High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and co...High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and condensed matter physics due to their exceptional mechanical properties and unique high-entropy characteristic.Since the discovery of the first high-entropy superconductor in 2014,exploring their superconducting performance and advantages has progressively become a frontier in scientific research.The Ta-Nb-Hf-Zr-Ti system,in particular,exhibits remarkable mechanical robustness,outstanding radiation tolerance,and superconducting performance comparable to the binary NbTi alloy,positioning it as a promising candidate for advanced applications,such as high-field superconducting magnets,superconducting electric motors,and next-generation nuclear fusion reactors.This review systematically summarized global research progress on Ta-Nb-Hf-Zr-Ti-based superconductors,aiming to provide a comprehensive reference for advancing this burgeoning field.展开更多
Superconducting materials hold great potential in high field magnetic applications compared to traditional conductive materials.At present,practical superconducting materials include low-temperature superconductors su...Superconducting materials hold great potential in high field magnetic applications compared to traditional conductive materials.At present,practical superconducting materials include low-temperature superconductors such as NbTi and Nb3Sn,high-temperature superconductors such as Bi-2212,Bi-2223,YBCO,iron-based superconductors and MgB2.The development of low-temperature superconducting wires started earlier and has now entered the stage of industrialized production,showing obvious advantages in mechanical properties and cost under low temperature and middle-low magnetic field.However,due to the insufficient intrinsic superconducting performance,low-temperature superconductors are unable to exhibit excellent performance at high temperature or high fields.Further improvement of supercurrent carrying performance mainly depends on the enhancement of pinning ability.High-temperature superconductors have greater advantages in high temperature and high field,but many of them are still in the stage of further performance improvement.Many high-temperature superconductors are limited by the deficiency in their polycrystalline structure,and further optimization of intergranular connectivity is required.In addition,it is also necessary to further enhance their pinning ability.The numerous successful application instances of high-temperature superconducting wires and tapes also prove their tremendous potential in electric power applications.展开更多
The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was syn...The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was synthesized by high temperature solid-state method, taking the Mg element as a doping element and the spherical Ni<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> (OH)<sub>2</sub>, Li<sub>2</sub>CO<sub>3</sub> as raw materials. The effects of calcination temperature on the structure and properties of the products were investigated. The structure and morphology of cathode materials powder were analyzed by X-ray diffraction spectroscopy (XRD) and scanning electronmicroscopy (SEM). The electrochemical properties of the cathode materials were studied by charge-discharge test and cyclic properties test. The results show that LiNi<sub>0.4985</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> Mg<sub>0.0015</sub>O<sub>2</sub> cathode material prepared at calcination temperature 930°C has a good layered structure, and the compacted density of the electrode sheet is above 3.68 g/cm<sup>3</sup>. The discharge capacity retention rate is more than 97.5% after 100 cycles at a charge-discharge rate of 1C, displaying a good cyclic performance.展开更多
To guarantee the efficient and high-value reutilization of waste concrete from construction waste,the waste concrete was mechanically ground,and three degrees of fineness recycled concrete powder(RCP)were obtained by ...To guarantee the efficient and high-value reutilization of waste concrete from construction waste,the waste concrete was mechanically ground,and three degrees of fineness recycled concrete powder(RCP)were obtained by different grinding time.By analyzing the particle characteristics of RCP with different fineness,the filling-densification effect of cement-RCP cementitious material system was quantitatively investigated based on Andreasen,Fuller,and Aim-Goff models.In addition,the macroscopic mechanical properties of cement paste mixed with RCP were studied,and the influencing mechanisms of RCP on the microstructure of cement paste was revealed.Macroscopic research results show that the particle fineness of RCP after grinding is smaller than that of cement.When the RCP replaces 0%to 20%cement,the packing density based on the Aim-Goff model increases with the increase of RCP content,whereas the macro-mechanical properties first improve and then degrade with the increase of RCP content.Microscopic results show that at 5%RCP content,beneficial hydration products such as C-S-H and beneficial pore increase in cement-RCP paste;while at>15%content,beneficial products decrease and harmful substances such as Ca(OH)_(2)and harmful pore increases.These research findings suggest that the incorporation of RCP can make the cementitious system denser,and the appropriate RCP content can improve the macro-and microscopic properties of cement-based materials.展开更多
Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cann...Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cannot meet all clinical needs.In order to maximize therapeutic efficiency,herein,we fabricated a Tri-layer wound dressing,where the middle layer was fabricated via 3D-printing and composed of alginate,tragacanth and zinc oxide nanoparticles(ZnO NPs).Both upper and bottom layers were constructed using electrospinning technique;the upper layer was made of hydrophobic polycaprolactone to mimic epidermis,while the bottom layer consisted of Soluplus■ and insulin-like growth factor-1(IGF-1)to promote cell behavior.Swelling,water vapor permeability and tensile properties of the dressings were evaluated and the Tri-layer dressing exhibited impressive antibacterial activity and cell stimulation following by the release of ZnO NPs and IGF-1.Additionally,the Tri-layer dressing led to faster healing of full-thicknesswound in ratmodel compared to monolayer and Bilayer dressings.Overall,the evidence confirmed that the Trilayer wound dressing is extremely effective for full-thickness wound healing.展开更多
Tin-lead(Sn-Pb)halide perovskite single crystals combine narrow bandgaps,long carrier diffusion lengths,and low trap densities,positioning them as ideal candidates for near-infrared(NIR)optoelectronics.However,convent...Tin-lead(Sn-Pb)halide perovskite single crystals combine narrow bandgaps,long carrier diffusion lengths,and low trap densities,positioning them as ideal candidates for near-infrared(NIR)optoelectronics.However,conventional growth strategies rely on bulk crystallization at elevated temperatures,leading to uncontrolled nucleation,Sn^(2+)oxidation,and poor compatibility with planar integration.Here,we develop a coordination-engineered crystallization strategy that enables direct,lowtemperature growth of micrometer-thick Sn-Pb single-crystal thin films on device-compatible substrates.By modulating metal-solvent coordination strength using a low-donor number cosolvent system,we delineate a narrow processing window that stabilizes precursor speciation,lowers the nucleation barrier,and guides directional crystal growth under mild thermal conditions(<40℃).The resulting crystal films exhibit smooth morphology,high crystallinity,compositional uniformity,and ultralow trap densities(~3.98×10^(12)cm^(-3)).When integrated into NIR photodetectors,these films deliver high responsivity(0.51 A W^(-1)at 900 nm),specific detectivity up to 3.6×10^(12)Jones,fast response(~188μs),and>25,000 cycles of ambient operational stability.This approach establishes a scalable platform for redox-stable,low-temperature growth of Sn-Pb perovskite crystal films and expands the processing-structure-function landscape for next-generation infrared optoelectronics.展开更多
The electrolyte additive,lithium nitrate(LiNO_(3)),is widely recognized for suppressing dendritic lithium growth in anode-free lithium metal batteries,yet its stabilizing effect is transient,and the mechanistic origin...The electrolyte additive,lithium nitrate(LiNO_(3)),is widely recognized for suppressing dendritic lithium growth in anode-free lithium metal batteries,yet its stabilizing effect is transient,and the mechanistic origin of this limitation has remained unresolved.Here,we uncover the origin of this behavior through a comprehensive analysis driven by artifact/damage-free direct cryogenic transmission electron microscopy,which enabled one of the most chemically specific and morphologically intuitive visualizations to date of intact solid-electrolyte interphases(SEIs)and lithium growth.Contrary to conventional interpretations centered on nitrogen-rich or single-component SEIs,we reveal that LiNO_(3) rapidly generates lithium hydroxide(LiOH)and lithium oxide(Li_(2)O)rich interphases,whose complementary functions—ionic transport through LiOH and mechanical robustness from Li_(2)O—synergistically suppress whisker nucleation and favor compact,particle-like growth.Over the extended plating,however,depletion of these species in combination with crystallographically favored orientations drives the particle-towhisker transition,explaining why the effectiveness of LiNO_(3) is inherently limited.This direct mechanistic visualization resolves a long-standing ambiguity regarding the transient efficacy of LiNO_(3) and reframes its function from a nitrogen-driven mechanism to a synergistic dual oxygen-interphase framework.Beyond mechanistic clarification,these findings establish that continuous regeneration of LiOH and Li_(2)O is essential for stable lithium deposition,offering a design principle for the development of durable electrolytes in high-performance anode-free lithium metal batteries.展开更多
Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite i...Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite intensive research,the microscopic structure of the premelting layer and underlying molecular mechanisms remain poorly understood.In this work,we studied the temperature-and pressure-dependent structural disordering of crystalline Ih(0001)surface near the onset of premelting on the atomic scale by qPlus-based cryogenic atomic force microscopy.The linear correlation between the density of planar local structure(PLS)and the fraction of disordered surface region showed that the PLS mediated early-stage premelting by serving as a metastable seeding state.Notably,the associated surface disordering is cooperative,extending over an area of roughly~2 nm^(2) around a PLS.We further found a striking structural similarity between the kinetic-trapped regime below the surface crystallization temperature(T_(c))and the premelting-dominated regime above T_(c).As the deposition pressure increased,the characteristic temperature dependence was preserved,with only T_(c) shifting to higher values due to kinetic effects.Finally,we proposed a surface phase diagram for ice Ih(0001)based on our experimental observations.展开更多
To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with g...To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.展开更多
Cesium lead iodide perovskites offer promising stability and a bandgap near 1.7 eV,making them suitable as the top cell in tandem solar cells.However,the inorganic perovskite films suffer from a high defect density an...Cesium lead iodide perovskites offer promising stability and a bandgap near 1.7 eV,making them suitable as the top cell in tandem solar cells.However,the inorganic perovskite films suffer from a high defect density and substantial recombination losses,undermining their optoelectronic performances.Here,by activating the aromatic system,we develop 4-methoxybenzoylhydrazine(MeOBH)-modified CsPbI_(3) film with regulated crystallinity,suppressed non-radiative recombination,and improved interfacial energetic alignment.The resultant inorganic perovskite solar cells achieved a power conversion efficiency of 20.95%,along with enhanced phase stability owing to the strong coordination interaction between the lead cation and the hydrazide group.Encapsulated devices retain 90.4% of the initial performance after 624 h of maximum power point operation under the ISOS-L-1I protocol.展开更多
Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their ...Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.展开更多
The propagation of shock waves in a cellular bar is systematically studied in the framework of continuum solids by adopting two idealized material models, viz. the dynamic rigid, perfectly plastic, locking （D-R-PP-L...The propagation of shock waves in a cellular bar is systematically studied in the framework of continuum solids by adopting two idealized material models, viz. the dynamic rigid, perfectly plastic, locking （D-R-PP-L） model and the dynamic rigid, linear hardening plastic, locking （D-R-LHP-L） model, both considering the effects of strain-rate on the material properties. The shock wave speed relevant to these two models is derived. Consider the case of a bar made of one of such material with initial length L 0 and initial velocity v i impinging onto a rigid target. The variations of the stress, strain, particle velocity, specific internal energy across the shock wave and the cease distance of shock wave are all determined analytically. In particular the ＂energy conservation condition＂ and the ＂kinematic existence condition＂ as proposed by Tan et al. （2005） is re-examined, showing that the ＂energy conservation condition＂ and the consequent ＂critical velocity＂, i.e. the shock can only be generated and sustained in R-PP-L bars when the impact velocity is above this critical velocity, is incorrect. Instead, with elastic deformation, strain-hardening and strain-rate sensitivity of the cellular materials being considered, it is appropriate to redefine a first and a second critical impact velocity for the existence and propagation of shock waves in cellular solids. Starting from the basic relations for shock wave propagating in D-R-LHP-L cellular materials, a new method for inversely determining the dynamic stress-strain curve for cellular materials is proposed. By using e.g. a combination of Taylor bar and Hopkinson pressure bar impact experimental technique, the dynamic stress-strain curve of aluminum foam could bedetermined. Finally, it is demonstrated that this new formulation of shock theory in this one-dimensional stress state can be generalized to shocks in a one-dimensional strain state, i.e. for the case of plate impact on cellular materials, by simply making proper replacements of the elastic and plastic constants.展开更多
A two-dimensional(2 D)SnNb_(2)O_(6)/amino-functionalized graphene(En-RGO)nanocomposite with a representative 2 D-2 D architecture has been constructed by an easy self-assembly approach and firstly investigated as anod...A two-dimensional(2 D)SnNb_(2)O_(6)/amino-functionalized graphene(En-RGO)nanocomposite with a representative 2 D-2 D architecture has been constructed by an easy self-assembly approach and firstly investigated as anode materials for secondary sodium-ion batteries.The SnNb_(2)O_(6)nanosheets are evenly anchored with the aminofunctionalized graphene through electrostatic attractive interplay between the negatively charged SnNb_(2)O_(6)and positively charged En-RGO after modification.As a result,a remarkable reversible capacity of 300 mAh·g^(-1)was obtained at 50 mA·g^(-1),and significantly,the En-RGO electrode could also deliver ultra-long calendar life up to1900 cycles with a high reversible capacity of200 mAh·g^(-1)at current of 500 mA·g^(-1).Such excellent electrochemical characteristics can be mainly ascribed to its fast pseudo-capacitive energy storage mechanism,and the capacitive contribution can even reach up to 90%at1.2 mV·s^(-1).展开更多
How the wave propagation analysis plays a key role in the studies of dynamic response of materials at high strain rates is analyzed. For the wave propagation technique, the followings are important: the loading and un...How the wave propagation analysis plays a key role in the studies of dynamic response of materials at high strain rates is analyzed. For the wave propagation technique, the followings are important: the loading and unloading constitutive relation presumed, the positions of the sensors embedded, the interactions between loading waves and unloading waves. For the split Hopkinson pressure bar (SHPB) technique, the assumption of one-dimensional stress wave propagation and the assumption of stress uniformity along the specimen should be satisfied. When the larger diameter bars are employed, the wave dispersion effects should be considered, including the high frequency oscillations, non-uniform stress distribution across the bar section, increase of rise time, and amplitude attenuation. The stress uniformity along the specimen is influenced by the reflection times in specimen, the wave impedance ratio of the specimen and the bar, and the waveform.展开更多
Cellulose is a renewable biomass material and natural polymer which is abundantly available on Earth,and includes agricultural wastes,forestry residues,and woody materials.The excellent and smart characteristics of ce...Cellulose is a renewable biomass material and natural polymer which is abundantly available on Earth,and includes agricultural wastes,forestry residues,and woody materials.The excellent and smart characteristics of cellulose materials,such as lightweight,biocompatibility,biodegradability,high mechanical strength/stiffness and low thermal expansibility,have made cellulose a highpotential material for various industry applications.Cellulose has recently been discovered as a smart material in the electroactive polymers family which carries the name of cellulose-based electroactive paper(EAPap).The shear piezoelectricity in cellulose polymers is able to induce large displacement output,low actuation voltage,and low power consumption in the application of biomimetic sensors/actuators and electromechanical system.The present study provides an overview of biomass pretreatment from various lignocellulosic cellulose(LC)resources and nanocellulose production via TEMPO-mediated oxidation reaction,followed by the production of different types of EAPap versus its performance,and lastly the applications of EAPap in different areas and industries.Specifically,LC biomass consists mainly of cellulose having a small content of hemicelluloses and lignins which form a defensive inner structure against the degradation of plant cell wall.Thus,selective approaches are discussed to ensure proper extraction of cellulosic fibers from complex biomass for further minimization to nano-dimensions.In addition,a comprehensive review of the development of cellulose-based EAPap as well as fabrication,characterization,performance enhancement and applications of EAPap devices are discussed herein.展开更多
Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum ...Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.展开更多
Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling ...Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling performance.In this work,NbF_(5) was utilized to improve the cycling properties of the MgH_(2)-AlH_(3) composite.Cycling hydrogen desorption studies show that NbF_(5) significantly improves the cycling stability of MgH_(2)-AlH_(3).The MgH_(2)-AlH_(3)-NbF_(5) composite can release about 2.7 wt% of hydrogen at 300℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than100 cycles.In comparison,the hydrogen desorption capacity of the MgH_(2)-AlH_(3) composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles.Brunauer-Emmett-Teller(BET) surface area measurements show that the particle size of MgH_(2)-AlH_(3) composite decreases after cycling,which means pulverization of the composite.NbF_(5) can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.展开更多
Anisotropic Pr-Fe-B films with soft-magnetic layer （Fe） and/or antiferromagnetic layer （Mn, FeMn or MnO） were prepared by direct-current （DC） magnetron sputtering on Si （100） substrates heated at 650℃. The in...Anisotropic Pr-Fe-B films with soft-magnetic layer （Fe） and/or antiferromagnetic layer （Mn, FeMn or MnO） were prepared by direct-current （DC） magnetron sputtering on Si （100） substrates heated at 650℃. The influence of four types＇ different structures on the magnetic properties of Pr-Fe-B films was investigated. The phase and magnetic properties were characterized by means of X-ray diffraction （XRD） and superconducting quantum interference device （SQUID）. Addition of anti-ferromagnetic layer enhances both the coercivity and the remanence ratios of Pr-Fe-B films with suitable structures. The interface number increases and the antiferromagnetic-ferromagnetic exchange interaction is likely to become stronger, which affect the improvement of magnetic properties. To further understand the influence of structures with soft-magnetic Fe layer and/or antifer- romagnetic FeMn layer on the magnetic properties of Pr-Fe-B hard-magnetic films, the thickness of Pr-Fe-B layer was designed to decrease from 600 to 50 nm. The improvement of magnetic properties becomes obvious in Mo（50 nm）/Pr-Fe-B（25 nm）Mo（2 nm）FeMn（20 nm）Mo （2 nm）Pr-Fe-B（25 nm）/Mo（50 rim） film.展开更多
Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-b...Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-bone density make Mg-based alloys good candidates for fabricating surgical bioimplants for use in orthopedic and traumatology treatments.To this end,nowadays additive manufacturing(AM)along with three-dimensional(3D)printing represents a promising manufacturing technique as it allows for the integration of bioimplant design and manufacturing processes specific to given applications.Meanwhile,this technique also faces many new challenges associated with the properties of Mg-based alloys,including high chemical reactivity,potential for combustion,and low vaporization temperature.In this review article,various AM processes to fabricate biomedical implants from Mg-based alloys,along with their metallic microstructure,mechanical properties,biodegradability,biocompatibility,and antibacterial properties,as well as various post-AM treatments were critically reviewed.Also,the challenges and issues involved in AM processes from the perspectives of bioimplant design,properties,and applications were identified;the possibilities and potential scope of the Mg-based scaffolds/implants are discussed and highlighted.展开更多
Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challen...Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.展开更多
基金Northwest Institute of Nonferrous Metal Research Funding(YK2324)Key Research and Development Program of Shaanxi(2024GX-YBXM-403)National Natural Science Foundation of China(52277029)。
文摘High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and condensed matter physics due to their exceptional mechanical properties and unique high-entropy characteristic.Since the discovery of the first high-entropy superconductor in 2014,exploring their superconducting performance and advantages has progressively become a frontier in scientific research.The Ta-Nb-Hf-Zr-Ti system,in particular,exhibits remarkable mechanical robustness,outstanding radiation tolerance,and superconducting performance comparable to the binary NbTi alloy,positioning it as a promising candidate for advanced applications,such as high-field superconducting magnets,superconducting electric motors,and next-generation nuclear fusion reactors.This review systematically summarized global research progress on Ta-Nb-Hf-Zr-Ti-based superconductors,aiming to provide a comprehensive reference for advancing this burgeoning field.
基金supported by Xi'an Science and Technology Plan Project(Grant No.2024JH-CGKP-0073)。
文摘Superconducting materials hold great potential in high field magnetic applications compared to traditional conductive materials.At present,practical superconducting materials include low-temperature superconductors such as NbTi and Nb3Sn,high-temperature superconductors such as Bi-2212,Bi-2223,YBCO,iron-based superconductors and MgB2.The development of low-temperature superconducting wires started earlier and has now entered the stage of industrialized production,showing obvious advantages in mechanical properties and cost under low temperature and middle-low magnetic field.However,due to the insufficient intrinsic superconducting performance,low-temperature superconductors are unable to exhibit excellent performance at high temperature or high fields.Further improvement of supercurrent carrying performance mainly depends on the enhancement of pinning ability.High-temperature superconductors have greater advantages in high temperature and high field,but many of them are still in the stage of further performance improvement.Many high-temperature superconductors are limited by the deficiency in their polycrystalline structure,and further optimization of intergranular connectivity is required.In addition,it is also necessary to further enhance their pinning ability.The numerous successful application instances of high-temperature superconducting wires and tapes also prove their tremendous potential in electric power applications.
文摘The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was synthesized by high temperature solid-state method, taking the Mg element as a doping element and the spherical Ni<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> (OH)<sub>2</sub>, Li<sub>2</sub>CO<sub>3</sub> as raw materials. The effects of calcination temperature on the structure and properties of the products were investigated. The structure and morphology of cathode materials powder were analyzed by X-ray diffraction spectroscopy (XRD) and scanning electronmicroscopy (SEM). The electrochemical properties of the cathode materials were studied by charge-discharge test and cyclic properties test. The results show that LiNi<sub>0.4985</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> Mg<sub>0.0015</sub>O<sub>2</sub> cathode material prepared at calcination temperature 930°C has a good layered structure, and the compacted density of the electrode sheet is above 3.68 g/cm<sup>3</sup>. The discharge capacity retention rate is more than 97.5% after 100 cycles at a charge-discharge rate of 1C, displaying a good cyclic performance.
基金Funded by the National Natural Science Foundation of China Project(Nos.52108219 and U21A20150)the Lanzhou University of Technology Hongliu Outstanding Young Talent Program,China(No.04-062407)。
文摘To guarantee the efficient and high-value reutilization of waste concrete from construction waste,the waste concrete was mechanically ground,and three degrees of fineness recycled concrete powder(RCP)were obtained by different grinding time.By analyzing the particle characteristics of RCP with different fineness,the filling-densification effect of cement-RCP cementitious material system was quantitatively investigated based on Andreasen,Fuller,and Aim-Goff models.In addition,the macroscopic mechanical properties of cement paste mixed with RCP were studied,and the influencing mechanisms of RCP on the microstructure of cement paste was revealed.Macroscopic research results show that the particle fineness of RCP after grinding is smaller than that of cement.When the RCP replaces 0%to 20%cement,the packing density based on the Aim-Goff model increases with the increase of RCP content,whereas the macro-mechanical properties first improve and then degrade with the increase of RCP content.Microscopic results show that at 5%RCP content,beneficial hydration products such as C-S-H and beneficial pore increase in cement-RCP paste;while at>15%content,beneficial products decrease and harmful substances such as Ca(OH)_(2)and harmful pore increases.These research findings suggest that the incorporation of RCP can make the cementitious system denser,and the appropriate RCP content can improve the macro-and microscopic properties of cement-based materials.
基金support of Isfahan University of Medical Sciences(Project code No.#1401262).
文摘Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cannot meet all clinical needs.In order to maximize therapeutic efficiency,herein,we fabricated a Tri-layer wound dressing,where the middle layer was fabricated via 3D-printing and composed of alginate,tragacanth and zinc oxide nanoparticles(ZnO NPs).Both upper and bottom layers were constructed using electrospinning technique;the upper layer was made of hydrophobic polycaprolactone to mimic epidermis,while the bottom layer consisted of Soluplus■ and insulin-like growth factor-1(IGF-1)to promote cell behavior.Swelling,water vapor permeability and tensile properties of the dressings were evaluated and the Tri-layer dressing exhibited impressive antibacterial activity and cell stimulation following by the release of ZnO NPs and IGF-1.Additionally,the Tri-layer dressing led to faster healing of full-thicknesswound in ratmodel compared to monolayer and Bilayer dressings.Overall,the evidence confirmed that the Trilayer wound dressing is extremely effective for full-thickness wound healing.
基金support received from the National Research Foundation of Korea(NRF)through the Ministry of Science,ICT(Information and Communication Technology),under grant numbers RS-2023-00302646 and RS-2025-02316700.
文摘Tin-lead(Sn-Pb)halide perovskite single crystals combine narrow bandgaps,long carrier diffusion lengths,and low trap densities,positioning them as ideal candidates for near-infrared(NIR)optoelectronics.However,conventional growth strategies rely on bulk crystallization at elevated temperatures,leading to uncontrolled nucleation,Sn^(2+)oxidation,and poor compatibility with planar integration.Here,we develop a coordination-engineered crystallization strategy that enables direct,lowtemperature growth of micrometer-thick Sn-Pb single-crystal thin films on device-compatible substrates.By modulating metal-solvent coordination strength using a low-donor number cosolvent system,we delineate a narrow processing window that stabilizes precursor speciation,lowers the nucleation barrier,and guides directional crystal growth under mild thermal conditions(<40℃).The resulting crystal films exhibit smooth morphology,high crystallinity,compositional uniformity,and ultralow trap densities(~3.98×10^(12)cm^(-3)).When integrated into NIR photodetectors,these films deliver high responsivity(0.51 A W^(-1)at 900 nm),specific detectivity up to 3.6×10^(12)Jones,fast response(~188μs),and>25,000 cycles of ambient operational stability.This approach establishes a scalable platform for redox-stable,low-temperature growth of Sn-Pb perovskite crystal films and expands the processing-structure-function landscape for next-generation infrared optoelectronics.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00406724(50%)RS-2023-00222411,RS-2025-24533073)+2 种基金the Korea Basic Science Institute(National research Facilities and Equipment Center)grant funded by the Korea government(MOE)(RS-2024-00436346)the Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea government(MOTIE)(RS-2024-00417730,HRD Program for Industrial Innovation)the research fund of Hanyang University(HY-202100000003295)。
文摘The electrolyte additive,lithium nitrate(LiNO_(3)),is widely recognized for suppressing dendritic lithium growth in anode-free lithium metal batteries,yet its stabilizing effect is transient,and the mechanistic origin of this limitation has remained unresolved.Here,we uncover the origin of this behavior through a comprehensive analysis driven by artifact/damage-free direct cryogenic transmission electron microscopy,which enabled one of the most chemically specific and morphologically intuitive visualizations to date of intact solid-electrolyte interphases(SEIs)and lithium growth.Contrary to conventional interpretations centered on nitrogen-rich or single-component SEIs,we reveal that LiNO_(3) rapidly generates lithium hydroxide(LiOH)and lithium oxide(Li_(2)O)rich interphases,whose complementary functions—ionic transport through LiOH and mechanical robustness from Li_(2)O—synergistically suppress whisker nucleation and favor compact,particle-like growth.Over the extended plating,however,depletion of these species in combination with crystallographically favored orientations drives the particle-towhisker transition,explaining why the effectiveness of LiNO_(3) is inherently limited.This direct mechanistic visualization resolves a long-standing ambiguity regarding the transient efficacy of LiNO_(3) and reframes its function from a nitrogen-driven mechanism to a synergistic dual oxygen-interphase framework.Beyond mechanistic clarification,these findings establish that continuous regeneration of LiOH and Li_(2)O is essential for stable lithium deposition,offering a design principle for the development of durable electrolytes in high-performance anode-free lithium metal batteries.
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFA1400500 and 2025YFF1502400)the National Natural Science Foundation of China(Grant Nos.92361302,12250001,12535001,and U22A20260)+3 种基金the China Postdoctoral Science Foundation(Grant Nos.BX20230021,2023T160011,and 2024M760068)support from the National Program for Support of Top-notch Young professionalssupport from Beijing Outstanding Young Scientist Program(Grant No.JWZQ20240101002)the New Cornerstone Science Foundation through the New Cornerstone Investigator Program and the XPLORER PRIZE。
文摘Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite intensive research,the microscopic structure of the premelting layer and underlying molecular mechanisms remain poorly understood.In this work,we studied the temperature-and pressure-dependent structural disordering of crystalline Ih(0001)surface near the onset of premelting on the atomic scale by qPlus-based cryogenic atomic force microscopy.The linear correlation between the density of planar local structure(PLS)and the fraction of disordered surface region showed that the PLS mediated early-stage premelting by serving as a metastable seeding state.Notably,the associated surface disordering is cooperative,extending over an area of roughly~2 nm^(2) around a PLS.We further found a striking structural similarity between the kinetic-trapped regime below the surface crystallization temperature(T_(c))and the premelting-dominated regime above T_(c).As the deposition pressure increased,the characteristic temperature dependence was preserved,with only T_(c) shifting to higher values due to kinetic effects.Finally,we proposed a surface phase diagram for ice Ih(0001)based on our experimental observations.
基金Funded by the National Natural Science Foundation of China(Nos.5226804252468035)。
文摘To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.
基金financially supported by the National Ten Thousand Talent Program (H.C.)。
文摘Cesium lead iodide perovskites offer promising stability and a bandgap near 1.7 eV,making them suitable as the top cell in tandem solar cells.However,the inorganic perovskite films suffer from a high defect density and substantial recombination losses,undermining their optoelectronic performances.Here,by activating the aromatic system,we develop 4-methoxybenzoylhydrazine(MeOBH)-modified CsPbI_(3) film with regulated crystallinity,suppressed non-radiative recombination,and improved interfacial energetic alignment.The resultant inorganic perovskite solar cells achieved a power conversion efficiency of 20.95%,along with enhanced phase stability owing to the strong coordination interaction between the lead cation and the hydrazide group.Encapsulated devices retain 90.4% of the initial performance after 624 h of maximum power point operation under the ISOS-L-1I protocol.
基金supported by the National Natural Science Foundation of China (Grant Nos.12334001,52461160301,52322311,52427802,12222414)the National Key R&D Program of China (Grant Nos.2024YFA1208201,2021YFA1400500,2021YFA1400204)the Youth Innovation Promotion Association of the CAS (Grant Nos.Y2022003 and 2020009)。
文摘Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.
基金supported by the National Natural Science Foundation of China (11032001)the K.C.Wong Magna Fund in Ningbo University
文摘The propagation of shock waves in a cellular bar is systematically studied in the framework of continuum solids by adopting two idealized material models, viz. the dynamic rigid, perfectly plastic, locking （D-R-PP-L） model and the dynamic rigid, linear hardening plastic, locking （D-R-LHP-L） model, both considering the effects of strain-rate on the material properties. The shock wave speed relevant to these two models is derived. Consider the case of a bar made of one of such material with initial length L 0 and initial velocity v i impinging onto a rigid target. The variations of the stress, strain, particle velocity, specific internal energy across the shock wave and the cease distance of shock wave are all determined analytically. In particular the ＂energy conservation condition＂ and the ＂kinematic existence condition＂ as proposed by Tan et al. （2005） is re-examined, showing that the ＂energy conservation condition＂ and the consequent ＂critical velocity＂, i.e. the shock can only be generated and sustained in R-PP-L bars when the impact velocity is above this critical velocity, is incorrect. Instead, with elastic deformation, strain-hardening and strain-rate sensitivity of the cellular materials being considered, it is appropriate to redefine a first and a second critical impact velocity for the existence and propagation of shock waves in cellular solids. Starting from the basic relations for shock wave propagating in D-R-LHP-L cellular materials, a new method for inversely determining the dynamic stress-strain curve for cellular materials is proposed. By using e.g. a combination of Taylor bar and Hopkinson pressure bar impact experimental technique, the dynamic stress-strain curve of aluminum foam could bedetermined. Finally, it is demonstrated that this new formulation of shock theory in this one-dimensional stress state can be generalized to shocks in a one-dimensional strain state, i.e. for the case of plate impact on cellular materials, by simply making proper replacements of the elastic and plastic constants.
基金the National Natural Science Foundation of China(Nos.51871113 and21601071)the Natural Science Foundation of Jiangsu Province(No.BK20160211)the Key Research and Development Program of Xuzhou(No.KC17004)。
文摘A two-dimensional(2 D)SnNb_(2)O_(6)/amino-functionalized graphene(En-RGO)nanocomposite with a representative 2 D-2 D architecture has been constructed by an easy self-assembly approach and firstly investigated as anode materials for secondary sodium-ion batteries.The SnNb_(2)O_(6)nanosheets are evenly anchored with the aminofunctionalized graphene through electrostatic attractive interplay between the negatively charged SnNb_(2)O_(6)and positively charged En-RGO after modification.As a result,a remarkable reversible capacity of 300 mAh·g^(-1)was obtained at 50 mA·g^(-1),and significantly,the En-RGO electrode could also deliver ultra-long calendar life up to1900 cycles with a high reversible capacity of200 mAh·g^(-1)at current of 500 mA·g^(-1).Such excellent electrochemical characteristics can be mainly ascribed to its fast pseudo-capacitive energy storage mechanism,and the capacitive contribution can even reach up to 90%at1.2 mV·s^(-1).
文摘How the wave propagation analysis plays a key role in the studies of dynamic response of materials at high strain rates is analyzed. For the wave propagation technique, the followings are important: the loading and unloading constitutive relation presumed, the positions of the sensors embedded, the interactions between loading waves and unloading waves. For the split Hopkinson pressure bar (SHPB) technique, the assumption of one-dimensional stress wave propagation and the assumption of stress uniformity along the specimen should be satisfied. When the larger diameter bars are employed, the wave dispersion effects should be considered, including the high frequency oscillations, non-uniform stress distribution across the bar section, increase of rise time, and amplitude attenuation. The stress uniformity along the specimen is influenced by the reflection times in specimen, the wave impedance ratio of the specimen and the bar, and the waveform.
文摘Cellulose is a renewable biomass material and natural polymer which is abundantly available on Earth,and includes agricultural wastes,forestry residues,and woody materials.The excellent and smart characteristics of cellulose materials,such as lightweight,biocompatibility,biodegradability,high mechanical strength/stiffness and low thermal expansibility,have made cellulose a highpotential material for various industry applications.Cellulose has recently been discovered as a smart material in the electroactive polymers family which carries the name of cellulose-based electroactive paper(EAPap).The shear piezoelectricity in cellulose polymers is able to induce large displacement output,low actuation voltage,and low power consumption in the application of biomimetic sensors/actuators and electromechanical system.The present study provides an overview of biomass pretreatment from various lignocellulosic cellulose(LC)resources and nanocellulose production via TEMPO-mediated oxidation reaction,followed by the production of different types of EAPap versus its performance,and lastly the applications of EAPap in different areas and industries.Specifically,LC biomass consists mainly of cellulose having a small content of hemicelluloses and lignins which form a defensive inner structure against the degradation of plant cell wall.Thus,selective approaches are discussed to ensure proper extraction of cellulosic fibers from complex biomass for further minimization to nano-dimensions.In addition,a comprehensive review of the development of cellulose-based EAPap as well as fabrication,characterization,performance enhancement and applications of EAPap devices are discussed herein.
基金financially supported by the Science and Technology Department of Guangxi Zhuang Autonomous (No.GuiKeAD21238022)the Natural Science Foundation of Guangxi Province (No.2019GXNSFBA185004)National Natural Science Foundation of China (Nos.52001079,51961005 and 52261038)。
文摘Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.
基金financially supported by the National Natural Science Foundation of China(Nos.51771171 and 51971199)the Natural Science Foundation of Guangxi Province(Nos.2019GXNSFBA185004 and 2018GXNSFAA281308)the Basic Ability Improvement Project for Young and Middle-Aged Teachers in Colleges and Universities in Guangxi(No.2019KY0021)。
文摘Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling performance.In this work,NbF_(5) was utilized to improve the cycling properties of the MgH_(2)-AlH_(3) composite.Cycling hydrogen desorption studies show that NbF_(5) significantly improves the cycling stability of MgH_(2)-AlH_(3).The MgH_(2)-AlH_(3)-NbF_(5) composite can release about 2.7 wt% of hydrogen at 300℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than100 cycles.In comparison,the hydrogen desorption capacity of the MgH_(2)-AlH_(3) composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles.Brunauer-Emmett-Teller(BET) surface area measurements show that the particle size of MgH_(2)-AlH_(3) composite decreases after cycling,which means pulverization of the composite.NbF_(5) can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.
基金financially supported by the National Key Basic Research Program of China (No. 2010CB934603)the National Nature Science Foundation of China (Nos. 50931006 and 50971123)
文摘Anisotropic Pr-Fe-B films with soft-magnetic layer （Fe） and/or antiferromagnetic layer （Mn, FeMn or MnO） were prepared by direct-current （DC） magnetron sputtering on Si （100） substrates heated at 650℃. The influence of four types＇ different structures on the magnetic properties of Pr-Fe-B films was investigated. The phase and magnetic properties were characterized by means of X-ray diffraction （XRD） and superconducting quantum interference device （SQUID）. Addition of anti-ferromagnetic layer enhances both the coercivity and the remanence ratios of Pr-Fe-B films with suitable structures. The interface number increases and the antiferromagnetic-ferromagnetic exchange interaction is likely to become stronger, which affect the improvement of magnetic properties. To further understand the influence of structures with soft-magnetic Fe layer and/or antifer- romagnetic FeMn layer on the magnetic properties of Pr-Fe-B hard-magnetic films, the thickness of Pr-Fe-B layer was designed to decrease from 600 to 50 nm. The improvement of magnetic properties becomes obvious in Mo（50 nm）/Pr-Fe-B（25 nm）Mo（2 nm）FeMn（20 nm）Mo （2 nm）Pr-Fe-B（25 nm）/Mo（50 rim） film.
文摘Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-bone density make Mg-based alloys good candidates for fabricating surgical bioimplants for use in orthopedic and traumatology treatments.To this end,nowadays additive manufacturing(AM)along with three-dimensional(3D)printing represents a promising manufacturing technique as it allows for the integration of bioimplant design and manufacturing processes specific to given applications.Meanwhile,this technique also faces many new challenges associated with the properties of Mg-based alloys,including high chemical reactivity,potential for combustion,and low vaporization temperature.In this review article,various AM processes to fabricate biomedical implants from Mg-based alloys,along with their metallic microstructure,mechanical properties,biodegradability,biocompatibility,and antibacterial properties,as well as various post-AM treatments were critically reviewed.Also,the challenges and issues involved in AM processes from the perspectives of bioimplant design,properties,and applications were identified;the possibilities and potential scope of the Mg-based scaffolds/implants are discussed and highlighted.
基金supports of the National Key R&D Program of China(Project No.2017YFA0204403)Hong Kong Themebased Research Scheme Ref.(T13-402/17-N).
文摘Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.
