In this work,we proposed a method to enhance the magnetic properties of(Nd,Ce)-Fe-B magnets with Ce/TRE ratios below 25 wt%by introducing a moderate amount of La elements.The segregation behavior of La elements toward...In this work,we proposed a method to enhance the magnetic properties of(Nd,Ce)-Fe-B magnets with Ce/TRE ratios below 25 wt%by introducing a moderate amount of La elements.The segregation behavior of La elements towards grain boundaries(GBs)was utilized to optimize the GB phase structure.Incorporation of La atoms into the main phase induces lattice expansion,leading to an increased formation of Ce^(3+)ions with enhanced magnetic moments.Comparative analysis with the original magnet(La/Ce=0 wt%)demonstrates that the magnet with a La/Ce ratio of 10 wt%exhibits improvements of 0.3%in remanence,12.6%in coercivity,and 0.6%in maximum energy produ ct.These results underscore that the moderate addition of La elements enhances the fluidity of the rare earth-rich phase and optimizes the distribution of lamellar GB,consequently reinforcing the magnetic isolation effect.Furthermore,the promotion of the transformation from Ce^(4+)to Ce^(3+)ons contributes to the comprehensive enhancement of the magnetic properties.This research offers a novel strategy for fabricating high-performance and resource-e fficient sintered magnets based on LaCe alloys.展开更多
Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(...Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(NFM30-N)for the oxygen evolution reaction(OER)using a facile top-down approach that combines arc melting with dealloying-oxidation.Due to the dealloying-oxidation effect,the asderived porous amorphous M-O,M-OH,and M-OOH(M=Ni,Fe)nanocones cover the basic NiFeMn alloy.This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities,requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm^(-2),respectively.It also displays a small Tafel slope of 44.1 mV dec^(-1) and remarkable stability for over 100 h at 100 and 500 mA cm^(-2).When used as an anode,a two-electrode electrolyzer cell with NFM30-N at 500 mA cm^(-2) only requires a cell voltage of 1.619 V and exhibits excellent stability,with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm^(-2).This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability,the presence of numerous active sites due to dealloying and the amorphous structure,and the promotion of the OER process by M-O,M-OH,and M-OOH species.This work offers a novel idea for fabricating integrated,industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.展开更多
Organisms are capable of self-growth through the integration of the nutrients provided by the external environment.This process slows down when they grow.In this study,we mimicked this self-regulated growth via a simp...Organisms are capable of self-growth through the integration of the nutrients provided by the external environment.This process slows down when they grow.In this study,we mimicked this self-regulated growth via a simple swelling-polymerization strategy in which the stretching polymer chains in the original networks provide entropic elasticity to restrict growth in high growth cycles.Using typical covalently crosslinked polymers,such as acrylamide-based hydrogels and HBA-based elastomers,as examples,we demonstrate that the crosslinked polymers can absorb polymerizable compounds through a swelling-polymerization process to expand their sizes,but the growth extent becomes smaller with increasing growth cycle until reaching a plateau.In addition to their size,these materials become stiffer and exhibit less swelling ability in solvents.Our work not only provides a new growing mode to tune the properties of crosslinked polymers but also discloses the underlying mechanism of crosslinked polymers in multi-cyclic swelling conditions.展开更多
Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications ...Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications such as catalysts,mi-crowave absorption materials,and enhanced permeability dielectric.The understanding of the mechani-cal properties and dynamics at the atomic scale of the Al_(2)O_(3)/FeCo in-terface can promote the design and exploitment of metal-ceramic composites.In this work,we have obtained Young’s modulus and diffusion coefficient of the Al_(2)O_(3)/FeCo interface using molecular dynamics simulation,elucidated the structural characteristics of the Al_(2)O_(3)/FeCo interface at the atomic scale,and investigated the impact of atomic magnetism and the exter-nal magnetic field on the interface.Simulated results show that Young’s modulus of the Al_(2)O_(3)/FeCo interface is significantly improved compared with pure Al_(2)O_(3)and FeCo alloy at room and high temperatures.When the atomic magnetism and the external magnetic field are applied,Young’s modulus of the Al_(2)O_(3)/FeCo interface further increases to 612 GPa at 300 K and 602 GPa at 500 K.Moreover,the average density,diffusion coefficient,and radial distri-bution function are found to be modified substantially.This study will shed light on the atom-istic investigations of the metal-ceramic composites.展开更多
Direct,in situ selective detection of intracellular formaldehyde(FA)is of great significance for understanding its function in FA-related diseases.Herein,red carbon dots(RCD)are reported as label-free two-photon fluor...Direct,in situ selective detection of intracellular formaldehyde(FA)is of great significance for understanding its function in FA-related diseases.Herein,red carbon dots(RCD)are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA.Upon addition of FA,the-NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water.In addition,the nanoprobes exhibit outsta nding photo stability,rapid response(<1 min),high sensitivity(~9.9μmol/L)and excellent selectivity toward FA over other aldehyde group compounds.Notably,owing to the good cell-membrane permeability and biocompatibility,as well as the large two-photon absorption cross-section,the as-prepared RCD can be used as label-free nanoprobes for selectively detecting and imaging FA in living cells and zebrafishes through one-photon and two-photon excitation.Moreover,RCD could stain the tissue of zebrafishes at depths interval of up to 240μm under two-photon excitation.This research implied that RCD are promising tools for directly and in situ imaging FA in vivo,thus providing critical insights into FA-related pathophysiological processes.展开更多
Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achiev...Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achieving HS in aluminum alloy can be quite challenging.In this study,7000 series alu-minum alloys are investigated by incorporating rare earth element Y to develop a dual-phase structure containing Al_(8)Cu_(4)Y and Al_(3)(Y,Zr)phases.And a heterogeneous lamella structure(HLS)is formed through the synergistic effect of Al_(8)Cu_(4)Y which includes dynamic recrystallization nucleation during deformation,and Al_(3)(Y,Zr)which hinders the growth of recrystallized grain by means of pinning dislocations and sub-grain boundaries.Substructures such as precipitates and nanocrystals are incorporated during the fabri-cation of HS,allowing for precise control over the volume fraction of fine grains by adjusting the ratio of two-scale second phases.When Y content reaches 0.3%,the 7Y55-2/heterogeneous lamella structure(HLS)samples exhibit a fine grain volume fraction of 76.5 vol.%,a tensile strength of 695 MPa,and an elon-gation of 16.6%.The alloy contains a large number of dislocations that preferentially induce the growth ofη’phases along specific directions,thereby promoting their development.The multi-coupling effect and composite strengthening mechanisms in the“heterostructure-dislocation-precipitate”microstructure contribute to the intrinsic excellent strength and plasticity of the alloy.This study tackles the challenge of inverted strength and plasticity observed in Al-Zn-Mg-Cu-Zr alloys,offering novel insights that pave the way for further applications of heterogeneous materials.展开更多
During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni forc...During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni force,However,there is few in situ study investigating kinetics behavior to analyze the forces on droplets.The mechanism of droplet motion remains unclear due to the unavailability or uncertainty of the effect of convection and solutal Marangoni force on droplet behavior.In this study,directional solidification of im-miscible Al-Bi alloy was observed via synchrotron radiography,and the horizontal oscillation of droplets at S/L interface was detected for the first time.Forces,especially solutal Marangoni force,were calcu-lated based on the in situ measured radius of droplets and thermal-solutal gradients.The experimental results cannot be reasonably explained by the previous analysis model which neglects melt convection.The non-negligible effect of flow on droplet motion was demonstrated,and the force balance of droplet both vertically and horizontally can be obtained considering a lift force of 6.39 × 10^(-9) N and a modified solute-related parameter dσ/dc of 0.45-0.65 J m^(-2),respectively.展开更多
The effects of 1Zn and/or 2Ag additions on the hot tearing susceptibility(HTS)of Mg-14Gd-0.4Zr(wt%)alloy were studied.The HTS was evaluated by both theoretical predictions using Kou's criterion and experimental ob...The effects of 1Zn and/or 2Ag additions on the hot tearing susceptibility(HTS)of Mg-14Gd-0.4Zr(wt%)alloy were studied.The HTS was evaluated by both theoretical predictions using Kou's criterion and experimental observations based on the in situ force-temperature recorded constrained rod casting(ISFTCRC)method.The results show that the order of HTS from high to low is Mg-14Gd-2Ag-1Zn-0.4Zr,Mg-14Gd-2Ag-0.4Zr,Mg-14Gd-1Zn-0.4Zr and Mg-14Gd-0.4Zr.Adding 1Zn and/or 2Ag changes the solidification path and the solidification interval,which affects the hot tearing susceptibility.Alloying elemental 1Zn slightly increases the solidification interval and the temperature range in the square root of the solid phase fraction(f_(s)^(1/2))range of 0.949-0.995,resulting in a slight increase in the hot tearing susceptibility.The addition of 2Ag drastically widens both the solidification interval and the temperature range in the f_(s)^(1/2)range of 0.949-0.995,thus significantly increasing the hot tearing susceptibility.Compared to the addition of 2Ag alone,the broadening degree of both the solidification interval and the temperature range in the f_(s)^(1/2)range of 0.949-0.995 is greater by adding the composite 2Ag/1Zn,which further promotes the occurrence of hot tearing.A narrower solidification interval and a temperature range in the f_(s)^(1/2)range of 0.949-0.995 result in a lower hot tearing susceptibility.展开更多
In the present work,the effects of Ni doping on the microstructure and mechanical properties of Co-V-Ga high-temperature shape memory alloy have been studied.It has been found thatγphase occurs in the form of precipi...In the present work,the effects of Ni doping on the microstructure and mechanical properties of Co-V-Ga high-temperature shape memory alloy have been studied.It has been found thatγphase occurs in the form of precipitation or even dendrite microstructure when Ni content continuously increases in the alloy.The composition distribution showed the elements Co and Ni segregated in theγphase,while elements V and Ga concentrated in the martensite phase.Moreover,the phase transition temperature increased by Ni-doping in Co-V-Ga alloys due to the increase in e/a of the alloy.However,the abundant presence ofγphase hindered the shear phase transformation and created a large number of grain boundaries to reduce Ms temperature when Ni content continuously increased.In addition,electron backscattered diffraction(EBSD)results verified that the presence ofγphase could hinder the expansion of cracks,and improve the strength and plasticity of the alloy.Furthermore,it could be found the shape memory effect could maintain a relatively high recovery rate when Ni content was within a certain extent.However,the shape memory effect of the alloy significantly decreased in the presence ofγphase with dendrite microstructure.The current research results not only clarify the influence of Ni doping on the microstructure and mechanical behavior of Co-V-Ga alloys,but also provide guidance for element doping to prepare high-temperature shape memory alloys(HTSMAs)with excellent performance.展开更多
This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the s...This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.展开更多
Potassium-ion batteries(PIBs)were recognized for their natural abunda nce,high theoretical output voltage,and the availability of commercialized graphite anodes.However,the development of highperformance manganese-bas...Potassium-ion batteries(PIBs)were recognized for their natural abunda nce,high theoretical output voltage,and the availability of commercialized graphite anodes.However,the development of highperformance manganese-based layered oxide cathodes-a leading candidate for PIB systems-has been fundamentally constrained by irreversible phase transitions(PT)during the cycling process,manifesting as severe structural degradation and capacity fading.This review presents a transformative paradigm integrating machine learning(ML)with multiscale characterization to analyse the complex phase transition mechanisms in Mn-based cathodes.Through systematic ML-driven interrogation of structure-property relationships,we establish quantitative descriptors for phase stability and develop predictive models for transition dynamics.Furthermore,we highlight recent breakthroughs in cross-disciplinary approaches,enabling the rational design of PT-mitigated cathode architectures.By consolidating these insights into a unified knowledge framework,this work provides strategic guidelines for developing structurally robust Mn-based cathodes and outlines future research directions for next-generation PIB systems.展开更多
Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application p...Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application potential in information encryption,anti-counterfeiting,but remained challenging in improving the security.Herein,we described a self-erased time-resolved information encryption via using photoswitchable dual-color fluorescent polymeric nanoparticles(PDFPNs)containing two fluorescence dyes(blue and red)and photochromic spiroxazine derivatives.In view of the different thermo-induced isomerization rates of photochromic spiroxazine derivatives in different flexible substrates,the decoloration rate of PDFPNs can be programmatically tuned by regulating ratio between rigid polymer and flexible polymer.Therefore,after ultraviolet light(UV)irradiation,correct information could only be recognized in preestablished time during the self-erased process.Our results indicated that PDFPNs exhibited fast photo-responsibility(2 min),high fluorescence contrast,well-pleasing photo-reversibility(>20 times),and programmable thermo-responsiveness(24 s-6 h).We thus demonstrated their application in the selferased time-resolved information encryption and anti-counterfeiting with high security.展开更多
In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh enviro...In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh environment leads to significant variations in the shape and size of the defects.To address this challenge,we propose the multivariate time series segmentation network(MSSN),which adopts a multiscale convolutional network with multi-stage and depth-separable convolutions for efficient feature extraction through variable-length templates.To tackle the classification difficulty caused by structural signal variance,MSSN employs logarithmic normalization to adjust instance distributions.Furthermore,it integrates classification with smoothing loss functions to accurately identify defect segments amid similar structural and defect signal subsequences.Our algorithm evaluated on both the Mackey-Glass dataset and industrial dataset achieves over 95%localization and demonstrates the capture capability on the synthetic dataset.In a nuclear plant's heat transfer tube dataset,it captures 90%of defect instances with75%middle localization F1 score.展开更多
This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are...This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are discussed.Composed mainly of near-equimolar refractory elements,RHEAs have superior mechanical properties,especially at high temperatures.However,many of them have limited room-temperature ductility.Much work has been done to solve this trade-off,and some of the RHEAs have the potential to be used for high-temperature applications in the future.In addition to their mechanical properties,RHEAs have other attractive properties,such as biocompatibility and wear resistance,which are discussed.Finally,current problems and future suggestions for RHEAs are discussed.展开更多
The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scan...The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution electron microscopy （HRTEM）. The struc- tural feature was typical of the particle reinforced composites. The HRTEM images revealed that the observed Ag/SnO2 interface was absence of the precipitated phase and the lattice contrast across the interface was clear and sharp. The average particle size of SnO2 in composite was near 50 nm and it was well dispersed in spherical shape. The thermodynamic mechanism of reactive synthesis method was also discussed. The electronic density distribution analysis of the interface showed the charges of Ag atoms transmitted to 0 atoms and the conductivity of the material was also affected. No extra compounds expected such as AgxOy formed at interface. The distribution of electrons was of inequality near the interface which explained why the mechanical property of the metal/ceramic materials was improved but the machining property declined.展开更多
The discovery of new materials is one of the driving forces to promote the development of modern society and technology innovation,the traditional materials research mainly depended on the trial-and-error method,which...The discovery of new materials is one of the driving forces to promote the development of modern society and technology innovation,the traditional materials research mainly depended on the trial-and-error method,which is time-consuming and laborious.Recently,machine learning(ML)methods have made great progress in the researches of materials science with the arrival of the big-data era,which gives a deep revolution in human society and advance science greatly.However,there exist few systematic generalization and summaries about the applications of ML methods in materials science.In this review,we first provide a brief account of the progress of researches on materials science with ML employed,the main ideas and basic procedures of this method are emphatically introduced.Then the algorithms of ML which were frequently used in the researches of materials science are classified and compared.Finally,the recent meaningful applications of ML in metal materials,battery materials,photovoltaic materials and metallic glass are reviewed.展开更多
Based on a unique method to synthesize WC-Co composite powder by in-situ reactions of metal oxides and carbon, the effects of the carbon addition in the initial powders on the phase constitution, microstructure and me...Based on a unique method to synthesize WC-Co composite powder by in-situ reactions of metal oxides and carbon, the effects of the carbon addition in the initial powders on the phase constitution, microstructure and mechanical properties of the cemented carbides were investigated. It is found that with a suitable carbon addition the pure phase constitution can be obtained in the sintered bulk from the composite powder. The mechanical properties of the cemented carbides depend on the phase constitution and the WC grain structure. To obtain the excellent properties of the WC-Co bulk, it is important to obtain the pure phase constitution from the appropriate carbon addition in the initial powders and a suitable grain size.展开更多
The variations of coarse intermetallic particles in hot-extruded 7055 aluminum alloys with 0.041 wt%Fe and 0.024 wt%Si increasing to 0.272 wt%Fe and 0.134 wt%Si were investigated.The particle stimulated nucleation(PSN...The variations of coarse intermetallic particles in hot-extruded 7055 aluminum alloys with 0.041 wt%Fe and 0.024 wt%Si increasing to 0.272 wt%Fe and 0.134 wt%Si were investigated.The particle stimulated nucleation(PSN)behaviors for different kind of coarse particles were detailly analyzed by EBSD.Moreover,the effect of PSN responding to Fe and Si contents on recrystallization and tensile properties of 7055 alloys was evaluated.With increasing Fe and Si contents,the size and number density of coarseη/S particles are reduced,while the number densities of coarse Al7Cu2 Fe and Mg2Si particles are both increased and the coarse Al7Cu2 Fe particles transform from rod-like to irregular.More PSN recrystallized grains with predominant orientations deviated from the extruded fiber textures are stimulated by the irregular Al7Cu2 Fe and Mg2Si particles,because a higher degree of local non-uniform deformation is produced.The rod-like Al7Cu2 Fe particles cause the greatest degree of local non-uniform deformation owing to the largest aspect ratio,but the shape also restricts the area of particle deformation zone(PDZ)resulting in fewer PSN recrystallized grains.The irregularη/S particles give rise to the lowest degree of local non-uniform deformation and fewest PSN recrystallized grains with the major orientations close to the extruded fiber textures.Consequently,despite the number and size of coarseη/S particles are reduced,the proportion of high angle grain boundaries(HAGBs)is increased and the extruded fiber textures are weakened with Fe and Si contents increasing,because of the increased Al7Cu2 Fe and Mg2Si particles.The strength is slightly declined by the weakened<111>//ED(extrusion direction)fiber texture,while the elongation is reduced for a larger number of coarse particles and more HAGBs with higher Fe and Si contents.展开更多
High-energy ball milling has a great influence on the temperature characters of synthetic reaction in Al-TiO2-C system by changing the size,distribution state and wet ability of reactants.Reaction temperature charact...High-energy ball milling has a great influence on the temperature characters of synthetic reaction in Al-TiO2-C system by changing the size,distribution state and wet ability of reactants.Reaction temperature characters（reaction ignition time,ignition temperature time.the maximum temperature and temperature rising rate）were changed by different milling time.The longer the milling time.the earlier the reaction.the quicker the temperature rise and the higher the maximum temperature.When the milling time exceeded 10 hours,the reactivity of reactants was so high that the synthetic reaction could take place at 850℃ directly without a long time pretreatment at 670℃.The microstructure of synthetic composites became uniform and the reinforced particles（TiC and α-Al2O3）became fine with milling time increasing.展开更多
La2O3 and Y2O3 co-doped Mo secondary emitters were prepared by three kinds of doping method combined with high temperature plasma sintering.The secondary electron emission property and microstructure of the cathodes w...La2O3 and Y2O3 co-doped Mo secondary emitters were prepared by three kinds of doping method combined with high temperature plasma sintering.The secondary electron emission property and microstructure of the cathodes were studied.It showed that the cathode prepared by liquid-liquid doping method exhibited the best emission property among all the samples prepared by liquid-solid doping,solid-solid doping and liquid-liquid doping methods due to a uniform distribution of different substances.RE2O3 existed unifo...展开更多
基金Project supported by the National Natural Science Foundation of China(52071004,52301228,51971005,52171168)the Program of Top Disciplines Construction in Beijing(PXM2019_014204_500031)the International Research Cooperation Seed Fund of Beijing University of Technology(2021B23)。
文摘In this work,we proposed a method to enhance the magnetic properties of(Nd,Ce)-Fe-B magnets with Ce/TRE ratios below 25 wt%by introducing a moderate amount of La elements.The segregation behavior of La elements towards grain boundaries(GBs)was utilized to optimize the GB phase structure.Incorporation of La atoms into the main phase induces lattice expansion,leading to an increased formation of Ce^(3+)ions with enhanced magnetic moments.Comparative analysis with the original magnet(La/Ce=0 wt%)demonstrates that the magnet with a La/Ce ratio of 10 wt%exhibits improvements of 0.3%in remanence,12.6%in coercivity,and 0.6%in maximum energy produ ct.These results underscore that the moderate addition of La elements enhances the fluidity of the rare earth-rich phase and optimizes the distribution of lamellar GB,consequently reinforcing the magnetic isolation effect.Furthermore,the promotion of the transformation from Ce^(4+)to Ce^(3+)ons contributes to the comprehensive enhancement of the magnetic properties.This research offers a novel strategy for fabricating high-performance and resource-e fficient sintered magnets based on LaCe alloys.
基金the National Natural Science Foundation of China(Nos.52174365,52004155,52334009 and 52130204)the National Key R&D Program of China(Nos.2023YFB3506701 and 2022YFB3706801)the Science and Technology Commission of Shanghai Municipality(No.21DZ1208900).
文摘Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(NFM30-N)for the oxygen evolution reaction(OER)using a facile top-down approach that combines arc melting with dealloying-oxidation.Due to the dealloying-oxidation effect,the asderived porous amorphous M-O,M-OH,and M-OOH(M=Ni,Fe)nanocones cover the basic NiFeMn alloy.This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities,requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm^(-2),respectively.It also displays a small Tafel slope of 44.1 mV dec^(-1) and remarkable stability for over 100 h at 100 and 500 mA cm^(-2).When used as an anode,a two-electrode electrolyzer cell with NFM30-N at 500 mA cm^(-2) only requires a cell voltage of 1.619 V and exhibits excellent stability,with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm^(-2).This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability,the presence of numerous active sites due to dealloying and the amorphous structure,and the promotion of the OER process by M-O,M-OH,and M-OOH species.This work offers a novel idea for fabricating integrated,industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.
基金financially supported by the National Natural Science Foundation of China(Nos.52203135 and 52273206)Postdoctoral Fellowship Program of CPSF(No.GZC20230372)+4 种基金Huzhou Science and Technology Program Projects(No.2023GZ18)Zhejiang Postdoctoral Research Project(No.ZJ2023133)Science and Technology Cooperation Fund Program of Chengdu-Chinese Academy of ScienceHunan Provincial Natural Science Foundation(No.2021JJ10029)Huxiang High-level Talent Gathering Project(No.2022RC4039)。
文摘Organisms are capable of self-growth through the integration of the nutrients provided by the external environment.This process slows down when they grow.In this study,we mimicked this self-regulated growth via a simple swelling-polymerization strategy in which the stretching polymer chains in the original networks provide entropic elasticity to restrict growth in high growth cycles.Using typical covalently crosslinked polymers,such as acrylamide-based hydrogels and HBA-based elastomers,as examples,we demonstrate that the crosslinked polymers can absorb polymerizable compounds through a swelling-polymerization process to expand their sizes,but the growth extent becomes smaller with increasing growth cycle until reaching a plateau.In addition to their size,these materials become stiffer and exhibit less swelling ability in solvents.Our work not only provides a new growing mode to tune the properties of crosslinked polymers but also discloses the underlying mechanism of crosslinked polymers in multi-cyclic swelling conditions.
基金supported by the National Natural Science Foundation of China(Nos.22173057,52130204,12074241,11929401,12311530675)Science and Technology Commission of Shanghai Municipality(Nos.21JC1402700,22XD1400900,20501130600,21JC1402600)High-Performance Computing Center,Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University。
文摘Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications such as catalysts,mi-crowave absorption materials,and enhanced permeability dielectric.The understanding of the mechani-cal properties and dynamics at the atomic scale of the Al_(2)O_(3)/FeCo in-terface can promote the design and exploitment of metal-ceramic composites.In this work,we have obtained Young’s modulus and diffusion coefficient of the Al_(2)O_(3)/FeCo interface using molecular dynamics simulation,elucidated the structural characteristics of the Al_(2)O_(3)/FeCo interface at the atomic scale,and investigated the impact of atomic magnetism and the exter-nal magnetic field on the interface.Simulated results show that Young’s modulus of the Al_(2)O_(3)/FeCo interface is significantly improved compared with pure Al_(2)O_(3)and FeCo alloy at room and high temperatures.When the atomic magnetism and the external magnetic field are applied,Young’s modulus of the Al_(2)O_(3)/FeCo interface further increases to 612 GPa at 300 K and 602 GPa at 500 K.Moreover,the average density,diffusion coefficient,and radial distri-bution function are found to be modified substantially.This study will shed light on the atom-istic investigations of the metal-ceramic composites.
基金financial support of the present work by the National Natural Science Foundation of China(Nos.51773056,51603067,21705040)Natural Science Foundationof Hunan Province,China(No.2018JJ3143)+3 种基金China Postdoctoral Science Foundation(Nos.2017M622571,2017M622568 and 2018T110824)Open Project Program of State Key Laboratory of Chemo/Biosensing and Chemometrics(No.2016019)Open Fund of the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology)(No.2019-skllmd-09)Natural Science Foundation of Guangdong Province(No.2017A030313299)。
文摘Direct,in situ selective detection of intracellular formaldehyde(FA)is of great significance for understanding its function in FA-related diseases.Herein,red carbon dots(RCD)are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA.Upon addition of FA,the-NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water.In addition,the nanoprobes exhibit outsta nding photo stability,rapid response(<1 min),high sensitivity(~9.9μmol/L)and excellent selectivity toward FA over other aldehyde group compounds.Notably,owing to the good cell-membrane permeability and biocompatibility,as well as the large two-photon absorption cross-section,the as-prepared RCD can be used as label-free nanoprobes for selectively detecting and imaging FA in living cells and zebrafishes through one-photon and two-photon excitation.Moreover,RCD could stain the tissue of zebrafishes at depths interval of up to 240μm under two-photon excitation.This research implied that RCD are promising tools for directly and in situ imaging FA in vivo,thus providing critical insights into FA-related pathophysiological processes.
基金supported by the National Key Research and Development Program of China(No.2023YFB3406800)the National Natural Science Foundation of China(Nos.52271036 and 51971237).
文摘Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achieving HS in aluminum alloy can be quite challenging.In this study,7000 series alu-minum alloys are investigated by incorporating rare earth element Y to develop a dual-phase structure containing Al_(8)Cu_(4)Y and Al_(3)(Y,Zr)phases.And a heterogeneous lamella structure(HLS)is formed through the synergistic effect of Al_(8)Cu_(4)Y which includes dynamic recrystallization nucleation during deformation,and Al_(3)(Y,Zr)which hinders the growth of recrystallized grain by means of pinning dislocations and sub-grain boundaries.Substructures such as precipitates and nanocrystals are incorporated during the fabri-cation of HS,allowing for precise control over the volume fraction of fine grains by adjusting the ratio of two-scale second phases.When Y content reaches 0.3%,the 7Y55-2/heterogeneous lamella structure(HLS)samples exhibit a fine grain volume fraction of 76.5 vol.%,a tensile strength of 695 MPa,and an elon-gation of 16.6%.The alloy contains a large number of dislocations that preferentially induce the growth ofη’phases along specific directions,thereby promoting their development.The multi-coupling effect and composite strengthening mechanisms in the“heterostructure-dislocation-precipitate”microstructure contribute to the intrinsic excellent strength and plasticity of the alloy.This study tackles the challenge of inverted strength and plasticity observed in Al-Zn-Mg-Cu-Zr alloys,offering novel insights that pave the way for further applications of heterogeneous materials.
基金National Natural Science Foundation of China(Nos.52271036 and 51971237)Shanghai Pujiang Program(No.21PJD030)。
文摘During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni force,However,there is few in situ study investigating kinetics behavior to analyze the forces on droplets.The mechanism of droplet motion remains unclear due to the unavailability or uncertainty of the effect of convection and solutal Marangoni force on droplet behavior.In this study,directional solidification of im-miscible Al-Bi alloy was observed via synchrotron radiography,and the horizontal oscillation of droplets at S/L interface was detected for the first time.Forces,especially solutal Marangoni force,were calcu-lated based on the in situ measured radius of droplets and thermal-solutal gradients.The experimental results cannot be reasonably explained by the previous analysis model which neglects melt convection.The non-negligible effect of flow on droplet motion was demonstrated,and the force balance of droplet both vertically and horizontally can be obtained considering a lift force of 6.39 × 10^(-9) N and a modified solute-related parameter dσ/dc of 0.45-0.65 J m^(-2),respectively.
基金Project supported by the National Natural Science Foundation of China(U2037601,52074183)Shanghai Sailing Program(23YF1417100)。
文摘The effects of 1Zn and/or 2Ag additions on the hot tearing susceptibility(HTS)of Mg-14Gd-0.4Zr(wt%)alloy were studied.The HTS was evaluated by both theoretical predictions using Kou's criterion and experimental observations based on the in situ force-temperature recorded constrained rod casting(ISFTCRC)method.The results show that the order of HTS from high to low is Mg-14Gd-2Ag-1Zn-0.4Zr,Mg-14Gd-2Ag-0.4Zr,Mg-14Gd-1Zn-0.4Zr and Mg-14Gd-0.4Zr.Adding 1Zn and/or 2Ag changes the solidification path and the solidification interval,which affects the hot tearing susceptibility.Alloying elemental 1Zn slightly increases the solidification interval and the temperature range in the square root of the solid phase fraction(f_(s)^(1/2))range of 0.949-0.995,resulting in a slight increase in the hot tearing susceptibility.The addition of 2Ag drastically widens both the solidification interval and the temperature range in the f_(s)^(1/2)range of 0.949-0.995,thus significantly increasing the hot tearing susceptibility.Compared to the addition of 2Ag alone,the broadening degree of both the solidification interval and the temperature range in the f_(s)^(1/2)range of 0.949-0.995 is greater by adding the composite 2Ag/1Zn,which further promotes the occurrence of hot tearing.A narrower solidification interval and a temperature range in the f_(s)^(1/2)range of 0.949-0.995 result in a lower hot tearing susceptibility.
基金supported by the National Key R&D Program of China(Nos.2023YFB3506701 and 2022YFB3706801)the National Natural Science Foundation of China(Nos.52174365,52004155,and 52130204).
文摘In the present work,the effects of Ni doping on the microstructure and mechanical properties of Co-V-Ga high-temperature shape memory alloy have been studied.It has been found thatγphase occurs in the form of precipitation or even dendrite microstructure when Ni content continuously increases in the alloy.The composition distribution showed the elements Co and Ni segregated in theγphase,while elements V and Ga concentrated in the martensite phase.Moreover,the phase transition temperature increased by Ni-doping in Co-V-Ga alloys due to the increase in e/a of the alloy.However,the abundant presence ofγphase hindered the shear phase transformation and created a large number of grain boundaries to reduce Ms temperature when Ni content continuously increased.In addition,electron backscattered diffraction(EBSD)results verified that the presence ofγphase could hinder the expansion of cracks,and improve the strength and plasticity of the alloy.Furthermore,it could be found the shape memory effect could maintain a relatively high recovery rate when Ni content was within a certain extent.However,the shape memory effect of the alloy significantly decreased in the presence ofγphase with dendrite microstructure.The current research results not only clarify the influence of Ni doping on the microstructure and mechanical behavior of Co-V-Ga alloys,but also provide guidance for element doping to prepare high-temperature shape memory alloys(HTSMAs)with excellent performance.
基金the National Elite Foundationthe Institute for Advanced Studies in Basic Sciences for their financial supportfinancially supported by the National Natural Science Foundation of China(22173026,22350410386,22375200,U22A202175,21961142006)。
文摘This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.
基金financially supported by the National Natural Science Foundation of China(U20A20247)the National Key Research and Development Program of the Ministry of Science and Technology(2022YFA1402504)+1 种基金Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion(MATEC2023KF002)Guangdong Science and Technology Department(STKJ2021016)。
文摘Potassium-ion batteries(PIBs)were recognized for their natural abunda nce,high theoretical output voltage,and the availability of commercialized graphite anodes.However,the development of highperformance manganese-based layered oxide cathodes-a leading candidate for PIB systems-has been fundamentally constrained by irreversible phase transitions(PT)during the cycling process,manifesting as severe structural degradation and capacity fading.This review presents a transformative paradigm integrating machine learning(ML)with multiscale characterization to analyse the complex phase transition mechanisms in Mn-based cathodes.Through systematic ML-driven interrogation of structure-property relationships,we establish quantitative descriptors for phase stability and develop predictive models for transition dynamics.Furthermore,we highlight recent breakthroughs in cross-disciplinary approaches,enabling the rational design of PT-mitigated cathode architectures.By consolidating these insights into a unified knowledge framework,this work provides strategic guidelines for developing structurally robust Mn-based cathodes and outlines future research directions for next-generation PIB systems.
基金financially supported by the National Key R&D Program of China(Nos.2023YFB3812400,2023YFB3812403)National Natural Foundation of China(Nos.52273206,52350233)+1 种基金Hunan Provincial Natural Science Foundation(No.2021JJ10029)Huxiang High-level Talent Gathering Project(No.2022RC4039).
文摘Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application potential in information encryption,anti-counterfeiting,but remained challenging in improving the security.Herein,we described a self-erased time-resolved information encryption via using photoswitchable dual-color fluorescent polymeric nanoparticles(PDFPNs)containing two fluorescence dyes(blue and red)and photochromic spiroxazine derivatives.In view of the different thermo-induced isomerization rates of photochromic spiroxazine derivatives in different flexible substrates,the decoloration rate of PDFPNs can be programmatically tuned by regulating ratio between rigid polymer and flexible polymer.Therefore,after ultraviolet light(UV)irradiation,correct information could only be recognized in preestablished time during the self-erased process.Our results indicated that PDFPNs exhibited fast photo-responsibility(2 min),high fluorescence contrast,well-pleasing photo-reversibility(>20 times),and programmable thermo-responsiveness(24 s-6 h).We thus demonstrated their application in the selferased time-resolved information encryption and anti-counterfeiting with high security.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(2024ZD0608100)the National Natural Science Foundation of China(62332017,U22A2022)
文摘In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh environment leads to significant variations in the shape and size of the defects.To address this challenge,we propose the multivariate time series segmentation network(MSSN),which adopts a multiscale convolutional network with multi-stage and depth-separable convolutions for efficient feature extraction through variable-length templates.To tackle the classification difficulty caused by structural signal variance,MSSN employs logarithmic normalization to adjust instance distributions.Furthermore,it integrates classification with smoothing loss functions to accurately identify defect segments amid similar structural and defect signal subsequences.Our algorithm evaluated on both the Mackey-Glass dataset and industrial dataset achieves over 95%localization and demonstrates the capture capability on the synthetic dataset.In a nuclear plant's heat transfer tube dataset,it captures 90%of defect instances with75%middle localization F1 score.
基金the National Natural Science Foundation of China(Nos.51871147,51821001)the Shanghai Aerospace Advanced Technology Joint Research Fund,China(No.USCAST2020-35).
文摘This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are discussed.Composed mainly of near-equimolar refractory elements,RHEAs have superior mechanical properties,especially at high temperatures.However,many of them have limited room-temperature ductility.Much work has been done to solve this trade-off,and some of the RHEAs have the potential to be used for high-temperature applications in the future.In addition to their mechanical properties,RHEAs have other attractive properties,such as biocompatibility and wear resistance,which are discussed.Finally,current problems and future suggestions for RHEAs are discussed.
基金supported by the National Natural Science Foundation of China (Nos. 2008CB617609,u0837601, u0837603 and 50874054)the Science Innovation Foundation of Kunming University of Science and Technology
文摘The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution electron microscopy （HRTEM）. The struc- tural feature was typical of the particle reinforced composites. The HRTEM images revealed that the observed Ag/SnO2 interface was absence of the precipitated phase and the lattice contrast across the interface was clear and sharp. The average particle size of SnO2 in composite was near 50 nm and it was well dispersed in spherical shape. The thermodynamic mechanism of reactive synthesis method was also discussed. The electronic density distribution analysis of the interface showed the charges of Ag atoms transmitted to 0 atoms and the conductivity of the material was also affected. No extra compounds expected such as AgxOy formed at interface. The distribution of electrons was of inequality near the interface which explained why the mechanical property of the metal/ceramic materials was improved but the machining property declined.
基金This work was financially supported by the National Natural Science Foundation of China(No.51627802)。
文摘The discovery of new materials is one of the driving forces to promote the development of modern society and technology innovation,the traditional materials research mainly depended on the trial-and-error method,which is time-consuming and laborious.Recently,machine learning(ML)methods have made great progress in the researches of materials science with the arrival of the big-data era,which gives a deep revolution in human society and advance science greatly.However,there exist few systematic generalization and summaries about the applications of ML methods in materials science.In this review,we first provide a brief account of the progress of researches on materials science with ML employed,the main ideas and basic procedures of this method are emphatically introduced.Then the algorithms of ML which were frequently used in the researches of materials science are classified and compared.Finally,the recent meaningful applications of ML in metal materials,battery materials,photovoltaic materials and metallic glass are reviewed.
基金supported by the Chinese National Programs for Fundamental Research and Development (Grant No.2011CB612207)the National Natural Science Foundation of China (Grant No. 51174009)+1 种基金the Program of National Science Infrastructure Platformthe State Key Laboratory of Powder Metallurgy of Central South University
文摘Based on a unique method to synthesize WC-Co composite powder by in-situ reactions of metal oxides and carbon, the effects of the carbon addition in the initial powders on the phase constitution, microstructure and mechanical properties of the cemented carbides were investigated. It is found that with a suitable carbon addition the pure phase constitution can be obtained in the sintered bulk from the composite powder. The mechanical properties of the cemented carbides depend on the phase constitution and the WC grain structure. To obtain the excellent properties of the WC-Co bulk, it is important to obtain the pure phase constitution from the appropriate carbon addition in the initial powders and a suitable grain size.
基金supported financially by the National Natural Science Foundation of China (No.51821001)
文摘The variations of coarse intermetallic particles in hot-extruded 7055 aluminum alloys with 0.041 wt%Fe and 0.024 wt%Si increasing to 0.272 wt%Fe and 0.134 wt%Si were investigated.The particle stimulated nucleation(PSN)behaviors for different kind of coarse particles were detailly analyzed by EBSD.Moreover,the effect of PSN responding to Fe and Si contents on recrystallization and tensile properties of 7055 alloys was evaluated.With increasing Fe and Si contents,the size and number density of coarseη/S particles are reduced,while the number densities of coarse Al7Cu2 Fe and Mg2Si particles are both increased and the coarse Al7Cu2 Fe particles transform from rod-like to irregular.More PSN recrystallized grains with predominant orientations deviated from the extruded fiber textures are stimulated by the irregular Al7Cu2 Fe and Mg2Si particles,because a higher degree of local non-uniform deformation is produced.The rod-like Al7Cu2 Fe particles cause the greatest degree of local non-uniform deformation owing to the largest aspect ratio,but the shape also restricts the area of particle deformation zone(PDZ)resulting in fewer PSN recrystallized grains.The irregularη/S particles give rise to the lowest degree of local non-uniform deformation and fewest PSN recrystallized grains with the major orientations close to the extruded fiber textures.Consequently,despite the number and size of coarseη/S particles are reduced,the proportion of high angle grain boundaries(HAGBs)is increased and the extruded fiber textures are weakened with Fe and Si contents increasing,because of the increased Al7Cu2 Fe and Mg2Si particles.The strength is slightly declined by the weakened<111>//ED(extrusion direction)fiber texture,while the elongation is reduced for a larger number of coarse particles and more HAGBs with higher Fe and Si contents.
文摘High-energy ball milling has a great influence on the temperature characters of synthetic reaction in Al-TiO2-C system by changing the size,distribution state and wet ability of reactants.Reaction temperature characters（reaction ignition time,ignition temperature time.the maximum temperature and temperature rising rate）were changed by different milling time.The longer the milling time.the earlier the reaction.the quicker the temperature rise and the higher the maximum temperature.When the milling time exceeded 10 hours,the reactivity of reactants was so high that the synthetic reaction could take place at 850℃ directly without a long time pretreatment at 670℃.The microstructure of synthetic composites became uniform and the reinforced particles（TiC and α-Al2O3）became fine with milling time increasing.
基金supported by the 863 program of China (2006AA03Z524, 2008AA031001)National Nature Foundation (50801001)Beijing New Century Hundred, Thousand and Ten Thousand Talent Project (Q1009001200802)
文摘La2O3 and Y2O3 co-doped Mo secondary emitters were prepared by three kinds of doping method combined with high temperature plasma sintering.The secondary electron emission property and microstructure of the cathodes were studied.It showed that the cathode prepared by liquid-liquid doping method exhibited the best emission property among all the samples prepared by liquid-solid doping,solid-solid doping and liquid-liquid doping methods due to a uniform distribution of different substances.RE2O3 existed unifo...
