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The thermal stability of Zr–Ti–Ni–Cu–Be and Pd–Ni–Cu–P multicomponent bulk metallic glasses (BMGs) has been evaluated by their Gibbs free energy of formation, ∆Ga. We found that the tight bonding solute-centred clusters (in which a solute atom is surrounded by many solvent atoms in the first coordination shell with strong solute-solvent interaction), and chemical short-range orders (chemical SRO) have a much more important effect on the thermal stability of multicomponent BMGs, than other clusters and short-range orders. The quasi-linear correlation between crystallization temperature, Tx, and ∆Ga is only valid for multicomponent BMGs with similar chemical SRO, in a narrow composition region. This study could be of importance in understanding the thermal stability and the underlying mechanism of crystallization of multicomponent BMGs.

This study determined that the homogenisation temperature range of experimental as-cast H13 steel was from 1150 to 1230 °C, whilst the effect of homogenisation temperature range on the microstructural evolution and microhardness was tested. The enrichment of alloying elements in the dendrite segregation region decreased the solidus temperature of matrix, whose total content determined the maximum homogenisation temperature. The secondary dendrite branches were most dissolved at 1150 °C, and overheating appeared at 1230 °C in the segregation region. Moreover, the primary carbides underwent shrinking, passivation, fragmentation and dissolution. The secondary carbides M23C6 and M6C were formed at the interfaces of MC/γ and M7C3/γ, respectively. As the homogenisation temperature increased from 1150 to 1230 °C, the value of microhardness gradually decreased from 771 to 740 HV. Nevertheless, the standard deviation value decreased first and then increased, which reached the minimum 32 HV at 1200 °C, indicating that the hardness homogeneity was the best.

The microstructure and properties of a Fe-2Cr-Mo-0.12C (wt pct)-tempered steel plate at different normalization temperatures after hot rolling were investigated to enhance its comprehensive mechanical properties. The microstructure of the steel was mainly composed of a ferrite-bainite-tempered martensite mixture after the normalization-tempering process. The tensile properties and the ductile-brittle transition temperature values indicated that the best comprehensive mechanical properties can be obtained by normalizing at 930 °C and tempering at 700 °C. When the normalization temperature was 880 °C to 930 °C, the yield strength increased as the bainite and tempered martensite hard phase volume fractions increased. However, when the normalization temperature surpassed 980 °C, the precipitation strength behavior compensated for the adverse influence of the effective grain size growth, and yield strength was nearly unchanged. Total elongation reached a peak value when normalized at 930 °C, due to the optimal volume fraction ratio of the soft to hard phase. The Charpy impact fracture changed from a ductile to a brittle fracture with an increase in the normalization temperature. When the normalization temperature was 930 °C, the existence of a certain volume fraction of nano-precipitates and soft ferrite in the microstructure contributed to excellent ductile properties.

The hot-working behavior of as-cast H13 hot work die steel was investigated in the method of isothermal compression test involving the wide deformation temperatures of 900–1150 °C and strain rates of 0.01–10 s−1, with the true strain to 0.8, on the MMS-200 thermo-mechanical simulator. Two characteristic parameters involving the critical strain for DRX initiation ( $$\varepsilon_{c}$$ ) and the strain for peak stress ( $$\varepsilon_{p}$$ ) were identified. The ratio of critical strain to peak strain ranged from 0.26 to 0.6, which decreased with the increase in temperature and decrease in strain rate. Processing maps were established using dynamic material model at strains of 0.2, 0.4, 0.6, 0.8. The power dissipation maps were not significantly affected by the strain, while the instability maps were sensitivity with the strain when it was over 0.4. The area of instability domain at strain of 0.8 was the largest. The instable characteristics contained the mixed grain structure, adiabatic shear band, intense deformation in serious deformation area and brittle elemental segregation area. The chief effect on the power dissipation was the strain rate, the optimum hot working parameters at strain of 0.8 (910–985 °C, 1010–1150 °C and 0.01–0.05 s−1) were determined. In this filed, the original coarse as-cast grains were gradually refined by dynamic recrystallization mechanism and the DRX grain numbers had a significant increase with the increase of power dissipation efficiency.

TiO2 nanospheres wrapped by graphene-like g-C3N4 nanosheets were fabricated through the one-pot solvothermal process and applied as lubricant additives in paraffin base oil to characterise the tribology performances. Moreover, g-C3N4/TiO2 composites were investigated by different characterisation methods such as X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, indicating the formation of g-C3N4/TiO2 composites. Subsequently, the friction experiment of the resulting samples using g-C3N4/TiO2 hybrids as additives in base oil were tested by a multispecimen friction and wear tester (UMT-2), which indicate g-C3N4/TiO2 composites possessed excellent tribological property including significantly reduced frictional coefficient and wear rate as an oil additive, owing to the presence of a thin physical lubricating film on the surface of the matrix.

Herein, we report a new castable nanostructured alloy (CNA), which was first melted in a vacuum induction furnace to introduce micron- and submicron-sized inclusions, strengthened by the multiscale secondary phases for fusion reactors. The large micron-scale inclusions are removed, whereas submicron-scale inclusions were retained during an electroslag remelting process. The ingot was subjected to heat treatment at 1050 °C for 0.5 h followed by heating at 650 °C for 1.5 h to obtain tempered martensite along with the nanosized (Ti, W) carbides. The improvement in the mechanical properties of the sample treated at 750 °C was attributed to the removal of blocky Y-rich inclusions along with the strengthening of the submicron-sized Y2O3 oxides. The performance of the sample treated at 650 °C was explained by the precipitation of the fine (Ti, W) carbides.

Microstructure and mechanical properties of the Fe-1.2Mn-0.3Cr-1.4Ni-0.4Mo-C tempered steel plate in three cooling processes (direct quenching, accelerated cooling + air cooling and air cooling) after hot rolling were investigated in this paper. The lath-martensite is obtained by direct quenching, whereas granular bainite, lath bainite, retained austenite and M/A constituents are observed in other two cooling processes. Meanwhile, the lath-martensite with higher cooling rate after hot-rolling could enhance the intensity of {332} texture, which is beneficial for the strength and toughness of the steel. After tempering at 680°C, the difference of yield strength is mainly caused by grain boundary strengthening and precipitation strengthening. The higher proportion of high misorientation boundary, stronger intensity of {332} texture, weaker intensity of {001} texture and fewer of M/A constituents (or retained austenite) will improve the impact toughness. All in all, the steel with optimum combination of strength and toughness is obtained by using direct quenching to room temperature after hot rolling.

The variation in plastic deformation of Fe-6.5 wt%Si alloy depends on antiphase domains and grain boundary character distribution. With the increase of rolling reductions from 50% to 85%, the increment of dislocation density causes decline of the sizes of antiphase domains, meanwhile the sharp and homogeneous distribution of γ-fiber texture is prone to obtaining a large fraction of CSL boundaries, thus the fracture deflection of 65% warm-rolled sheet is increased to 8.6 mm by 38.7% in comparison to that of 50% warm-rolled sheet (6.2 mm), and that of 85% warm-rolled sheet has nearly three times increment (18.2 mm).

The atomic-scale degree of B/B′ alternate cationic disorder is known to significantly influence the macroscopic properties of the quadruple perovskites AA3′B2B2′O12; however, the nature of this disorder has rarely been critically studied. Herein, the effect of B-site cationic arrangement on the electronic and magnetic properties of the quadruple perovskite CaCu3Fe2Nb2O12 was systemically investigated using the first-principles calculations. The results demonstrate that the B-site ordered CaCu3Fe2Nb2O12 is a ferrimagnetic insulator with antiferromagnetic coupling between the A′-site Cu and B-site Fe. The calculated total magnetic moment is 7.00 μB f.u.−1, which is apparently larger than the experimentally measured saturation magnetization because of different degrees of the B-site disorder. Furthermore, the electronic structures illustrate that the magnetic moments sharply decrease with an increase in the B-site antisite defects, i.e., the total magnetic moments obviously reduce with an increase in the B-site Fe/Nb disorder, and ultimately, no magnetism is observed. Interestingly, the B-site antisite defects not only introduce Fe–Fe antiferromagnetic coupling, but also induce the antiferromagnetic arrangement of Cu spins in the totally disordered structure. Cu–Fe and Fe–Fe magnetic coupling competition is coupled with antisite defects, and finally, Fe–Fe antiferromagnetic coupling turns into the dominating spin coupling in the disordered CaCu3Fe2Nb2O12. Moreover, the B-site antisite defects do not alter the insulator nature of the perovskite despite the significantly narrowed band gap. Our study opens up a novel avenue for the straightforward understanding of the effect of cationic ordering on the electronic and magnetic properties of quadruple perovskites and offers an additional opportunity for tailoring their characteristics.

A systematic investigation on grain growth behavior, grain boundary character distribution and mechanical properties of Fe-21Cr-15Ni-6Mn-Nb non-magnetic stainless steel was performed after solution treatment in temperature range of 1100–1200 °C with various durations. The results showed the hot-rolled plate still maintained fine microstructure with the grain size range of 11.5–19.6 µm after solution treatment. A Nb(C, N) drag mechanism concurrent with a restraining effect of Σ3n boundaries during solution treatment resulted in a slow kinetics with grain growth exponent n of ~ 4. The proliferation mechanism of Σ3n boundaries mainly varied from Σ3 regeneration to new twinning accompanied by grain growth. Twin boundary has an effective strengthening role like a grain boundary. The YS, UTS and elongation of solution-treated plate was above 634.0 MPa, 838.9 MPa, 45.3％, respectively, which were superior to the conventional austenitic stainless steel. The Hall-Petch relationship was determined well between the grain size under the condition of either including or excluding twin boundaries and tensile results. An inherent relationship between k ′ and k ( k ′ and k correspond to the circumstance of including and excluding twin boundaries, respectively), was expressed by k ′ = 1.52037 + 1.67168 k .

In-situ tensile test accompanied by electron backscatter diffraction (EBSD) analyses were performed on polygonal ferrite (PF) and bainite dual-phase steel, selected regions of interest were analyzed following plastic deformation of the steel. Deformation-induced crystal orientation evolution, localized strain concentration, slip transfer, and geometrically necessary dislocation (GND) density were tracked. Results revealed that heterogeneity deformation facilitated formation subregions with crystal orientation deviation in grain and fragmented the grain by the new low angle grain boundaries (LAGBs) or medium angle grain boundaries (MAGBs). The PF grains with ND// preferred crystal orientation exhibited high orientation stability, and almost all load axes of the selected PF grains moved to the [101] pole, resulting in enhancing {111} orientation component at high strain levels. With the lattice rotation during deformation, the high angle grain boundaries (HAGBs) can change to MAGBs, which was beneficial to maintain coordination deformation among grains. Localized strain concentration can be decreased by the slip transfer across the PF grain boundaries or bainite/PF phase boundaries, which reduced the risk of micro-void formation. Additionally, the variation of α12 GND tensor average value (Ave. α12) revealed that the ferrite was continuous plastic deformation, while the bainite occurred stage hardening. The required strain for the coordination deformation was controlled by strain hardening behavior.

This study investigates the inclusions, microstructure, tensile properties, and impact toughness of reduced activation ferritic/martensitic (RAFM) steels with different Y contents (0.006, 0.034 and 0.071 wt-%). Owing to the pinning of the grain boundary to the Y inclusions (which refines the original austenite grain size) and an existing Fe–Cr–Ta–Y–S–O phase, the tensile strength at both room and high temperatures increased with increasing Y content (below 0.071%). Increasing the Y content to 0.034 wt-% decreased the ductile-to-brittle transition temperature (DBTT). However, when the Y content reached 0.071 wt-%, the DBTT increased as the Y precipitated into blocky yttrium-rich inclusions. The microstructure, tensile properties, and impact toughness of the RAFM steel were optimised at a Y content of approximately 0.034 wt-%.

Effect of initial pearlite morphology on the microstructure evolution during spheroidization annealing and subsequent hardening treatment was studied in hot-rolled 1.0C–1.5Cr bearing steel. The ferrite-to-austenite transformation in spheroidization annealing can be accelerated by refining the pearlite interlamellar spacing and pearlite colony size. Decreasing interlamellar spacing is also beneficial to increasing the number density of undissolved cementite, leading to the refining of final spheroidized cementite. During the re-austenitizing process of hardening treatment, the smaller initial spheroidized cementite leads to faster cementite dissolution and finer undissolved cementite particles. The prior austenite grain size after hardening treatment can also be decreased by refining the initial pearlite microstructure.

This paper presents a study on the three-dimensional characterization and modeling of morphology of diamond abrasive grains and electroplated diamond grinding wheels. A diamond abrasive grain was modeled by a cubo-octahedron that was determined by the intersection between an octahedron and a cube. The study revealed that the side length of octahedron and its side-length ratio followed a normal distribution and a generalized extreme value distribution, respectively. High-precision characterizations of grain density and protrusion height were realized by measuring wheel replicas with laser scanning confocal microscopy (LSCM). It was found that the grain protrusion height followed a normal distribution with an average of ∼40% of the grain size. Considering the randomly-distributed shape, size, position and protrusion height of abrasive grains, a geometric model of electroplated diamond wheels was established. The results show that the predicted morphology of grinding wheels agreed well with the experimentally measured. The model enables an accurate kinematic simulation for designing precision grinding processes.

The evolution of microstructure and texture of Fe-19Cr-2Mo-Nb-Ti ferritic stainless steel annealed at different temperatures was investigated using a combination of X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). EBSD investigations confirm that the in-grain shear bands provide more recrystallization nucleation sites to γ-fiber recrystallization grains with high Taylor factor orientations during cold rolling requiring further annealing for a more homogenous equiaxied grain structure. As the annealing temperatures increase, the grains in center layer are oriented towards {110}∥ND, and the recrystallization grains at 1050 °C are dominated by the uniform and equiaxial γ-fiber grains favourable for the improvement of r-values, while the occurrence of {100} 〈011〉 texture detrimental to r-values indicates that an exorbitant annealing temperature can reduce the intensity of γ-fiber textures affecting the formability, accordingly, the average plastic strain ratio of ferritic stainless steel increases sharply up to a maximum value (1.69) and then decreases to a certain value (1.42).

In this work, a facile and efficient method to overcome the poor dispersion of carbon nanotubes (CNTs) in the polymer matrix by in-situ synthetizing ZnS nanoparticles onto their surfaces was developed. The as-prepared CNTs/ZnS hybrid was then used as lubricating additive to enhance the friction-reducing and anti-wear properties of epoxy (EP) coatings. The microstructure and composition of CNTs/ZnS were characterized using HRTEM, FESEM, XRD, and RS. The ZnS nanoparticles with the size of about 20–30 nm were coated onto CNTs surface homogeneously in the form of wurtzite structure phase. Besides, the enhancement mechanisms of CNTs/ZnS on the tribological properties of EP coating were studied systematically. The results revealed that as the content of CNTs/ZnS was 1.25 wt%, the corresponding coatings possessed the lowest friction coefficient and highest wear resistance. Moreover, the EP coatings with the different weight fraction of CNTs/ZnS hybrid showed much better tribological properties than those with CNTs or acid-CNTs. The excellent tribological properties were mainly related to good dispersion of CNTs or ZnS as well as good synergism between CNTs and ZnS.

Hot deformation behaviour of Fe–21Cr–15Ni–Nb–V stainless steel was investigated by isothermal compression in the temperature range of 950–1150°C with a strain rate of 0.01–10 s−1. The results showed that complete recrystallisation occurred beyond 1050°C, resulting from the pinning effect of (Nb, V)(C, N). The nucleation of dynamic recrystallisation (DRX) was performed by the bulging, sub-grain swallowing and twinning mechanism. With increasing strain rate, new twinning was transformed into the Σ3 regeneration mechanism in the partial DRX region, while an opposite transformation was observed in the complete DRX region. In the partial recrystallisation region, grain rotation resulted in the formation of 110 orientation. In the complete recrystallisation region, the texture tended to distribute randomly at a high strain rate, and the grain growth was accompanied by the emergence of stable 100 orientation.

Using thermo-mechanical control process, the online spheroidization annealing process of 1.0C-1.5Cr bearing steel was designed. Apart from intercritical online spheroidization (IS), a novel subcritical online spheroidization (SS) process was proposed, which is characterized by water-cooling to around 773 K (500 °C) after the final rolling pass, and then directly reheating to 973 K (700 °C) for isothermal holding. Compared with the results from the traditional offline spheroidization (TS) process, the size of spheroidized carbides is similar in both the TS and IS processes, whereas it is much smaller in the SS process. After spheroidization annealing, microstructure evolution during austenitization and quenching treatment was examined. It is shown that the refining of spheroidized carbides accelerates the dissolution of carbides during the austenitizing process, and decreases the size of undissolved carbides. In addition, the SS process can obtain finer prior austenite grain after quenching, which contributes to the enhancement of final hardness.

In this study, influences of molybdenum on acicular ferrite formation on precipitated TiC particles are investigated from thermodynamic and kinetic respects. In thermodynamics, Segregation of Mo towards austenite/TiC interface releases the interfacial energy and induces phase transformation from austenite to acicular ferrite on the precipitated TiC particles. The Phase transformation can be achieved by displacive deformation along uniaxial Bain path. In addition, the segregation of Mo atom will also lead to the enhanced stability of ferrite in comparison with austenite no matter at low temperature or at high temperature. In kinetics, the Mo solute in acicular ferrite can effectively suppress the diffusion of carbon atoms, which ensures that orientation relationship between acicular ferrite and austenitized matrix can be satisfied during the diffusionless phase transformation. In contrast to ineffectiveness of TiC particles, the alloying Mo element can facilitate the formation of acicular ferrite on precipitated TiC particles, which is attributed to the above thermodynamic and kinetic reasons. Furthermore, Interfacial toughness and ductility of as-formed acicular ferrite/TiC interface can be improved simultaneously by segregation of Mo atom.

This paper characterises the high thermal conductivity thin-film substrate systems and the interface thermal resistances between the films. First, three-omega (3ω) method was proposed and verified, obtaining a reliable thermal conductivity measurement at shallow thermal-penetration depths. The method was then applied to a thin-film/substrate system to identify the individual thermal conductivities. The interface thermal resistance between the thin films was then successfully characterised with the aid of theoretical modelling and experimental measurements. As an example of the method application in the IC industry, the AlN/Si systems were investigated. The study identified that the thermal conductivity of the 2 μm-thick AlN film in an AlN/Si system is 172.1 W/mK and the AlN/Si interface thermal resistance is 1.796 × 10− 9 m2 K/W.

Thermal simulated specimens with the heat inputs of 20, 50 and 80 kJ/cm were used to investigate the effects of heat input on the microstructure and mechanical properties of the Fe–2Cr–Mo–0.12C pre...

The combined effect of B2 phase transfer and grain boundary character on mechanical properties of the Fe-6.5 wt% Si alloy was investigated. The microstructures and textures of the Fe-6.5 wt% Si alloy under four cooling modes were characterized by X-ray diffraction, transmission electron microscope, and electron backscattered diffraction. The results reveal that the maximum nano-hardness value (8.9 GPa) results from the two-step air-cooling sample, while for the two-step water-cooling sample, the minimum value (5.3 GPa) is achieved. The transformation of the B2 phase affected by the water-cooling process is a critical factor in obtaining the lower APB energy and eliminating the brittlenes. A large fraction of the coincidence site lattice boundaries that formed on the sheet experienced the two-step water-cooling process due to a uniform and sharp γ-fiber recrystallization texture comprising the {111} 〈110〉 and {111} 〈112〉 components, which enhances resistance to intercrystalline effect and improves mechanical properties in comparison with the two-step air-cooling process.

In this paper, the Maxwell–Wagner effect and the charge characteristics of the heterogeneous interface at the action of higher electric field and elevated temperature are investigated by means of electret technology. A composite membrane with a double-layer structure of a polypropylene (PP) film and a fluorinated ethylene propylene copolymer (FEP) film was made. After being polarized under electric field and elevated temperature, the component PP and FEP films of the composite membranes were separated. The charge density of the PP and FEP films was measured to analyze the characteristics of interfacial charge in the composite membrane. Experimental results directly prove that the charge characteristics at the interface of the composite membranes are consistent with the result calculated by the Maxwell–Wagner effect. The polarity of the interfacial charge can be switched by changing the polarity of the polarizing voltage. The characteristics of the accumulated interfacial charge are strongly dependent on the conductivity, which is affected by the temperature and the polarizing electric field. A new phenomenon, that is, the measured charge density is much higher than that calculated by the Maxwell–Wagner effect, is found. The reason is ascribed to the electret effect from the FEP and PP films. This research provides a new insight into the charge characteristics at the heterogeneous interface.

A nanoplate-like Bi-based heterojunction was firstly prepared through in situ formation of Bi2S3 nanocrystals on the surface of BiOBr nanoplates via a facile anion exchange strategy. The as-prepared Bi2S3/BiOBr heterojunctions were carefully characterized by multiple physicochemical techniques. The photocatalytic activity of as-synthesized samples were evaluated by the photodegradation of ciprofloxacin (CIP) under visible-light irradiation (λ > 420 nm). Compared to the pristine BiOBr, the Bi-based heterojunctions exhibited dramatically enhanced photocatalytic activity towards the CIP degradation in aqueous solution. Moreover, it is found that the 4% Bi2S3 coupled BiOBr heterojunction showed the superior photoreactivity for removal of CIP, which is about 2.8-folds higher than that of pure BiOBr. The significantly improved photoactivity was ascribed to the effective separation of photogenerated electron-hole pair’s between the Bi2S3 and BiOBr. This work highlights a simple approach to design the Bi-based nanocomposites and develops an efficient visible-light-driven heterojunction material for application in antibiotic pollutant purification.

Advanced reduced graphene oxide/ZnS (RGO/ZnS) hybrids were synthesized via a facile and effective hydrothermal method to enhance the tribological properties of epoxy coatings. Physical characterization of the hybrids indicated that the as-prepared products had the high chemical purity and that the ZnS nanoparticles combined well with RGO nanosheets. Meanwhile, ZnS nanoparticles were uniformly dispersed on RGO nanosheets with the diameters of several decade nanometers. The tribological properties of ZnS, RGO, and RGO/ZnS with epoxy coating were systematically investigated. By comparing the result of tribological study, it was found that RGO/ZnS hybrids had better lubricating properties with lower coefficient of friction and higher wear resistance than those of ZnS or RGO. In addition, the test results indicated that RGO/ZnS hybrids showed good stability with increased in applied load. These excellent tribological properties of RGO/ZnS hybrids were attributed to the excellent synergistic effects between ZnS nanoparticles and RGO nanosheets and to the transfer film that formed on the steel ball. This work paved a way to expand the potential applications of nanoparticles in the tribological field.

The predictability of modified constitutive model, based on Arrhenius type equation, for illustrating the flow behavior of Fe-36%Ni Invar alloy was investigated via isothermal hot compression tests. The hot deformation tests were carried out in a temperature range of 850–1100 °C and strain rates from 0.01 to 10 s−1. True stress-true strain curves exhibited the dependence of the flow stress on deformation temperatures and strain rates, which then described in Arrhenius-type equation by Zener-Holloman parameter. Moreover, the related material constants and hot deformation activation energy (Q) in the constitutive model were calculated by considering the effect of strain as independent function on them and employing sixth polynomial fitting. Subsequently, the performance of the modified constitutive equation was verified by correlation coefficient and average absolute relative error which were estimated in accordance with experimental and predicted data. The results showed that the modified constitutive equation possess reliable and stable ability to predict the hot flow behavior of studied material under different deformation conditions. Meanwhile, Zener-Holloman parameter map was established according to the modified constitutive equation and used to estimate the extent of dynamic recrystallization.

A series of K 3 B 6 O 10 Br (KBB) polar crystals have been grown along , and seed directions by top seeded solution growth (TSSG) method. By optimizing the growth condition, transparent KBB crystal with the sizes of 52×29×25 mm 3 was successfully grown by using seed -orientation from KF–PbO flux. The full-width at half-maximum (FWHM) and optical homogeneity were measured as 0.0038° and 3.3×10 −5 from the rocking curve and optical interferometry measurements, respectively, indicating high optical quality of the as-grown crystals. The Verdet coefficient of KBB crystal was obtained as 5.3 rad T −1 m −1 at 635 nm by comparative method.

Visible-light-driven core–shell structured AgBr/g-C3N4 heterogeneous photocatalyst have been synthesised by a sonication-assisted deposition-precipitation route at room temperature, and characterised by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscope, UV–visible diffuse reflectance spectroscopy and N2 adsorption–desorption analysis. Subsequently, the photocatalytic activity of AgBr/g-C3N4 is evaluated by the degradation of typical Rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under visible-light irradiation (>420 nm). The as-prepared AgBr/g-C3N4 core–shell photocatalyst show higher photocatalytic activity than the pure g-C3N4 and AgBr nanoparticles, which is ascribed to synergistic effects at the interface of AgBr and g-C3N4 . Moreover, superior stability was also observed by recycling experiments indicating that core–shell structured AgBr/g-C3N4 was highly desirable for the remediation of organic contaminated wa...

Fe–6.5 wt%Si electrical steel characterized with excellent soft magnetic properties such as almost zero magnetostriction, low eddy current and hysteresis losses characteristics has been widely applied in high frequency fields. In this work, the role of texture evolution and ordered phase transition in soft magnetic properties of annealed sheets was explored using EBSD, XRD and TEM. The results demonstrate that accompanied with the increase of annealing temperatures, an increase on the B8 is attributable to a contribution combining the sizes of recrystallization grains with APBs of ordered phases as pinning the migration of magnetic domain wall. Whereas B50 declines to a minimum value (1.479 T) and then increases to a certain value (1.695 T) due to different types and intensities of textures affecting on the magnetocrystalline anisotropy energy. Meanwhile, the dislocation density gradually decreases and corresponding to a gradual decline in the internal stress, which makes the coercive force (H c ) decrease monotonically.

In this paper, the microstructural evolution and deformation mechanism of the cryorolled Fe–36%Ni alloy was investigated. Deformation twinning was confirmed to be activated at the early stage of cryorolling (CR) and subsequently suppressed due to microstructure refinement. The existence of and peaks revealed that the (α′-M) phase transformation was induced during the CR process. The stress-assisted martensite and strain-induced martensite were detected to be transformed at the grain boundary and intersection of deformation twins, respectively. Owing to the co-effect of the temperature raise and mechanical stabilisation, the α′-M phase transformation was suppressed during the CR process. Therefore, the amount of the α′-M was limited in the tested alloy.

Structural and electronic properties of 3d transition metal Sc, Ti, Cr and Mn incorporated 2 H -WSe 2 have been systematically investigated by first-principles calculations based on density functional theory. The calculated formation energies reveal that all the doped systems are thermodynamically more favorable under Se-rich condition than W-rich condition. The geometry structures almost hold that of the pristine 2 H -WSe 2 albeit with slight lattice distortion. More importantly, the electronic properties have been significantly tuned by the dopants, i.e., metal and semimetal behavior has been found in Sc, Ti and Mn-doped 2 H -WSe 2 , respectively, semiconducting nature with narrowed band gap is expected in Cr-doped case, just as that of the pristine 2 H -WSe 2 . In particular, magnetic character is realized by incorporation of Mn impurity with a total magnetic moment of 0.96 μ B . Our results suggest chemical doping is an effective way to precisely tailor the electronic structure of layered transition metal dichalcogenide 2 H -WSe 2 for target technological applications.

The photocatalytic water splitting for generation of clean hydrogen energy has received increasingly attention in the field of photocatalysis. In this study, the Ta2O5/g-C3N4 heterojunctions were successfully fabricated via a simple one-step heating strategy. The photocatalytic activity of as-prepared photocatalysts were evaluated by water splitting for hydrogen evolution under visible-light irradiation (λ > 420 nm). Compared to the pristine g-C3N4, the obtained heterojunctions exhibited remarkably improved hydrogen production performance. It was found that the 7.5%TO/CN heterojunction presented the best photocatalytic hydrogen evolution efficiency, which was about 4.2 times higher than that of pure g-C3N4. Moreover, the 7.5%TO/CN sample also displayed excellent photochemical stability even after 20 h photocatalytic test. By further experimental study, the enhanced photocatalytic activity is mainly attributed to the significantly improve the interfacial charge separation in the heterojunction between g-C3N4 and Ta2O5. This work provides a facile approach to design g-C3N4-based photocatalyst and develops an efficient visible-light-driven heterojunction for application in solar energy conversion.

Direct γ→α′ martensitic transformation during cold rolling deformation was investigated for a high-Mn non-magnetic steel. Its influence on magnetic property was also analyzed. The magnetization under rolling reduction less than 50% almost presents a linear increase with the applied magnetic field. With deformation up to 73% and 93% thickness reductions, strain induced α′-martensite transformation starts to occur, causing the steel to be slightly magnetized. The α′-martensite prefers to nucleate directly at either microband–microband or microband-twin intersections without participation of intermediate e-martensite. The volume fraction of α′-martensite is estimated as 0.070% and 0.17%, respectively, based on the magnetic hysteresis loops. Such a small fraction of ferromagnetic α′-martensite shows little influence on the magnetic induction intensity and low relative permeability.

Effect of initial martensite and tempered carbide characteristics on mechanical properties of 3Cr2MnNiMo mold steel were investigated. The results indicated that the initial martensite microstructure can be effectively adjusted by changing the quenching temperature. With the increase of quenching temperature from 760 °C to 1010 °C, the initial microstructure gradually changed from acicular ferrite + plate martensite + M7C3 carbides to lath martensite, and the grain size increased monotonically. The coarsening of the initial martensite led to the increase of tempered carbide size, and the morphology of tempered carbide gradually changed from spherical to long strip-shaped. The large-size and long strip-shaped carbides promoted the formation of micro-voids during the tensile deformation and significantly decreased the elongation. In addition, with the coarsening of the martensite microstructure, both the decrease of high-angle grain boundaries (HAGB) density and the appearance of long strip-shaped tempered carbides significantly reduced the impact absorbed energy. The fracture mechanism transformed from ductile fracture caused by micro-voids coalescence to intergranular cleavage fracture. Moreover, when the initial microstructure completely transformed into lath martensite, the yield and tensile strength remained approximately unchanged. The precipitation strengthening compensated the adverse effect of martensite coarsening.

Micro-textures and mechanical properties of Fe–21Cr–15Ni–6Mn–Mo–Nb austenitic stainless steel during asymmetric hot rolling were studied. The results show that the shear texture is the dominant texture on the upper surface of steel sheet when the specific velocity ratio is 1.1, and the orientation of γ-Fiber was beneficial to recrystallization and nucleation. The texture strength of the central layer of the steel plate was concentrated in the Cube orientation. When the velocity ratio increases to 1.2, the complete recrystallization of the upper and central layers of the plate was more likely to occur under the condition of high deformation energy, and the structure of the steel sheet had tended to homogenize. Under the conditions of low reduction (20%) or low finishing temperature (860 °C), the steel sheet was partially recrystallized or non-recrystallized, and there were a lot of deformation textures during rolling. In the process of asymmetric hot rolling, the crystal rotates around the direction of TD, and the initial texture of weak γ-Fiber and Copper deviates from the ideal position and gradually approaches to the direction of γ-Fiber. Based on the research, the tested austenitic stainless steel had high strength and toughness (the yield strength, the tensile strength and the elongation is 710.1 MPa, 1010.2 MPa and 46.7%) under the rolling process with specific speed ratio 1.2, the initial rolling temperature 1100 °C and the reduction 60%.

In this paper, we discussed a method for the measurement and characterization of a three-step height sample using a stylus profiler. The original measurement data were processed by a polynomial fitting based algorithm to reduce low frequency artefacts. A low pass filter with the cutoff frequency of 0.8/μm was used to remove the high frequency noise, and a ten order polynomial was used to effectively remove the low frequency artefacts. The experimental results indicated that the uncertainties of the step heights were between 1 nm and 2.2 nm. Furthermore, the deposition rate of the step films with uncertainty was calculated as an application of the sample measurement. The results indicate that the deposition rate for the step films based on the measurement of the stylus profiler was consistent with that of a spectroscopic ellipsometer.

Graphite-like bulk NbTe2 powders were prepared by a facile solid phase synthesis process and ultrathin NbTe2 nanosheets were obtained by using wet ball milling induced delamination. The X-ray diffraction analysis illustrated that the reduction of particle size was mainly along the stacking direction of the basal planes without great influence on the short range order of NbTe2 crystals. Scanning electron microscopy, transmission electron microscopy, and atomic force microscope observations revealed that the longitudinal dimension of NbTe2 samples changed into the nanoscale from the larger micron level after mechanical exfoliation. The exfoliated NbTe2 nanosheets had better long-term dispersion stability in paraffin oil than bulk NbTe2. The tribological properties were determined on an UMT-2 ball-on-disk friction and wear tester. The results indicated that the paraffin oil with NbTe2 nanosheets exhibited better lubricating behaviors with the lower friction coefficient and wear rate in comparison with the bulk NbTe2. It was demonstrated that NbTe2 nanosheets could easily enter into a point of friction contact, and form an available tribofilm to prevent the direct contact between counterparts during the friction process. Furthermore, this work shows the potential applications of ultrathin NbTe2 nanosheets in the field of tribology.

Ordered phases and ductility of Fe–6.5 wt% Si magnetic material were investigated under different rolling temperatures, and the constitutive equation of the warm deformation was established. The results show that at high rolling temperature, accompanying with the appearance of some shallow dimples, the intergranular fracture can be transformed into the quasicleavage fracture, which makes the ductility of warm-rolled sheets greatly improved. In the 450–650 °C rolling temperature range, the antiphase domains (APDs) of warm-rolled sheets are cut, the superdislocation density increases greatly with decreasing warm rolling temperatures, resulting in a decrease in APD sizes during warm deformation. Meanwhile, more B2 and DO3 ordered phases occurring in the matrix improve the long range order parameters, thereby significantly reducing ductility of the alloy. The work softening of Fe–6.5 wt% Si alloy is attributed to a contribution combining the sizes of APDs with ordered phases.

The spheroidized 1.0C–1.5Cr bearing steel with 30% cold deformation in thickness was subjected to austenitizing treatment. Interrupted quenching was employed to study the effect of prior cold deformation on the microstructure evolution during austenitizing. The results indicate that, due to the formation of many low angle boundaries, the prior cold deformation facilitates the initial dissolution of cementite during the austenitizing and decreases the final prior austenite grain size. With the dissolution of cementite, mean diameter of cementite particles decreases first and then increases. When the volume fraction of undissolved cementite was within 3.7–4.9%, the mean diameter of cementite particles would have the smallest value of approximately 0.21 µm. After tempering at 170 °C for 2 h, the impact toughness and hardness of the experimental steels with the austenitizing temperature of 850 °C were measured. The prior cold deformation increases the impact absorbed energy by approximately 7%. The fracture surface exhibits quasi-cleavage fracture. At the austenitizing time of 30 min and 60 min, nearly no fibrous region can be observed, and fracture occurs by the nucleation of microcracks at the interfaces of martensite-cementite.

The pitch measurement and AFM calibration precision are significantly influenced by the grating pitch evaluation method. This paper presents the ensemble empirical mode decomposition (EEMD) based pitch evaluation method to relieve the accuracy deterioration caused by high and low frequency components of scanning profile during pitch evaluation. The simulation analysis shows that the application of EEMD can improve the pitch accuracy of the FFT-FT algorithm. The pitch error is small when the iteration number of the FFT-FT algorithms was 8. The AFM measurement of the 500 nm-pitch one-dimensional grating shows that the EEMD based pitch evaluation method could improve the pitch precision, especially the grating line position precision, and greatly expand the applicability of the gravity center algorithm when particles and impression marks were distributed on the sample surface. The measurement indicates that the nonlinearity was stable, and the nonlinearity of x axis and forward scanning was much smaller than their counterpart. Finally, a detailed pitch measurement uncertainty evaluation model suitable for commercial AFMs was demonstrated and a pitch uncertainty in the sub-nanometer range was achieved. The pitch uncertainty was reduced about 10% by EEMD.

In this paper, we report a facile and versatile modified hydrothermal method for synthesis of three-dimensional (3D) hierarchical flower-like MoSe 2 microspheres using selenium powders and sodium molybdate as raw materials. The as-prepared MoSe 2 was investigated for application as an adsorbent for the removal of dye contaminants from water. Power X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS) and N 2 adsorption-desorption analysis were carried out to study the microstructure of the as-synthesized product. A possible growth mechanism of MoSe 2 flower-like microspheres was preliminarily proposed on the basis of observation of a time-dependent morphology evolution process. Moreover, the MoSe 2 sample exhibited good adsorption properties, with maximum adsorption capacity of 36.91 mg/g for methyl orange. The adsorption process of methyl orange on 3D hierarchical flower-like MoSe 2 microspheres was systematically investigated, which was found to obey the pseudo-second-order rate equation and Langmuir adsorption model.

Through-thickness microstructure gradient as a function of asymmetric hot rolling (ASHR) process parameters was investigated for a high manganese non-magnetic steel. Shear strain distribution was calculated using a two-dimensional finite element method. According to the simulation results, the surface layer of ASHR plate undergoes the highest total shear deformation which leads to the formation of a fine-grained surface layer under conditions of large rolling reduction and relatively high temperature. In the central layer is still the partially recrystallized microstructure. With velocity ratio increasing, the depth of fine-grained surface layer approaches 1/4 plate thickness, while the recrystallization proportion for the central layer is also enhanced due to the reinforced extra shear deformation. By appropriate parameter optimization, the austenitic grain size is finally refined to ~5 µm for the surface layer and ~9 µm for the center, such that the tensile property is improved.

In this paper, the microstructure and mechanical properties of Fe-36%Ni alloy after 90% reduction of cryorolling (CR) and subsequent annealing were investigated. The X-Ray diffraction (XRD) results indicated the existence of γ → α , phase transformation, and the measurement result of the α , volume fraction was 15%. Lath α , with average thickness of 29.3 nm was then observed by transmission electron microscope (TEM). After 90% reduction of CR, the ultimate strength (UTS) of the tested alloy was enhanced to 1100 MPa. This was mainly due to high density defects formation and α , transformation during CR. After annealing at 823 K for 5 min, TEM results revealed that a multimodal grain structure was produced, the UTS of the tested alloy was decreased to 830 MPa, total elongation (EL) was increased to 8%. With the increasing of annealing time, the recrystallized grains were gradually coarsened and the volume fraction was increased. The increase of ductility was accompanied by the significantly decrease of strength. The cryorolled Fe-36%Ni alloy was fully recrystallized after annealing at 823 K for 30 min. The grain size distribution indicated that nearly 62% of the grains were less than 3 µm and there were a few large grains more than 10 µm. The recrystallized sample exhibited a good mechanical property with a higher tensile strength of 550 MPa and total EL of 36%, which was probably due to the bimodal microstructure.