Microstructures and micromechanical behaviors of high -entropy alloys investigated by synchrotron X-ray and neutron diffraction techniques: A review

High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Extensive studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural materials.Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials.Recently,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation processes.In this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are discussed.The factors that influence the deformation mechanisms of HEAs are also outlined.This review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress changes.Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.

Interfacial Modification of NiO_(x)by Self-assembled Monolayer for Efficient and Stable Inverted Perovskite Solar Cells

NiO_(x)as a hole transport material for inverted perovskite solar cells has received great attention owing to its high transparency,low fabrication temperature,and superior stability.However,the mismatched energy levels and possible redox reactions at the NiO_(x)/perovskite interface severely limit the performance of NiO_(x) based inverted perovskite solar cells.Herein,we introduce a p-type self-assembled monolayer between NiO_(x)and perovskite layers to modify the interface and block the undesirable redox reaction between perovskite and NiO_(x)The selfassembled monolayer molecules all contain phosphoric acid function groups,which can be anchored onto the NiOr surface and passivate the surface defect.Moreover,the introduction of self-assembled monolayers can regulate the energy level structure of NiO_(x),reduce the interfacial band energy offset,and hence promote the hole transport from perovskite to NiO_(x)layer.Consequently,the device performance is significantly enhanced in terms of both power conversion efficiency and stability.

Advances in Liquid Crystal Epoxy:Molecular Structures,Thermal Conductivity,and Promising Applications in Thermal Management

Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large-power,high-frequency,and highvoltage insulating packaging applications,due to the challenge of achieving high thermal conductivity(k),desirable dielectric performance,and robust thermomechanical properties simultaneously.Liquid crystal epoxy(LCE)emerges as a unique epoxy,exhibiting inherently high k achieved through the self-assembly of mesogenic units into ordered structures.This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy,while demonstrating a prominently enhanced k.As such,liquid crystal epoxy materials represent a promising solution for thermal management,with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment.This article provides a comprehensive review on recent advances in liquid crystal epoxy,emphasizing the correlation between liquid crystal epoxy’s microscopic arrangement,organized mesoscopic domain,k,and relevant physical properties.The impacts of LC units and curing agents on the development of ordered structure are discussed,alongside the consequent effects on the k,dielectric,thermal,and other properties.External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated.Finally,potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed.

Dimethyl acridine-based self-assembled monolayer as a hole transport layer for highly efficient inverted perovskite solar cells

Self-assembled monolayers(SAMs)have recently emerged as excellent hole transport materials in inverted perovskite solar cells(PSCs)owing to their ability to minimize parasitic absorption,regulate energy level alignment,and passivate perovskite defects.Herein,we design and synthesize a novel dimethyl acridinebased SAM,[2-(9,10-dihydro-9,9-dimethylacridine-10-yl)ethyl]phosphonic acid(2PADmA),and employ it as a hole-transporting layer in inverted PSCs.Experimental results show that the 2PADmA SAM can modulate perovskite crystallization,facilitate carrier transport,passivate perovskite defects,and reduce nonradiative recombination.Consequently,the 2PADmA-based device achieves an enhanced power conversion efficiency(PCE)of 24.01%and an improved fill factor(FF)of 83.92%compared to the commonly reported[2-(9H-carbazol-9-yl)ethyl]phosphonic acid(2PACz)-based control device with a PCE of 22.32%and FF of 78.42%,while both devices exhibit comparable open-circuit voltage and short-circuit current density.In addition,2PADmA-based devices exhibit outstanding dark storage and thermal stabilities,retaining approximately~98%and 87%of their initial PCEs after 1080 h of dark storage and 400 h of heating at 85°C,respectively,both considerably superior to the control device.

Comparison of Anterior Segment Optical Coherence Tomography and Ultrasound Biomicroscopy for Iris Parameter Measurements in Patients with Primary Angle Closure Glaucoma

Purpose: To compare the repeatability and consistency of anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in measuring iris parameters in patients with primary angle closure glaucoma. Methods: Twenty-two patients (38 eyes) with primary angle closure glaucoma,including 5 eyes with acute angle closure glaucoma,10 fellow eyes of acute angle closure glaucoma, and 23 eyes with chronic angle closure glaucoma, were recruited consecutively in our hospital. All subjects underwent anterior scanning by AS-OCT and UBM. Peripheral iris thickness (PIT) and iris curvature (IC) in the anterior segment image obtained by AS-OCT and UBM were measured twice. The reproducibility of these two scans was evaluated by the intraclass correlation coefficient (ICC). A paired t-test was used to compare the difference between the two scans and the 95% limits of agreement (LoA) were calculated. Results:The ICCs of PIT and IC measured by UBM were 0.892 and 0.936 respectively, while for AS-OCT these values were 0.629 and 0.859, respectively. UBM had a higher reproducibility in both PIT and IC measurements as compared with AS-OCT.Differences in PIT measurement between AS-OCT and UBM(P=0.331).were not statistically significant, the 95% LoA (-0.178～0.156) mm was 36.1～41.2% of the mean. The IC was 0.053 mm smaller when measured by UBM than by AS-OCT (P=0.017), with the 95% LoA (-0.100～0.206) mm, or 36.2～74.6% of the mean.Conclusion:UBM had a higher reproducibility in measuring iris parameters than AS-OCT. The consistency between AS- OCT and UBM in measuring iris parameters was low in primary angle closure glaucoma patients. (Eye Science 2013; 28:1-6)

Influence of Small Cr Addition on Thermal Stability and Magnetic Properties of Fe-Co-Zr-Nb-B Glassy Alloys

Fe62Cos-xCrxZr6Nb4B20 （x=0-4 at. pct） metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both as and He.

Texture Evolution in Heavily Cold-Rolled FeCo-2V Alloy during Annealing

The recrystallization texture evolution in heavily cold-rolled （93%） FeCo-2V alloy with annealing temperature and time was investigated by X-ray diffraction and electron backscatter diffraction. It was found that the orientation density of α-fiber texture component fluctuates with increasing annealing temperature and time. The transmission electron microscopy images show that abundant precipitates appear inside the recrystallized grains and around the grain boundaries. The amount and size of the precipitates also vary with annealing temperature and time. The enhancement of the α-fiber coincides well with the increase of number density of fine precipitates, indicating that the fine precipitates facilitate the development of α-fiber. The annealing texture evolution observed in the FeCo alloy could be attributed to the facilitating effect of the precipitates on the development of α-fiber and the ordering process.

The effect of dislocations on the thermodynamic properties of Ta single crystal under high pressure by molecular dynamics simulation

The thermodynamic properties of Ta metal under high pressure are studied by molecular dynamics simulation. For dislocation-free Ta crystal, all the thermodynamic properties considered are in good agreement with the results from exper- iments or higher level calculations. If dislocations are included in the Ta crystal, it is found that as the dislocation density increases, the hydrostatic pressure at the phase transition point of bcc-＋hcp and hcp--＋fcc decreases, while the Hugoniot temperature increases. Meanwhile, the impact pressure at the elastic-plastic transition point is found to depend on the crys- tallographic orientation of the pressure. As the dislocation density increases, the pressure of the elastic-plastic transition point decreases rapidly at the initial stage, then gradually decreases with the increase of the dislocation density.

Novel Si/SiC heterojunction lateral double-diffused metal-oxide semiconductor field-effect transistor with p-type buried layer breaking silicon limit

A novel silicon carbide(SiC) on silicon(Si) heterojunction lateral double-diffused metal-oxide semiconductor fieldeffect transistor with p-type buried layer(PBL Si/SiC LDMOS) is proposed in this paper for the first time.The heterojunction has breakdown point transfer(BPT) characteristics,and the BPT terminal technology is used to increase the breakdown voltage(BV) of Si/SiC LDMOS with the deep drain region.In order to further optimize the surface lateral electric field distribution of Si/SiC LDMOS with the deep drain region,the p-type buried layer is introduced in PBL Si/SiC LDMOS.The vertical electric field is optimized by Si/SiC heterojunction and the surface lateral electric field is optimized by the p-type buried layer,which greatly improves the BV of device and alleviates the relationship between BV and specific on-resistance(R_(on,sp)).Through TCAD simulation,when the drift region length is 20 μm,the BV is significantly improved from 249 V for the conventional Si LDMOS to 440 V for PBL Si/SiC LDMOS,increased by 77%;And the BV is improved from 384 V for Si/SiC LDMOS with the deep drain region to 440 V for the proposed structure,increased by 15%.The figure-of-merit(FOM) of the Si/SiC LDMOS with the deep drain region and PBL Si/SiC LDMOS are 4.26 MW/cm^(2) and 6.37 MW/cm^(2),respectively.For the PBL Si/SiC LDMOS with the drift length of 20 μm,the maximum FOM is 6.86 MW/cm^(2).The PBL Si/SiC LDMOS breaks conventional silicon limit.

Retinal damage after exposure to white light emitting diode lights at different intensities in Sprague-Dawley rats

Background:The usage of the light emitting diode(LED)has been increasingly applied in the illumination setting and electronic equipment.However,the effect of LED lights on the retina remains unclear.In this study,we observed and analyzed the impact of white LED lights at different intensities on the function and morphology of rat retinas.Methods:Thirty-six Sprague-Dawley rats weighing 150-180 g were randomly divided into six groups(n=6 in each group)including a normal control(NC)group,4 white LED groups at different light intensities(4,000,6,000,7,000,and 10,000 lux),and an ultraviolet B(UVB)lighting group(302 nm,1,000μw/cm2).After 24 hours of continuous illumination,full-field flash electroretinogram(FERG)and pathological examination were performed in each group.Results:As revealed by FERG,the impairment of retinal function gradually worsened with the increase of LED light intensity.In contrast,the UVB group had the most severe retinal function impairment.Particularly,the functional damage of rod cells and inner nuclear layer cells was the main FERG finding in each group.In the NC group,the retina had typical morphologies featured by well-defined structures,clearly visible border between the inner and outer segments,and neatly arranged inner and outer nuclear layer cells.After 24 hours of illumination,the inner and outer parts of the retina in the 4,000 lux group were still neatly arranged,along with a clear border;however,the inner and outer nuclear layers were randomly arranged,and some irregular nuclei and cells were lost.The damage of the internal and external retinal segments and the internal and external nuclear layers became more evident in the 6,000 lux group,7,000 lux group,and 10,000 lux group.The UVB group had a more obviously disordered arrangement of inner and outer nuclear layers and loss of cells.Conclusions:Continuous exposure to white LED light can cause structural and functional damage to rat retinas,and such damage is related to the intensity of illumination.Therefore,the risk of retinal damage should be considered during LED illumination,and proper LED illumination intensity may help to maintain eye health.

Sirolimus eye drops inhibit acute alkali-burn-induced corneal neovascularization by regulating VEGFR2 and caspase-3 expressions

Background:To investigate the effect of sirolimus(SRL)eye drops on acute alkali-burn-induced corneal neovascularization(CNV)and explore its possible mechanism.Methods:A total of 57 male Sprague-Dawley rats weighing 160-180 g were randomly divided into four groups including a normal control group(NC group,n=12),an untreated alkali-burned model control group(MC group,n=15),a blank eye drop treatment group(BT group,n=15),and an SRL eye drop treatment group(ST group,n=15).Corneal inflammation and CNV were observed and scored under a slit-lamp microscope 3,7,and 14 days after alkali exposure.Three rats were randomly sacrificed in each group before modeling and 3,7,14 days after modeling,and the corneas of right eyes were harvested for Western blotting to compare the expression levels of VEGFR2 and caspase-3.Results:Corneal inflammation scoring showed that the corneal edema and conjunctival congestion were severe in the MC,BT,and ST groups 1 day after alkali exposure but were alleviated at day 3.The corneal transparency was significantly higher in the ST group than in the MC and BT groups at days 7(F=9.77,P<0.05)and 14(F=5.81,P<0.05).At day 1,the corneal limbal vascular network was markedly filled.SNV was obvious at days 3,7,and 14.The new blood vessels were shorter and sparser in the ST group than in the MC and BT groups,and the CNV scores showed significant differences among these groups(day 3:F=8.60,P<0.05;day 7:F=11.40,P<0.05;and day 14:F=41.59,P<0.01).Western blotting showed that the expressions of VEGFR2 and caspase-3 were low before modeling and showed no significant difference among the different groups(F=0.52,P>0.05;F=0.98,P>0.05).The corneal expression of VEGFR2 became significantly higher in the MC and BT groups than in the ST group 3,7,and 14 days after alkali exposure,and there were significant differences in relative gray-scale values among these groups(day 3:F=32.16,P<0.01;day 7:F=85.96,P<0.01;day 14:F=57.68,P<0.01).The increase in the corneal expression of caspase-3 was significantly larger in the ST group than in the MC and BT groups at days 3,7,and 14,and there were significant differences in relative gray-scale values among groups(day 3:F=32.16,P<0.01;day 7:F=53.02,P<0.01;day 14:F=38.67,P<0.01).Conclusions:SRL eye drops can alleviate acute alkali-burn-induced corneal inflammation and inhibit alkali-burn-induced CNV in rat models.It can reduce VEGFR2 expression and increase caspase-3 expression in the corneal tissue,which may contribute to the inhibition of alkali-burn-induced CNV.

Research on work mode of university ideological and political education based on SNS network

The education of Ideological and political education in universities have a bidirectional communication, the equal interaction based on network SNS; it can timely warning and regular notification service platform, has become the new channel and new means of Ideological and political education work, strengthening the network of Ideological and political education is an important part to promote the project of ideological and political education reform of College students. The current college ideological and political education has not paid enough attention to network education based on SNS, the position of network construction is lagging behind, the network Ideological and political education lack scientific planning, lack supervision power of social networking and other issues. This paper briefly introduced the University Network Ideological and political education pattern based on SNS, in order to effectively enhance the influence, attraction and control force of network Ideological and political education.

Biomimetic Corrugated Silicon Nanocone Arrays for Self-Cleaning Antireflection Coatings

Corrugated silicon nanocone(SiNC)arrays have been fabricated on a silicon wafer by two polystyrene-sphere-monolayer-masked etching steps in order to create high-performance antireflective coatings.The reflectance was reduced from above 35%to less than 0.7%in the range 400-1050 nm,and it remained below 0.5%at incidence angles up to 70°at 632.8 nm for both s-and p-polarized light.The fluorinated corrugated SiNC array surface exhibits superhydrophobic properties with a water contact angle of 164°.

Highly effective and reproducible surface-enhanced Raman scattering substrates based on Ag pyramidal arrays

Close-packed Ag pyramidal arrays have been fabricated by using inverted pyramidal pits on Si as a template and used to generate plentiful and homogeneous surface-enhanced Raman scattering （SERS） hot sites. The sharp nanotip and the four edges of the Ag pyramid result in strong electromagnetic field enhancement with an average enhancement factor （EF） of 2.84 × 10^7. Moreover, the features of the close-packed Ag pyramidal array can be well controlled, which allows SERS substrates with good reproducibility to be obtained. The relative standard deviation （RSD） was lower than 8.78% both across a single substrate and different batches of substrates.

Rapid estimation of an earthquake impact area using a spatial logistic growth model based on social media data

Rapid estimates of impact areas following large earthquakes constitute the cornerstone of emergency response scenarios.However,collecting information through traditional practices usually requires a large amount of manpower and material resources,slowing the response time.Social media has emerged as a source of real-time‘citizen-sensor data’for disasters and can thus contribute to the rapid acquisition of disaster information.This paper proposes an approach to quickly estimate the impact area following a large earthquake via social media.Specifically,a spatial logistic growth model(SLGM)is proposed to describe the spatial growth of citizen-sensor data influenced by the earthquake impact strength after an earthquake;a framework is then developed to estimate the earthquake impact area by combining social media data and other auxiliary data based on the SLGM.The reliability of our approach is demonstrated in two earthquake cases by comparing the detected areas with official intensity maps,and the time sensitivity of the social media data in the SLGM is discussed.The results illustrate that our approach can effectively estimate the earthquake impact area.We verify the external validity of our model across other earthquake events and provide further insights into extracting more valuable earthquake information using social media.

Reduced water dissociation barrier on constructing Pt-Co/CoO_(x)interface for alkaline hydrogen evolution

Water dissociation process is generally regarded as the rate-limiting step for alkaline hydrogen evolution reaction(HER),and severely inhibits the catalytic efficiency of Pt based catalysts.To overcome this problem,the in-situ constructed interfaces of PtCo alloy and amorphous cobalt oxide(CoO_(x))on the carbon powder are designed.The amorphous CoO_(x)at Pt-Co/CoO_(x)interfaces not only provide active sites for water dissociation to facilitate Volmer step,but also produce the strong electronic transfer with Pt-Co.Accordingly,the obtained interfacial catalysts exhibit outstanding alkaline HER performance with a Tafel slope of 29.3 mV·dec^(−1)and an ultralow overpotential of only 28 mV at 10 mA·cm^(−2).Density functional theory(DFT)reveals that the electronic accumulation on the interfacial Co atom in Pt-Co/CoO_(x)constructing the novel active site for water dissociation.Compared to the Pt-Co,all of the energy barriers for water adsorption,water dissociation and hydrogen adsorption/desorption are reduced in Pt-Co/CoO_(x)interfaces,suggesting a boosted HER kinetics for alkaline HER.

Plastic accommodation during tensile deformation of gradient structure

Gradient structure(GS)possesses a typical trans-scale grain hierarchy with varying internal plastic stability,and the mutual plastic accommodation plays a crucial role in its superior strength-ductility combination.Using the in-situ synchrotron X-ray diffraction(XRD)during tensile loading,we measured lattice strains sequentially from the nanostructured(NS)surface layer to the central coarsegrained(CG)layer to elucidate when and how plastic accommodation occurs and evolves within the GS,along with their roles in plastic deformation and strain hardening.Throughout the tensile deformation,two types of plastic incompatibility occur in the GS.One is an extended elastoplastic transition due to layer-by-layer yielding.The other is strain localization and softening in the NS layer,in contrast with the stable plastic deformation in the CG layer.Plastic accommodation thus occurs concurrently and manifests as both an inter-layer and intra-layer change of stress state throughout tensile deformation.This produces different micromechanical responses between layers.Specifically,the NS layer initially experiences strain hardening followed by an elastoplastic deformation.The hetero-deformation induced hardening,along with forest hardening,facilitates a sustainable tensile strain in the NS layer,comparable to that in the CG layer.

Phase Evolution and Thermal Expansion Behavior of aγ′Precipitated Ni-Based Superalloy by Synchrotron X-Ray Diffraction

The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchrotron X-ray diffraction is able to go through the interior of sample and can be carried out with in situ environment,and thus,it can obtain more statistics information in real time comparing with traditional methods,such as electron and optical microscopies.In this study,in situ heating synchrotron X-ray diffraction was carried out to study the phase evolution in a typicalγ′phase precipitation strengthened Ni-based superalloy,Waspaloy,from 29 to 1050°C.Theγ′,γ,M_(23)C_(6)and M C phases,including their lattice parameters,misfits,dissolution behavior and thermal expansion coefficients,were mainly investigated.Theγ′phase and M_(23)C_(6)carbides appeared obvious dissolution during heating and re-precipitated when the temperature dropped to room temperature.Combining with the microscopy results,we can indicate that the dissolution of M_(23)C_(6)leads to the growth of grain andγ′phase cannot be completely dissolved for the short holding time above the solution temperature.Besides,the coefficients of thermal expansions of all the phases are calculated and fitted as polynomials.

A NOVEL DRIVING STRATEGY FOR DYNAMIC SIMULATION OF HOISTING ROPE WITH TIME-VARYING LENGTH

A simulation method for investigating the vibration behavior of hoisting rope with time-varying length is improved.By previously creating markers in the MSC.ADAMS software package,the parametric model of the rope wound along helix is established based on the concentrated-mass theory with multi-degree of freedom(multi-DOF).A novel driving strategy,cooperating fixed joints with angle sensors under the control of driving script,is proposed to substitute conventional contact force.Researching on the hoisting rope in the sinking winch mechanism,an equivalent discretization model is obtained with complicated boundary conditions considered.The differential equations of motion of the hoisting system are formulated employing Lagrange’s equation and numerically solved using Runge–Kutta method.The simulation indicates that the horizontal swing is decreased in principle and the simulation with 800 discrete ropes is not performed more than 61 min.Therefore,this feasible strategy could not only guarantee the accuracy but also promote simulation efficiency and stability.The motion curves exported from ADAMS simulation coincide with one in numerical simulation,which validates both the numerical model and the driving strategy.

Ultrahigh tensile strength achieved in a lightweight medium Mn steel via prominent work hardening

We develop a new ultrastrong medium Mn steel with a density reduced to 7.39 g cm^(-3).It has a novel tri-phase microstructure comprising a hierarchical martensitic matrix(α’),dispersed ultra-fine-retained austenite grains(γ),and both compressed and{200}orientedδ-ferrite lamellas,the latter’s formation is due to the alloying of high Al and Si contents for reducing density.As a result,both ultrahigh ultimate tensile strength of 2.1 GPa and good ductility of 16%are achieved after an extraordinary plastic strain hardening increment of about 1.4 GPa.The in-situ synchrotron-based high-energy(HE)X-ray diffraction(XRD)examinations during the tensile deformation revealed that the initial presence of residual com-pressive stress inδ-ferrite could increase the stress required to initiate the plastic tensile deformation of the specimen,leading to the isolatedδ-ferrite lamellas mostly deformed elastically to coordinate the plastic deformation of the martensitic matrix during yielding.During the plastic deformation,the gradual release of residual compressive stress inδandα’,the dislocation multiplication in all the three phases and the successiveγ-to-α’transformation all contribute to such a prominent work hardening increment.This study facilitates the development of novel strategies for fabricating ultrastrong but light steels.