Catalyst–support interaction plays a crucial role in improving the catalytic activity of oxygen evolution reaction(OER).Here we modulate the catalyst–support interaction in polyaniline-supported Ni_(3)Fe oxide(Ni_(3...Catalyst–support interaction plays a crucial role in improving the catalytic activity of oxygen evolution reaction(OER).Here we modulate the catalyst–support interaction in polyaniline-supported Ni_(3)Fe oxide(Ni_(3)Fe oxide/PANI)with a robust hetero-interface,which significantly improves oxygen evolution activities with an overpotential of 270 mV at 10 mA cm^(-2)and specific activity of 2.08 mA cm_(ECSA)^(-2)at overpotential of 300 mV,3.84-fold that of Ni_(3)Fe oxide.It is revealed that the catalyst–support interaction between Ni_(3)Fe oxide and PANI support enhances the Ni–O covalency via the interfacial Ni–N bond,thus promoting the charge and mass transfer on Ni_(3)Fe oxide.Considering the excellent activity and stability,rechargeable Zn-air batteries with optimum Ni_(3)Fe oxide/PANI are assembled,delivering a low charge voltage of 1.95 V to cycle for 400 h at 10 mA cm^(-2).The regulation of the effect of catalyst–support interaction on catalytic activity provides new possibilities for the future design of highly efficient OER catalysts.展开更多
Metallic Zn anodes suffer from hydrogen evolution and dendritic deposition in aqueous electrolytes,resulting in low Coulombic efficiency and poor cyclic stability for aqueous Zn-ion batteries(AZIBs).Constructing stabl...Metallic Zn anodes suffer from hydrogen evolution and dendritic deposition in aqueous electrolytes,resulting in low Coulombic efficiency and poor cyclic stability for aqueous Zn-ion batteries(AZIBs).Constructing stable solid electrolyte interphase(SEI)with strong affinity for Zn and exclusion of water corrosion of Zn metal anodes is a promising strategy to tackle these challenges.In this study,we develop a self-healing ZnO-based SEI film on the Zn electrode surface by employing an aspartame(APM)as a versatile electrolyte additive.The hydrophobic nature and strong Zn affinity of APM can facilitate the dynamic self-healing of ZnO-based SEI film during cyclic Zn plating/stripping process.Benefiting from the superior protection effect of self-healing ZnO-based SEI,the Zn║Cu cells possess an average coulombic efficiency more than 99.59%over 1,000 cycles even at a low current density of 1 m A cm^(-2)-1 m Ah cm^(-2).Furthermore,the Zn║NH_4~+-V_(2)O_5 full cells display a large specific capacity of 150 mAh g^(-1)and high cyclic stability with a capacity retention of 77.8%after 1,750 cycles.In addition,the Zn║Zn cell delivers high temperature adaptability at a wide-temperature range from-5 to 40℃ even under a high DOD of 85.2%.The enhanced capability and durability originate from the self-healing SEI formation enabled by multifunctional APM additives mediating both corrosion suppression and interfacial stabilization.This work presents an inspired and straightforward approach to promote a dendrite-free and widetemperature rechargeable AZIBs energy storage system.展开更多
To fulfill the demands of applications under severe operational conditions,alloys should possess outstanding wear resistance at elevated temperatures.A Ti-Hf-Nb-V based refractory high entropy alloy(RHEA)was successfu...To fulfill the demands of applications under severe operational conditions,alloys should possess outstanding wear resistance at elevated temperatures.A Ti-Hf-Nb-V based refractory high entropy alloy(RHEA)was successfully produced using the directed energy deposition(DED)technique,which avoided the formation of fatal defects and showcased well-performed mechanical properties across a broad temperature spectrum.Strategic design of the oxidation sequence enabled the early formation of oxide nanolayers,which can form a polycrystalline oxide nanocoating under a complex stress condition to drastically reduce the wear rate from 2.69×10^(-4) mm^(3)·(N·m)^(−1) at room temperature to 6.90×10^(-7) mm^(3)·(N·m)^(−1) at 600℃.These results indicate that the application of additive manufacturing to fabricate RHEAs with superior wear resistance at high temperatures paves the way for the development of functional coatings designed to withstand extreme conditions.展开更多
Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain su...Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.展开更多
Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Fur...Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Furthermore,downward salt ion transport is also desired to prevent salt accumulation.However,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal transport.Here,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal transport.The arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss.These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without degradation.Even in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal formation.This work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.展开更多
The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium ma...The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium matrix composites were prepared by discharge plasma sintering(SPS)and argon protective sintering(APS).The results show that the two processes have a negligible effect on the composition and hardness of the samples,but the hardness of the two samples is significantly improved by adding SiCp.The apparent porosity of SPS process is obviously smaller than that of APS process,whereas,the apparent porosity increases slightly with the addition of SiCp.The oxide layer thickness and mass gain of the samples obtained by SPS process are smaller than those obtained by APS process.The oxide thickness and mass gain of both processes are further reduced by adding SiCp.The SPS composites showed the best high temperature oxidation resistance.Therefore,TMCs with Si Cp by SPS can effectively improve the high-temperature oxidation behavior of the materials.展开更多
Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufact...Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufacturing field.To improve the surface quality of the ground workpiece,a new high-shear and low-pressure grinding wheel,with high ratio of tangential grinding force to normal grinding force,was fabricated for the grinding of selective laser melting(SLM)manufactured Inconel718 alloy.The principle of high-shear and low-pressure grinding process was introduced in detail,which was quite different from the conventional grinding process.The fabrication process of the new grinding wheel was illustrated.A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained.The surface roughness of ground workpiece was reduced to 0.232μm from the initial value of 0.490μm under the optimal grinding conditions.It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM).The capability of the newly developed highshear and low-pressure grinding wheel was validated.展开更多
Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition belo...Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition below a critical grain size.In this work,a facile laser surface remelting-based technique was employed and optimized to fabricate a∼600μm-thick heterogeneous gradient nanostructured layer on an austenitic Hadfield manganese steel,in which the average grain size is gradually decreased from∼200μm in the matrix to only∼8 nm in the nanocrystalline-amorphous core-shell topmost surface.Atomic-scale microstructural characterizations dissected the gradient refinement processes along the gradient direction,i.e.transiting from the dislocations activities and twinning in sub-region to three kinds of martensitic transformations,and finally a multi-phase nanocrystalline-amorphous core-shell structural surface.Mechanical tests(e.g.nanoindentation,bulk-specimen tensile,and micro-pillar compression)were conducted along the gradient direction.It confirms a tensile strength of∼1055 MPa and ductility of∼10.5%in the laser-processed specimen.Particularly,the core-shell structural surface maintains ultra-strong(tensile strength of∼1.6 GPa,micro-pillar compressive strength of∼4 GPa at a strain of∼8%,and nanoindentation hardness of∼7.7 GPa)to overcome the potential strengthening-softening transition.Such significant strengthening effects are ascribed to the strength-ductility synergetic effects-induced extra work hardening ability in gradient nanostructure and the well-maintained dislocation activities inside extremely refined nanograins in the multi-phase nanocrystalline-amorphous core-shell structural surface,which are evidenced by atomic-scale observations and theoretical analysis.This study provides a unique hetero-nanostructure through a facile laser-related technique for extraordinary mechanical performance.展开更多
Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics inc...Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in UHSSs.In this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process.This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase.The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni enrichment.The hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)effect.As a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.展开更多
The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp...The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.展开更多
Interstitial alloying has emerged as a powerful strategy to tune microstructure and microproperties of high-entropy alloys(HEAs) due to the strong interaction of interstitials with constituent elements and crystal def...Interstitial alloying has emerged as a powerful strategy to tune microstructure and microproperties of high-entropy alloys(HEAs) due to the strong interaction of interstitials with constituent elements and crystal defects,which enables the development of advanced alloys with superior mechanical and functional properties. The paper reviews the latest progress in the atomic-scale understanding of the effects of various interstitials, including carbon, boron, nitrogen, oxygen, and hydrogen, on the microstructure, stability, mechanical properties, and deformation behavior of HEAs. Emphases are placed on the in-depth insights on the interaction of interstitials with constituent elements and crystal defects, such as vacancies,stacking faults, and grain boundaries. Key parameters for rapid prediction of intrinsic properties of HEAs are also discussed. Finally, we highlight some unsolved issues and provide perspectives for future research directions.展开更多
The intrinsic properties of theγ′phase are well known to be of critical importance for the targeted control of the mechanical performance ofγ/γ′high entropy alloys(HEAs).In the present work,a composition tuning s...The intrinsic properties of theγ′phase are well known to be of critical importance for the targeted control of the mechanical performance ofγ/γ′high entropy alloys(HEAs).In the present work,a composition tuning strategy is employed to modulate the thermal stability,elastic properties,and deformation mechanisms of theγ′phase in(FeCoNi)86Ti7Al7 HEAs using ab initio methods.Prior to tailoring the alloying elements,the temperature-dependent stability of theγ′phase is meticulously investigated by considering both enthalpic and entropic contributions.The findings reveal that the primary vibrational entropy can be effectively substituted by an empirical parameter(δ)to expedite the design of stable HEAs.Subsequently,based on the individual effects of elements on the order-disorder transformation temperatures(Tod)and practical considerations for high-temperature applications,eight substituting elements(Nb,Mo,Ta,W,V,Cr,Mn and Cu)are judiciously selected from the 3d,4d and 5d transition metal series.The results indicate that Nb and Ta are the most ideal substituting elements for theγ′phase,as they concurrently enhance the Tod,shear modulus,hardness,ductility,and antiphase boundary energy.These insights open a promising avenue for the innovative design of strong-yet-ductileγ/γ′HEAs.展开更多
In this study,we demonstrate the direct in-situ synthesis of NiTi alloys with tunable chemical com-position(Ni/Ti atomic ratio)and corresponding thermomechanical response.This synthesis is achieved by regulating the f...In this study,we demonstrate the direct in-situ synthesis of NiTi alloys with tunable chemical com-position(Ni/Ti atomic ratio)and corresponding thermomechanical response.This synthesis is achieved by regulating the feeding speed ratio of pure Ni and Ti wires during the additive manufacturing pro-cess based on dual-wire-feed electron beam directed energy deposition(EB-DED)technology.Under ap-propriate process conditions,the resulting NiTi alloys exhibit a controllable evolution around the near-equiatomic composition and display a typical columnar grain morphology characteristic of additively manufactured NiTi alloys.With an increase in Ni content(shifting from Ti-rich to Ni-rich),the second phase particles present in the samples change from Ti-rich phase(Ti_(2) Ni)to Ni-rich phases(such as Ni4 Ti3 and Ni3 Ti_(2)).The phase transformation temperatures gradually decrease with increasing Ni content,and the predominant matrix phase transitions from martensite to austenite.The as-built NiTi alloy exhibits a typical tensile curve with a good tensile elongation of 11%,fabricated under suitable composition and microstructure conditions.This result surpasses values reported in current in-situ synthesized NiTi alloys through additive manufacturing methods.Moreover,it almost reaches the levels achieved by additively manufactured NiTi alloys using pre-alloyed raw materials.Furthermore,this study reports,for the first time in the field of in-situ synthesized NiTi alloys,a good tensile shape memory effect,achieving an im-pressive recovery rate of up to 70%under a tensile strain of 6%.This investigation provides a meaningful theoretical perspective and technical strategy for the integrated customization of NiTi alloy components in structure,composition,and function.This low-cost and high-efficiency approach is particularly attrac-tive for the preparation of functional graded,large-scale and disposable NiTi components.展开更多
Inspired by bacterial motility mechanisms,Magnetic Helical Miniature Robots(MHMRs)exhibit promising applications in biomedical fields due to their efficient locomotion and compatibility with biological tissues.In this...Inspired by bacterial motility mechanisms,Magnetic Helical Miniature Robots(MHMRs)exhibit promising applications in biomedical fields due to their efficient locomotion and compatibility with biological tissues.In this review,we systematically survey the basics of MHMRs,from propulsion mechanism,magnetization and control methods to biomedical applications,aiming to provide readers with an easily understandable overview and fundamental knowledge on implementing MHMRs.The MHMRs are actuated by rotating magnetic fields,achieving steering and rotation through magnetic torque,and converting rotation into forward motion through the helical structure.Magnetization methods for MHMRs are reviewed into three types:attaching magnets,magnetic coatings,and magnetic powder doping.Additionally,this review discusses the control methods for MHMRs,covering imaging techniques,path tracking control—including classical control algorithms and increasingly popular learning-based methods,and swarm control.Subsequently,a comprehensive survey is conducted on the biomedical applications of MHMRs in the treatment of vascular diseases,drug delivery,cell delivery,and their integration with catheters.We finally provide a perspective about future challenges in MHMR research,including enhancing functional design capabilities,developing swarm-assisted independent control mechanisms,refining in vivo imaging techniques,and ensuring robust biocompatibility for safe medical use.展开更多
A method is proposed to enhance the thermal stability of laser-powder bed fusion fabricated(L-PBFed)FeCoCrNi alloy by introducing Al element segregation through in-situ alloying.The introduced Al segregation exists in...A method is proposed to enhance the thermal stability of laser-powder bed fusion fabricated(L-PBFed)FeCoCrNi alloy by introducing Al element segregation through in-situ alloying.The introduced Al segregation exists in two forms of B2/BCC phases,one in banded shape within the FCC matrix and the other as particles at grain boundaries(GBs).Experimental characterization and molecular dynamics(MD)simulations were used to reveal the mechanism of the thermal stability of the grain boundary(GB)and dislocation in high-temperature treatment at 1000 and 1200℃.At high temperatures,short-range uphill diffusion occurs within the banded B2/BCC phase,forming the dispersed B2/BCC phase with higher(Al,Ni)content.This extends the stability of the banded B2/BCC phase and ensures high-strain hardening.Additionally,the long-range diffusion of Al atoms from the banded B2/BCC into the FCC matrix utilizes GBs as rapid channels at high temperatures.This process stabilizes GBs by reducing their cohesive energy and maintaining the nailing effect of the B2/BCC phase at GBs.Furthermore,after high-temperature treatment,dislocations within the FCC matrix exhibit a relatively high-density level,and many dislocations are generated within the B2/BCC regions subsequent to phase transition.This is attributed to the geometrically necessary dislocation(GND)generation caused by lattice distortion stemming from variations in Al content in the FCC matrix and lattice shrinkage induced by the phase transformation.As a result,the mechanical properties exhibit remarkable resistance to softening compared to traditional L-PBFed single FCC phase alloys.In terms of tensile properties at room temperature,after treatment at 1000℃/1 h,ultimate tensile strength(UTS)increased from 797 to 873 MPa.Even after 10 h at 1200℃,the UTS retained 86%of its original value.In terms of tensile properties at high temperature,compared to the L-PBFed FeCoCrNi alloy,the alloys prepared in this work exhibit an increase in yield strength(YS)by approximately 100 MPa under the same temperature conditions.This work can provide a new perspective for improving the thermal stability of L-PBFed alloys.展开更多
Perovskite materials have emerged as promising candidates for various optoelectronic applications owing to their remarkable optoelectronic properties and easy solution processing.Metal halide perovskites,as direct-ban...Perovskite materials have emerged as promising candidates for various optoelectronic applications owing to their remarkable optoelectronic properties and easy solution processing.Metal halide perovskites,as direct-bandgap semiconductors,show an excellent class of optical gain media,which makes them applicable to the development of low-threshold or even thresholdless lasers.This mini review explores recent advances in perovskite-based laser technology,which have led to chiral single-mode microlasers,low-threshold,external-cavity-free lasing devices at room temperature,and other innovative device architectures.Including self-assembled CsPbBr3 microwires that enable edge lasing.Realized continuous-wave(CW)pumped lasing by perovskite material pushes the research of electrically driven perovskite lasers.The capacity to regulate charge transport in halide perovskites further enhances their applicability in optoelectronic systems.The ongoing integration of perovskite materials with advanced photonic structures holds excellent potential for future innovations in laser technology and photovoltaics.We also highlight the transformative potential of perovskite materials in advancing the next generation of efficient and integrated optoelectronic devices.展开更多
The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexi...The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexible ball-end body-armor-like abrasive tool(BAAT)can effectively remove micro-convex peaks from the surfaces of brittle materials by employing a high tangential grinding force and a low normal grinding force,thereby achieving nano-level surface roughness and ultra-smooth mirror finishes.However,the surface contact me-chanism,pressure distribution pattern,and grinding force behavior between BAAT and workpiece remain in-adequately understood.This study examines the mechanism of liquid film formation and the distribution pattern of elastohydrodynamic pressure in high-shear and low-pressure grinding areas,drawing on the theories of elastohydrodynamic lubrication,non-Newtonian fluid dynamics,and material mechanics.A high-shear low-pressure grinding force model,which incorporates elastohydrodynamic liquid film thickness and abrasive grain size,was developed.The effects of the main grinding parameters(normal load,spindle rotational speed,and abrasive grain size)on the tangential grinding force were investigated through the processing of lithium niobate crystals using an intelligent precision-grinding system.The experimental results indicated that the relative error between the predicted and experimental values was 10.74%,thereby confirming the accuracy of the grinding force model.This study advances the understanding of elastohydrodynamic lubrication mechanisms in abrasive machining and provides a crucial theoretical foundation for the application of flexible ball-end BAAT.展开更多
Sodium superionic conductor(NASICON)-type materials are promising cathodes for sodium-ion batteries due to their stable multi-channel frameworks and exceptional ionic conductivity.Among them,Na_(3)V_2(PO_4)_(2)F_(3)(N...Sodium superionic conductor(NASICON)-type materials are promising cathodes for sodium-ion batteries due to their stable multi-channel frameworks and exceptional ionic conductivity.Among them,Na_(3)V_2(PO_4)_(2)F_(3)(NVPF)has attracted significant attention.However,the low electronic conductivity and phase impurities limit its sodium storage capability.Herein,we present a Fe and Mn dual-doped NVPF(FM-NVPF)cathode with improved phase purity,electronic conductivity,and electrochemical activities.Detailed ex-situ analyses and density functional theory calculations reveal that Fe and Mn dopants induce defect energy levels and modulate the electronic structure,resulting in a direct-to-indirect bandgap transition in NVPF,which in turn increases carrier concentration and lifetime,accelerates ionic/electronic transport,and improves structural stability.As a result,the FM-NVPF cathode delivers a high capacity of 126.6 mAh g^(-1)at 0.1 C(1 C=128 mAh g^(-1))and outstanding high-rate capability of 67.6 mAh g^(-1)at 50 C,corresponding to 1.2 min per charge.Furthermore,Na ion full cells assembled with the FM-NVPF cathodes and hard carbon anodes exhibit a high energy density of about 175 Wh kg^(-1)_(cathode+anode mass)and appealing cyclic stability.This work provides an efficient strategy for developing high-purity and high-performance NVPF cathode materials for advanced sodium-ion batteries.展开更多
A crystal plasticity model is developed to predict the cyclic plasticity during the low-cycle fatigue of GH4169 superalloy.Accumulated plastic slip and energy dissipation as fatigue indicator parameters(FIPs)are used ...A crystal plasticity model is developed to predict the cyclic plasticity during the low-cycle fatigue of GH4169 superalloy.Accumulated plastic slip and energy dissipation as fatigue indicator parameters(FIPs)are used to predict fatigue crack initiation and the fatigue life until failure.Results show that fatigue damage is most likely to initiate at triple points and grain boundaries where severe plastic slip and energy dissipation are present.The predicted fatigue life until failure is within the scatter band of factor 2 when compared with experimental data for the total strain amplitudes ranging from 0.8%to 2.4%.Microscopically,the adjacent grain arrangements and their interactions account for the stress concentration.In addition,different sets of grain orientations with the same total grain numbers of 150 were generated using the present model.Results show that different sets have significant influence on the distribution of stresses between each individual grain at the meso-scale,although little effect is found on the macroscopic length-scale.展开更多
Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward...Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward the top of melt pool tail. This resulted in a microstructure mainly composed of long and thin prior epitaxial β columnar grains (average width ^200μm). A periodic pattern in epitaxial growth of grains was observed, which was shown to depend upon laser traverse direction. Utilizing this, a novel means was proposed to determine accurately the fusion boundary of each deposited layer by inspection of the periodic wave patterns. As a result it was applied to investigate the influence of thermal cycling on microstructure evolution. Results showed that acicular martensite,α' phase, and a small amount of Widmanstatten, a laths, gradually converted to elongated acicular a and a large fraction of Widmanstatten a laths under layer-wise thermal cycling. Tensile tests showed that the yield strength, ultimate tensile strength and elongation of Ti-6Al-4V thin wall in the build direction were 9.1 %, 17.3% and 42% higher respectively than those typically observed in forged solids of the same alloy. It also showed the yield strength and ultimate tensile strength of the transverse tensile samples both were 13.3% higher than those from the build direction due to the strengthening effect of a large number of vertical β grain boundaries, but the elongation was 69.7% lower than that of the build direction due to the uneven grain deformation of β grains.展开更多
基金Research Institute for Smart Energy(CDB2)the grant from the Research Institute for Advanced Manufacturing(CD8Z)+4 种基金the grant from the Carbon Neutrality Funding Scheme(WZ2R)at The Hong Kong Polytechnic Universitysupport from the Hong Kong Polytechnic University(CD9B,CDBZ and WZ4Q)the National Natural Science Foundation of China(22205187)Shenzhen Municipal Science and Technology Innovation Commission(JCYJ20230807140402006)Start-up Foundation for Introducing Talent of NUIST and Natural Science Foundation of Jiangsu Province of China(BK20230426).
文摘Catalyst–support interaction plays a crucial role in improving the catalytic activity of oxygen evolution reaction(OER).Here we modulate the catalyst–support interaction in polyaniline-supported Ni_(3)Fe oxide(Ni_(3)Fe oxide/PANI)with a robust hetero-interface,which significantly improves oxygen evolution activities with an overpotential of 270 mV at 10 mA cm^(-2)and specific activity of 2.08 mA cm_(ECSA)^(-2)at overpotential of 300 mV,3.84-fold that of Ni_(3)Fe oxide.It is revealed that the catalyst–support interaction between Ni_(3)Fe oxide and PANI support enhances the Ni–O covalency via the interfacial Ni–N bond,thus promoting the charge and mass transfer on Ni_(3)Fe oxide.Considering the excellent activity and stability,rechargeable Zn-air batteries with optimum Ni_(3)Fe oxide/PANI are assembled,delivering a low charge voltage of 1.95 V to cycle for 400 h at 10 mA cm^(-2).The regulation of the effect of catalyst–support interaction on catalytic activity provides new possibilities for the future design of highly efficient OER catalysts.
基金mainly supported by the National Natural Science Foundation of China[No.52374312]the Science and Technology Innovation Program of Hunan Province[No.2024RC3026]+2 种基金the Natural Science Foundation of Hunan Province[No.2023JJ10076]the Research Institute for Advanced Manufacturing via the project No.1-CD9C,1-CDLR,Research Project of Zhuzhou Smelting Group Co.,Ltd.[ZYGFGH2307071500015]the High Performance Computing Center of Central South University。
文摘Metallic Zn anodes suffer from hydrogen evolution and dendritic deposition in aqueous electrolytes,resulting in low Coulombic efficiency and poor cyclic stability for aqueous Zn-ion batteries(AZIBs).Constructing stable solid electrolyte interphase(SEI)with strong affinity for Zn and exclusion of water corrosion of Zn metal anodes is a promising strategy to tackle these challenges.In this study,we develop a self-healing ZnO-based SEI film on the Zn electrode surface by employing an aspartame(APM)as a versatile electrolyte additive.The hydrophobic nature and strong Zn affinity of APM can facilitate the dynamic self-healing of ZnO-based SEI film during cyclic Zn plating/stripping process.Benefiting from the superior protection effect of self-healing ZnO-based SEI,the Zn║Cu cells possess an average coulombic efficiency more than 99.59%over 1,000 cycles even at a low current density of 1 m A cm^(-2)-1 m Ah cm^(-2).Furthermore,the Zn║NH_4~+-V_(2)O_5 full cells display a large specific capacity of 150 mAh g^(-1)and high cyclic stability with a capacity retention of 77.8%after 1,750 cycles.In addition,the Zn║Zn cell delivers high temperature adaptability at a wide-temperature range from-5 to 40℃ even under a high DOD of 85.2%.The enhanced capability and durability originate from the self-healing SEI formation enabled by multifunctional APM additives mediating both corrosion suppression and interfacial stabilization.This work presents an inspired and straightforward approach to promote a dendrite-free and widetemperature rechargeable AZIBs energy storage system.
基金supported by Guangdong Major Project of Basic and Applied Basic Research,China(No.2019B030302010)the Joint Research Scheme sponsored by the Research Grants Council of the Hong Kong Special Administrative Region,China and National Natural Science Foundation of China(Nos.N_PolyU523/20 and 52061160483)+4 种基金the National Natural Science Foundation of China(Nos.52104362,52071222,52471179,52471180 and 52001221)the National Key R&D Program of China(No.2022YFA1603800)the National Key Research and Development Program of China(No.2021YFA0716302)Guangdong Provincial Quantum Science Strategic Initiative(No.GDZX2301001)Guangdong Basic and Applied Basic Research,China(No.2020B1515130007).
文摘To fulfill the demands of applications under severe operational conditions,alloys should possess outstanding wear resistance at elevated temperatures.A Ti-Hf-Nb-V based refractory high entropy alloy(RHEA)was successfully produced using the directed energy deposition(DED)technique,which avoided the formation of fatal defects and showcased well-performed mechanical properties across a broad temperature spectrum.Strategic design of the oxidation sequence enabled the early formation of oxide nanolayers,which can form a polycrystalline oxide nanocoating under a complex stress condition to drastically reduce the wear rate from 2.69×10^(-4) mm^(3)·(N·m)^(−1) at room temperature to 6.90×10^(-7) mm^(3)·(N·m)^(−1) at 600℃.These results indicate that the application of additive manufacturing to fabricate RHEAs with superior wear resistance at high temperatures paves the way for the development of functional coatings designed to withstand extreme conditions.
基金financially supported by the Young Scientists Fund of National Natural Science Foundation of China(Grant No.52303106)Research Grants Council of Hong Kong SAR(16200720)+3 种基金Environment and Conservation Fund of Hong Kong SAR(Project No.21/2022)Research Institute of Sports Science and Technology(Project No.P0043535)Research Institute of Advanced Manufacturing(Project No.P0046125)the start-up fund for new recruits of Poly U(Project No.P0038855 and P0038858)。
文摘Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.
基金financially supported by the Research Grants Council of Hong Kong SAR(16200720)Environment and Conservation Fund of Hong Kong SAR(Project No.21/2022)+2 种基金Young Scientists Fund of National Natural Science Foundation of China(Grant No.52303106)Research Institute for Advanced Manufucturing(Project No.CD8R)the startup fund for new recruits of PolyU(Project Nos.P0038855 and P0038858)。
文摘Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Furthermore,downward salt ion transport is also desired to prevent salt accumulation.However,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal transport.Here,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal transport.The arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss.These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without degradation.Even in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal formation.This work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.
基金Funded by the Key Projects of Equipment Pre-research Foundation of the Ministry of Equipment Development of the Central Military Commission of China(No.6140922010201)the Key R&D Plan of Zhenjiang in 2018(No.GY2018021)。
文摘The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium matrix composites were prepared by discharge plasma sintering(SPS)and argon protective sintering(APS).The results show that the two processes have a negligible effect on the composition and hardness of the samples,but the hardness of the two samples is significantly improved by adding SiCp.The apparent porosity of SPS process is obviously smaller than that of APS process,whereas,the apparent porosity increases slightly with the addition of SiCp.The oxide layer thickness and mass gain of the samples obtained by SPS process are smaller than those obtained by APS process.The oxide thickness and mass gain of both processes are further reduced by adding SiCp.The SPS composites showed the best high temperature oxidation resistance.Therefore,TMCs with Si Cp by SPS can effectively improve the high-temperature oxidation behavior of the materials.
基金supported by the National Natural Science Foundation of China(Nos.51875329 and 51905322)China postdoctoral Science Foundation(No.2021T140420)+4 种基金Taishan Scholar Special Foundation of Shandong Province(No.tsqn201812064)Shandong Provincial Natural Science Foundation(No.ZR2017MEE050)Shandong Provincial Key Research and Development Project(No.2018GGX103008)Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(No.2019KJB030)Key Research and Development Project of Zibo City(No.2019ZBXC070).
文摘Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufacturing field.To improve the surface quality of the ground workpiece,a new high-shear and low-pressure grinding wheel,with high ratio of tangential grinding force to normal grinding force,was fabricated for the grinding of selective laser melting(SLM)manufactured Inconel718 alloy.The principle of high-shear and low-pressure grinding process was introduced in detail,which was quite different from the conventional grinding process.The fabrication process of the new grinding wheel was illustrated.A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained.The surface roughness of ground workpiece was reduced to 0.232μm from the initial value of 0.490μm under the optimal grinding conditions.It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM).The capability of the newly developed highshear and low-pressure grinding wheel was validated.
文摘Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition below a critical grain size.In this work,a facile laser surface remelting-based technique was employed and optimized to fabricate a∼600μm-thick heterogeneous gradient nanostructured layer on an austenitic Hadfield manganese steel,in which the average grain size is gradually decreased from∼200μm in the matrix to only∼8 nm in the nanocrystalline-amorphous core-shell topmost surface.Atomic-scale microstructural characterizations dissected the gradient refinement processes along the gradient direction,i.e.transiting from the dislocations activities and twinning in sub-region to three kinds of martensitic transformations,and finally a multi-phase nanocrystalline-amorphous core-shell structural surface.Mechanical tests(e.g.nanoindentation,bulk-specimen tensile,and micro-pillar compression)were conducted along the gradient direction.It confirms a tensile strength of∼1055 MPa and ductility of∼10.5%in the laser-processed specimen.Particularly,the core-shell structural surface maintains ultra-strong(tensile strength of∼1.6 GPa,micro-pillar compressive strength of∼4 GPa at a strain of∼8%,and nanoindentation hardness of∼7.7 GPa)to overcome the potential strengthening-softening transition.Such significant strengthening effects are ascribed to the strength-ductility synergetic effects-induced extra work hardening ability in gradient nanostructure and the well-maintained dislocation activities inside extremely refined nanograins in the multi-phase nanocrystalline-amorphous core-shell structural surface,which are evidenced by atomic-scale observations and theoretical analysis.This study provides a unique hetero-nanostructure through a facile laser-related technique for extraordinary mechanical performance.
基金Z.G.Yang acknowledges financial support from the National Key R&D program of China(grant No.2022YFB3705200)National Natural Science Foundation of China(grant No.52171008)+2 种基金H.Chen acknowledges financial support from the National Natural Science Foundation of China(grant No.51922054)Tsinghua University Initiative Scientific Research Program(No.20233080002)the Mobility Programme from the Sino-German Center(Grant No.M-0319).
文摘Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in UHSSs.In this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process.This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase.The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni enrichment.The hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)effect.As a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.
基金the Key Projects of Equipment Pre-research Foundation of the Ministry of Equipment Development of the Central Military Commission of China (No.6140922010201)the Key R&D Plan of Zhenjiang in 2018(No.GY2018021)。
文摘The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.
基金the financial support from National Natural Science Foundation of China(No.52171162)Research Grants Council of Hong Kong(Nos.15202824,15227121,C5002-24Y,C1017D21GF,and C1020D21GF)+4 种基金Shenzhen Science and Technology Program(No.JCYJ20210324142203009)the Research Institute for Advanced Manufacturing Fund(No.P0046108)PolyU Fund(Nos.P0044243 and P0043467)Guangdong Science and Technology Innovation Foundation(No.2023A1515240061)Open access funding provided by The Hong Kong Polytechnic University
文摘Interstitial alloying has emerged as a powerful strategy to tune microstructure and microproperties of high-entropy alloys(HEAs) due to the strong interaction of interstitials with constituent elements and crystal defects,which enables the development of advanced alloys with superior mechanical and functional properties. The paper reviews the latest progress in the atomic-scale understanding of the effects of various interstitials, including carbon, boron, nitrogen, oxygen, and hydrogen, on the microstructure, stability, mechanical properties, and deformation behavior of HEAs. Emphases are placed on the in-depth insights on the interaction of interstitials with constituent elements and crystal defects, such as vacancies,stacking faults, and grain boundaries. Key parameters for rapid prediction of intrinsic properties of HEAs are also discussed. Finally, we highlight some unsolved issues and provide perspectives for future research directions.
基金supported by the National Natural Science Foundation of China(Nos.52371014 and U22B20132)Shenzhen Science and Technology Program(No.JCYJ20230807091401004)+1 种基金Fundamental Research Funds for the Central Universities(No.20720230036)Guided Subject of Dean’s Fund(No.YZJJ-YDL-0004).
文摘The intrinsic properties of theγ′phase are well known to be of critical importance for the targeted control of the mechanical performance ofγ/γ′high entropy alloys(HEAs).In the present work,a composition tuning strategy is employed to modulate the thermal stability,elastic properties,and deformation mechanisms of theγ′phase in(FeCoNi)86Ti7Al7 HEAs using ab initio methods.Prior to tailoring the alloying elements,the temperature-dependent stability of theγ′phase is meticulously investigated by considering both enthalpic and entropic contributions.The findings reveal that the primary vibrational entropy can be effectively substituted by an empirical parameter(δ)to expedite the design of stable HEAs.Subsequently,based on the individual effects of elements on the order-disorder transformation temperatures(Tod)and practical considerations for high-temperature applications,eight substituting elements(Nb,Mo,Ta,W,V,Cr,Mn and Cu)are judiciously selected from the 3d,4d and 5d transition metal series.The results indicate that Nb and Ta are the most ideal substituting elements for theγ′phase,as they concurrently enhance the Tod,shear modulus,hardness,ductility,and antiphase boundary energy.These insights open a promising avenue for the innovative design of strong-yet-ductileγ/γ′HEAs.
基金the State Key Laboratory of Tribology in Advanced Equipment(Project code:SKLT2022C20)Postdoc Matching Fund Scheme of The Hong Kong Polytechnic University(Project code:1-W283)+3 种基金Research Institute of Advanced Manufacturing at The Hong Kong Polytechnic University(PolyU)(Project code:CD9E,CD8Y)PolyU Research and Inno-vation Office(Project code:BBR5)Departmental General Research Fund of the Department of Industrial and Systems Engineering of The Hong Kong Polytechnic University(Project code:G-UAKX)the funding support for the State Key Laboratories in Hong Kong from the Innovation and Technology Commission of the Govern-ment of the Hong Kong Special Administrative Region,China.
文摘In this study,we demonstrate the direct in-situ synthesis of NiTi alloys with tunable chemical com-position(Ni/Ti atomic ratio)and corresponding thermomechanical response.This synthesis is achieved by regulating the feeding speed ratio of pure Ni and Ti wires during the additive manufacturing pro-cess based on dual-wire-feed electron beam directed energy deposition(EB-DED)technology.Under ap-propriate process conditions,the resulting NiTi alloys exhibit a controllable evolution around the near-equiatomic composition and display a typical columnar grain morphology characteristic of additively manufactured NiTi alloys.With an increase in Ni content(shifting from Ti-rich to Ni-rich),the second phase particles present in the samples change from Ti-rich phase(Ti_(2) Ni)to Ni-rich phases(such as Ni4 Ti3 and Ni3 Ti_(2)).The phase transformation temperatures gradually decrease with increasing Ni content,and the predominant matrix phase transitions from martensite to austenite.The as-built NiTi alloy exhibits a typical tensile curve with a good tensile elongation of 11%,fabricated under suitable composition and microstructure conditions.This result surpasses values reported in current in-situ synthesized NiTi alloys through additive manufacturing methods.Moreover,it almost reaches the levels achieved by additively manufactured NiTi alloys using pre-alloyed raw materials.Furthermore,this study reports,for the first time in the field of in-situ synthesized NiTi alloys,a good tensile shape memory effect,achieving an im-pressive recovery rate of up to 70%under a tensile strain of 6%.This investigation provides a meaningful theoretical perspective and technical strategy for the integrated customization of NiTi alloy components in structure,composition,and function.This low-cost and high-efficiency approach is particularly attrac-tive for the preparation of functional graded,large-scale and disposable NiTi components.
基金the financial support from the Research Institute for Advanced Manufacturing(RIAM)of The Hong Kong Polytechnic University(project Nos.1-CD9F and 1-CDK3)the Research Grants Council(RGC)of Hong Kong(project Nos.25200424 and 15206223)+2 种基金the GuangDong Basic and Applied Basic Research Foundation(project No.2023A1515110709)the Startup fund(project No.1-BE9L)of the Hong Kong Polytechnic Universitysupported by grant from the Research Committee of the Hong Kong Polytechnic University under student account code RN5Y.
文摘Inspired by bacterial motility mechanisms,Magnetic Helical Miniature Robots(MHMRs)exhibit promising applications in biomedical fields due to their efficient locomotion and compatibility with biological tissues.In this review,we systematically survey the basics of MHMRs,from propulsion mechanism,magnetization and control methods to biomedical applications,aiming to provide readers with an easily understandable overview and fundamental knowledge on implementing MHMRs.The MHMRs are actuated by rotating magnetic fields,achieving steering and rotation through magnetic torque,and converting rotation into forward motion through the helical structure.Magnetization methods for MHMRs are reviewed into three types:attaching magnets,magnetic coatings,and magnetic powder doping.Additionally,this review discusses the control methods for MHMRs,covering imaging techniques,path tracking control—including classical control algorithms and increasingly popular learning-based methods,and swarm control.Subsequently,a comprehensive survey is conducted on the biomedical applications of MHMRs in the treatment of vascular diseases,drug delivery,cell delivery,and their integration with catheters.We finally provide a perspective about future challenges in MHMR research,including enhancing functional design capabilities,developing swarm-assisted independent control mechanisms,refining in vivo imaging techniques,and ensuring robust biocompatibility for safe medical use.
基金supported by the National Natural Science Foundation of China(No.52475371)the Key Research and Development Program of Shandong Province,China(No.2021ZLGX01)the Shandong Natural Science Foundation of China(No.ZR2020ZD05).
文摘A method is proposed to enhance the thermal stability of laser-powder bed fusion fabricated(L-PBFed)FeCoCrNi alloy by introducing Al element segregation through in-situ alloying.The introduced Al segregation exists in two forms of B2/BCC phases,one in banded shape within the FCC matrix and the other as particles at grain boundaries(GBs).Experimental characterization and molecular dynamics(MD)simulations were used to reveal the mechanism of the thermal stability of the grain boundary(GB)and dislocation in high-temperature treatment at 1000 and 1200℃.At high temperatures,short-range uphill diffusion occurs within the banded B2/BCC phase,forming the dispersed B2/BCC phase with higher(Al,Ni)content.This extends the stability of the banded B2/BCC phase and ensures high-strain hardening.Additionally,the long-range diffusion of Al atoms from the banded B2/BCC into the FCC matrix utilizes GBs as rapid channels at high temperatures.This process stabilizes GBs by reducing their cohesive energy and maintaining the nailing effect of the B2/BCC phase at GBs.Furthermore,after high-temperature treatment,dislocations within the FCC matrix exhibit a relatively high-density level,and many dislocations are generated within the B2/BCC regions subsequent to phase transition.This is attributed to the geometrically necessary dislocation(GND)generation caused by lattice distortion stemming from variations in Al content in the FCC matrix and lattice shrinkage induced by the phase transformation.As a result,the mechanical properties exhibit remarkable resistance to softening compared to traditional L-PBFed single FCC phase alloys.In terms of tensile properties at room temperature,after treatment at 1000℃/1 h,ultimate tensile strength(UTS)increased from 797 to 873 MPa.Even after 10 h at 1200℃,the UTS retained 86%of its original value.In terms of tensile properties at high temperature,compared to the L-PBFed FeCoCrNi alloy,the alloys prepared in this work exhibit an increase in yield strength(YS)by approximately 100 MPa under the same temperature conditions.This work can provide a new perspective for improving the thermal stability of L-PBFed alloys.
文摘Perovskite materials have emerged as promising candidates for various optoelectronic applications owing to their remarkable optoelectronic properties and easy solution processing.Metal halide perovskites,as direct-bandgap semiconductors,show an excellent class of optical gain media,which makes them applicable to the development of low-threshold or even thresholdless lasers.This mini review explores recent advances in perovskite-based laser technology,which have led to chiral single-mode microlasers,low-threshold,external-cavity-free lasing devices at room temperature,and other innovative device architectures.Including self-assembled CsPbBr3 microwires that enable edge lasing.Realized continuous-wave(CW)pumped lasing by perovskite material pushes the research of electrically driven perovskite lasers.The capacity to regulate charge transport in halide perovskites further enhances their applicability in optoelectronic systems.The ongoing integration of perovskite materials with advanced photonic structures holds excellent potential for future innovations in laser technology and photovoltaics.We also highlight the transformative potential of perovskite materials in advancing the next generation of efficient and integrated optoelectronic devices.
基金Supported by National Natural Science Foundation of China(Grant Nos.52575516,51875329)Taishan Scholar Special Foundation of Shandong Province(Grant Nos.tstp20240826,tsqn201812064)+2 种基金Shandong Provincial Natural Science Foundation(Grant No.ZR2023ME112)Key Research and Development Project of the Ningxia Hui Autonomous Region(Grant No.2024BEE02019)Innovation Capacity Improvement Programme for High-tech SMEs of Shandong Province(Grant Nos.2022TSGC1333,2022TSGC1261).
文摘The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexible ball-end body-armor-like abrasive tool(BAAT)can effectively remove micro-convex peaks from the surfaces of brittle materials by employing a high tangential grinding force and a low normal grinding force,thereby achieving nano-level surface roughness and ultra-smooth mirror finishes.However,the surface contact me-chanism,pressure distribution pattern,and grinding force behavior between BAAT and workpiece remain in-adequately understood.This study examines the mechanism of liquid film formation and the distribution pattern of elastohydrodynamic pressure in high-shear and low-pressure grinding areas,drawing on the theories of elastohydrodynamic lubrication,non-Newtonian fluid dynamics,and material mechanics.A high-shear low-pressure grinding force model,which incorporates elastohydrodynamic liquid film thickness and abrasive grain size,was developed.The effects of the main grinding parameters(normal load,spindle rotational speed,and abrasive grain size)on the tangential grinding force were investigated through the processing of lithium niobate crystals using an intelligent precision-grinding system.The experimental results indicated that the relative error between the predicted and experimental values was 10.74%,thereby confirming the accuracy of the grinding force model.This study advances the understanding of elastohydrodynamic lubrication mechanisms in abrasive machining and provides a crucial theoretical foundation for the application of flexible ball-end BAAT.
基金supported by the Innovation and Technology Fund-Innovation and Technology Support Program(ITF-ITSP)(Project No.ITS/126/21)Research Talent Hub for ITF project(RTH-ITF)(Project No.K-45-35-ZWC6)from the Innovation and Technology Commission of Hong Kong SARResearch Institute for Advanced Manufacturing(RIAM)at The Hong Kong Polytechnic University(Project No.1-CD9C)。
文摘Sodium superionic conductor(NASICON)-type materials are promising cathodes for sodium-ion batteries due to their stable multi-channel frameworks and exceptional ionic conductivity.Among them,Na_(3)V_2(PO_4)_(2)F_(3)(NVPF)has attracted significant attention.However,the low electronic conductivity and phase impurities limit its sodium storage capability.Herein,we present a Fe and Mn dual-doped NVPF(FM-NVPF)cathode with improved phase purity,electronic conductivity,and electrochemical activities.Detailed ex-situ analyses and density functional theory calculations reveal that Fe and Mn dopants induce defect energy levels and modulate the electronic structure,resulting in a direct-to-indirect bandgap transition in NVPF,which in turn increases carrier concentration and lifetime,accelerates ionic/electronic transport,and improves structural stability.As a result,the FM-NVPF cathode delivers a high capacity of 126.6 mAh g^(-1)at 0.1 C(1 C=128 mAh g^(-1))and outstanding high-rate capability of 67.6 mAh g^(-1)at 50 C,corresponding to 1.2 min per charge.Furthermore,Na ion full cells assembled with the FM-NVPF cathodes and hard carbon anodes exhibit a high energy density of about 175 Wh kg^(-1)_(cathode+anode mass)and appealing cyclic stability.This work provides an efficient strategy for developing high-purity and high-performance NVPF cathode materials for advanced sodium-ion batteries.
基金supported financially by the National Natural Sciene Foundation of China(Nos.51725503 and 51575183)111 Project+4 种基金Zhang XC is also grateful for the support by Shanghai Pujiang ProgramYoung Scholar of the Yangtze River Scholars ProgramShanghai Technology Innovation Program of SHEITC(No.CXY-2015-001)financial supports by Coventry University through the Early Career Researcher-Outgoing Mobility Awardthe East China University of Science and Technology through 111 Project to facilitate this international research collaboration.
文摘A crystal plasticity model is developed to predict the cyclic plasticity during the low-cycle fatigue of GH4169 superalloy.Accumulated plastic slip and energy dissipation as fatigue indicator parameters(FIPs)are used to predict fatigue crack initiation and the fatigue life until failure.Results show that fatigue damage is most likely to initiate at triple points and grain boundaries where severe plastic slip and energy dissipation are present.The predicted fatigue life until failure is within the scatter band of factor 2 when compared with experimental data for the total strain amplitudes ranging from 0.8%to 2.4%.Microscopically,the adjacent grain arrangements and their interactions account for the stress concentration.In addition,different sets of grain orientations with the same total grain numbers of 150 were generated using the present model.Results show that different sets have significant influence on the distribution of stresses between each individual grain at the meso-scale,although little effect is found on the macroscopic length-scale.
基金supported by the National Key Research and Development Program of China (No. 2018YFB1106302)the National Natural Science Foundation of China (Grant No. 51475380)the Aeronautical Science Foundation of China (Grant No. 2016ZE53)
文摘Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward the top of melt pool tail. This resulted in a microstructure mainly composed of long and thin prior epitaxial β columnar grains (average width ^200μm). A periodic pattern in epitaxial growth of grains was observed, which was shown to depend upon laser traverse direction. Utilizing this, a novel means was proposed to determine accurately the fusion boundary of each deposited layer by inspection of the periodic wave patterns. As a result it was applied to investigate the influence of thermal cycling on microstructure evolution. Results showed that acicular martensite,α' phase, and a small amount of Widmanstatten, a laths, gradually converted to elongated acicular a and a large fraction of Widmanstatten a laths under layer-wise thermal cycling. Tensile tests showed that the yield strength, ultimate tensile strength and elongation of Ti-6Al-4V thin wall in the build direction were 9.1 %, 17.3% and 42% higher respectively than those typically observed in forged solids of the same alloy. It also showed the yield strength and ultimate tensile strength of the transverse tensile samples both were 13.3% higher than those from the build direction due to the strengthening effect of a large number of vertical β grain boundaries, but the elongation was 69.7% lower than that of the build direction due to the uneven grain deformation of β grains.
