and M23C6 carbide are precipitated from two alloys, but no η phase is detected. The quantity of γ′ phase and MC carbide in 3.0Ti alloy is higher than that in 2.4Ti alloy because Ti acts as one of their main forming elements. The higher amounts of γ′ phase and MC carbide obviously improve the mechanical properties of 3.0Ti alloy. To verify whether there is η phase in two alloys or not, long-term aging treatments are carried out at 700 °C, 750 °C and 800 °C for 3000 h. After long-term aging, needle-like η phase is precipitated from 3.0Ti alloy but not from 2.4Ti alloy. The quantity of η phase in 3.0Ti alloy gradually increases with the increase of aging temperature and time. Especially, the precipitation of η phase preferentially takes place beside grain boundaries and near MC carbides. The growth of η phase consumes γ′ phase and causes the appearance of γ′ depleted zones.

This work presents a simple method for the preparation of structured Co3O4 supported on silicalite-1/SiC foam catalyst (i.e., Co@S1/SiC), and its application to catalytic combustion of volatile organic compounds (VOCs, isopropanol as the model compound). The growth mechanism of Co3O4 on silicalite-1/SiC catalysts were systematically studied as a function of synthesis time based on comprehensive characterization using N2 adsorption-desorption analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectra (XPS). It was found that Co2SiO4 nano-sheets were formed within/on silicalite-1 coating at the initial stage of synthesis, which was further transformed into flower-like Co3O4 nano crystals on the surface of silicalite-1/SiC. The developed structured catalyst, especially the one prepared by the 40 h synthesis, i.e., Co@S1/SiC-40 h, combined high oxygen mobility, Co3+/Co2+ redox couple and improved adsorbed oxygen species, and exhibited excellent performance in complete thermocatalytic combustion of isopropanol.

Effects of plasma nitriding on oxidation behavior of 304 SS exposed in 290 °C high temperature and pressurized water have been investigated. The oxidation behavior of 304 SS with plasma nitriding was changed significantly after the exposure tests. Moreover, the nitriding time also had an obvious effect on the oxidation behavior. The difference in oxidation behavior was mainly due to the changes of pH value on the local area near the nitriding layer caused by the formation and hydrolysis of NH4+. The influencing mechanisms of the nitriding time on oxidation behavior in high temperature and pressurized water are also discussed.

It is important to fabricate iron-based nitride/conductive material composite to obtain good catalytic performance. In this work, Fe2N nanoparticles with diameter of approximately 30 nm have been successfully dispersed on the surface of nitrogen-doped graphite oxide (NrGO) by a facile sol–gel method and further ammonia atmosphere treatment. XPS, XRD, Raman, and TEM proved that Fe2N nanoparticles are well monodispersed, and nitrogen atoms are doped in NrGO. The composite possessed two merits, that is, the more catalytic active site in Fe2N nanoparticles due to the well monodispersion, and fast electron transfer due to the nitrogen dope in rGO. With the proper ratio, the composite exhibited brilliant catalytic activity and durability in acidic media. It possesses overpotential of 94 mV to approach 10 mA/cm2, a small Tefel slope of 49 mV/dec, and maintains the good electrocatalytic activity for 10 h. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that the electrocatalyst possessed high catalytic active area and fast electron transfer. Our work may provide a new avenue for the preparation of low-cost iron-based nitride/NrGO composite for highly efficient electrochemical hydrogen evolution.

MoN is a promising material for electrochemical hydrogen evolution due to its cheap price and excellent catalytic activity sites, but the low conductivity prevents further improvement of its catalytic performance. In this work, porous MoN nanorods have been fabricated with an efficient and facile precursor method. XRD, Raman and TEM showed MoN nanorods with diameters of about 100 nm. With a simple mechanical mixing method, MoN/conductive carbon black (CB) composites with different weight ratios have been fabricated. The composite possessed two merits, that is, the more catalytic active site in MoN nanorods due to the porous structure, and fast electron transfer due to the CB. So, it has been used as a hydrogen evolution material. With the proper weight ratio, the composite exhibited brilliant catalytic activity and durability in acidic media. It possesses an overpotential of 162 mV to approach 10 mA cm−2, a small Tefel slope of 54 mV dec−1 and maintains the good electrocatalytic activity for at least 10 h. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that the electrocatalyst possessed a high catalytic active area and fast electron transfer. These results can compare with many other recently reported nitride catalysts. Our work possibly provides a new avenue for the preparation of a MoN-based catalyst for highly efficient electrochemical hydrogen evolution.

Hematite (α-Fe2O3) is a red material with a band gap of about 2.0 eV, which indicates that it can absorb more solar light. It is a promising photocatalyst applied in many fields. In this paper, α-Fe2O3 single crystal hollow hexagonal bipyramids were synthesized by a simple one-pot hydrothermal method. The morphology and structure of the prepared α-Fe2O3 hollow hexagonal bipyramids were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The hollow single crystals show a good light absorption and performance in photodegradation of methylene blue (MB). Due to the strategy of depositing ultra-thin layers of Al2O3 by atomic layer deposition (ALD), the photoelectrochemical (PEC) performance of α-Fe2O3 under the simulated solar light irradiation is also improved.

Fully lamellar Ti-6Al-4V alloys comprise body-centered cubic (BCC) β lamellae in large-sized, hexagonal close-packed (HCP) α colonies and exhibit outstanding toughness. Although α/β interfaces are considered to play a key role in plastic deformation connected to the toughness, the interface effects have not been revealed so far. In this work, we studied underlying deformation mechanisms of interface-related deformation modes at an atomic scale. After the cyclic loading, {1‾102} deformation twins were observed in the vicinity of fatigue crack surfaces. Moreover, the α/β interface structures before and after cyclic loading deformation were characterized via transmission electron microscopy (TEM). The initial α/β interfaces can be described by the terrace ledge kink model, consisting of (01‾10)α||(‾121)β terrace plane and (‾1100)α||(‾101)β ledge plane. TEM investigations reveal that deformation twins nucleate at the α/β interface and the corresponding nucleation is ascribed to the dissociation of basal type dislocations. More importantly, these twins can continuously propagate through multiple β phase lamella. The continuous propagation of twinning is accomplished through double kinking mechanism. In this manner, twinning in α phases and sequential kinking in β phases can effectively release the stress intensification at the crack tip and dissipate plastic work/energy, correspondingly enhancing fracture toughness of fully lamellar Ti-6Al-4V.