Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the n...Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.展开更多
There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capac...There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capacities.So that the community has started to explore alternative battery chemistries.As a promising multivalent battery type,rechargeable magnesium batteries(RMBs)have attracted increasing attention because of high safety,high volumetric energy density,and low cost thanks to abundant resource of Mg.However,the development of high-performance anodes is still hampered by formation of passivating layers on the Mg surface.Additionally,dendrites can also grow under certain conditions with pure Mg anodes,which requires further studies for reliable operation window and substitutes.Therefore,this review specifically aims to provide an overview on the often overlooked yet very important anode materials of RMBs,with the hope to inspire more attention and research efforts for the achievement of over-all better performance of future RMBs.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.展开更多
Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introductio...Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introduction.Cardiovascular diseases are the world’s leading cause of death.An especially debilitating heart disease is congestive heart failure.Among the possible therapies,heart transplantation and mechanical circulatory assistance are the main treatments for its severe form at a more advanced stage.The development of biomaterials for ventricular assist devices is still being carried out.Although polished titanium is currently employed in several devices,its performance could be improved by enhancing the bioactivity of its surface.Methods.Aiming to improve the titanium without using coatings that can be detached,this work presents the formation of laser-induced periodic surface structures with a topology suitable for cell adhesion and neointimal tissue formation.The surface was modified by femtosecond laser ablation and cell adhesion was evaluated in vitro by using fibroblast cells.Results.The results indicate the formation of the desired topology,since the cells showed the appropriate adhesion compared to the control group.Scanning electron microscopy showed several positive characteristics in the cells shape and their surface distribution.The in vitro results obtained with different topologies point that the proposed LIPSS would provide enhanced cell adhesion and proliferation.Conclusion.The laser processes studied can create new interactions in biomaterials already known and improve the performance of biomaterials for use in ventricular assist devices.展开更多
Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing o...Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.展开更多
A combined model to predict austenite grains growth of titanium micro-alloyed as-cast steel during reheating process was established.The model invoIves the behaviors of austenite grains growth in continuous heating pr...A combined model to predict austenite grains growth of titanium micro-alloyed as-cast steel during reheating process was established.The model invoIves the behaviors of austenite grains growth in continuous heating process and isothermal soaking process,and the variation of boundary pinning efficiency caused by the dissolution and coarsening kinetics of sec on d-phase particles was also con sidered into the model.Furthermore,the experimental verificatio ns were performed to examine the prediction power of the model.The results revealed that the mean austenite grains size increased with the increase in reheating temperature and soaking time,and the coarsening temperature of austenite grains growth was 1423 K under the current titanium content.In addition,the reliability of the predicted results in continuous heating process was validated by continuous heating experimenls.Moreover,an optimal regression expression of austenite grains growth in isothermal soaking process was obtained based on the experimental results.The compared results indicated that the combined model in conjunction with precipitates dissolution and coarsening kinetics had good reliability and accuracy to predict the austenite grains growth of titanium micro-alloyed casting steel during reheating process.展开更多
Combined theoretical and experimental efforts are put forward to study the critical factors influencing deformation mode transitions in face-centered cubic materials.We revisit the empirical relationship between the s...Combined theoretical and experimental efforts are put forward to study the critical factors influencing deformation mode transitions in face-centered cubic materials.We revisit the empirical relationship between the stacking fault energy(SFE)and the prevalent deformation mechanism.With ab initio calculated SFE,we establish the critical boundaries between various deformation modes in the model Cr-Co-Ni solid solution alloys.Satisfying agreement between theoretical predictions and experimental observations are reached.Our findings shield light on applying quantum mechanical calculations in designing transformation-induced plasticity and twinning-induced plasticity mechanisms for achieving advanced mechanical properties.展开更多
High entropy alloys(HEAs)based on transition metals display rich magnetic characteristics,however attempts on their application in energy efficient technologies remain scarce.Here,we explore the magnetocaloric applica...High entropy alloys(HEAs)based on transition metals display rich magnetic characteristics,however attempts on their application in energy efficient technologies remain scarce.Here,we explore the magnetocaloric application for a series of Mn_(x)Cr_(0.3)Fe_(0.5)Co_(0.2)Ni_(0.5)Al_(0.3)(0.8<x<1.1)HEAs by integrated theoretical and experimental methods.Both theory and experiment indicate the designed HEAs have the Curie temperature close to room temperature and is tunable with Mn concentration.A non-monotonic evolution is observed for both the entropy change and the relative cooling power with changing Mn concentration.The underlying atomic mechanism is found to primarily emerge from the complex impact of Mn on magnetism.Advanced magnetocaloric properties can be achieved by tuning Mn concentration in combination with controlling structural phase stability for the designed HEAs.展开更多
Solid solution strengthening(SSS)is one kind of strengthening mechanisms and plays an important role in alloy design,in particular for single-phase alloys including high-entropy alloys(HEAs).The classical Labusch–Nab...Solid solution strengthening(SSS)is one kind of strengthening mechanisms and plays an important role in alloy design,in particular for single-phase alloys including high-entropy alloys(HEAs).The classical Labusch–Nabarro model and its expansions are most widely applicable to treating SSS of solid solution alloys including both conventional alloys(CAs)and HEAs.In this study,the SSS effects in a series of Febased CAs and HEAs are investigated by using the classical Labusch–Nabarro model and its expansions.The size misfit and shear modulus misfit parameters are derived from first-principles calculations.Based on available experimental data in combination with empirical SSS model,we propose fitting constants(i.e.,the ratio between experimental hardness and predicted SSS effect)for these two families of alloys.The predicted host/alloy family-dependent fitting constants can be used to estimate the hardness of these SSS alloys.General agreement between predicted and measured hardness values is satisfactory for both CAs and HEAs,implying that the proposed approach is reliable and successful.展开更多
In order to efficiently explore the nearly infinite composition space in multicomponent solid solution alloys for reaching higher mechanical performance,it is important to establish predictive design strategies using ...In order to efficiently explore the nearly infinite composition space in multicomponent solid solution alloys for reaching higher mechanical performance,it is important to establish predictive design strategies using computation-aided methods.Here,using ab initio calculations we systematically study the effects of magnetism and chemical composition on the generalized stacking fault energy surface(γ-surface) of Cr-Co-Ni medium entropy alloys and show that both chemistry and the coupled magnetic state strongly affect the γ-surface,consequently,the primary deformation modes.The relations among various stable and unstable stacking fault energies are revealed and discussed.The present findings are useful for studying the deformation behaviors of Cr-Co-Ni alloys and facilitate a density functional theory based design of transformation-induced plasticity and twinning-induced plasticity mechanisms in Cr-Co-Ni alloys.展开更多
Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the a...Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the addition of Mo on microstructure and mechanical properties of the Mo-free parent alloy is lacking.In this work,we consider five(Co_(37.7)Cr_(24.4)Ni_(37.9))_(100-x)Mo_(x)(x=0,0.7,2.0,3.2,and 6.2)alloys,and reveal that yield/tensile strength and ductility are continuously increased for these alloys with increasing Mo content while a single-phase face-centered cubic structure remains unchanged.It is found that strong solid solution strengthening(SSS)is a main domain to the improved yield strength,whereas grain boundaries are found to soften by the Mo addition.The first-principles calculations demonstrate that a severe local lattice distortion contributes to the enhanced SSS,and the grain boundary softening effect is mostly associated with the decreased shear modulus.Both first-principles calculations and scanning transmission electron microscopy observations reveal that the stacking fault energy(SFE)reduces by the Mo addition.The calculated SFE value decreases from 0.4 mJ/m^(2) to-11.8 mJ/m^(2) at 0 K as Mo content increases from 0 at.%to 6.2 at.%,and experimentally measured values of SFE at room temperature for both samples are about 18 mJ/m^(2) and 9 mJ/m^(2),respectively.The reduction of SFE promoted the generation of stacking faults and deformation twins,which sustain a high strain hardening rate,thus postponing necking instability and enhancing tensile strength and elongation.展开更多
We design high entropy alloys(HEAs) with different induction elements(Si/Al/Sn).In order to keep the crystal structure invariant and to investigate how the increment in saturation magnetization(Ms)is caused only by th...We design high entropy alloys(HEAs) with different induction elements(Si/Al/Sn).In order to keep the crystal structure invariant and to investigate how the increment in saturation magnetization(Ms)is caused only by the change of electron spin state,each set of HEAs contains a different amount of Mn.Synergistic effects among induction elements that induce the magnetic transformation of Mn from anti-ferromagnetism to ferromagnetism are found.Ms of added Mn reduces when a particular induction element(Si_(0.4)/Al_(0.4)/Sn_(0.4)) exists,while a larger increment of Ms appears when two induction elements coexist,Si_(0.4)Al_(0.4)(25.79 emu/g) and Sn_(0.4)Al_(0.4)(15.43 emu/g).This is reflected in the microcosmic magnetic structure for the emergence of closed domains due to large demagnetization energy,which is confirmed by the Lorentz transmission electron microscope(LTEM) data.The calculated magnetic moments and the exchange integral constants from density functional theory based on the Exact Muffin-Tin Orbits fo rmalism reveal that the magnetic state and the strength of fe rromagnetic and anti-ferromagnetic coupling determine the variation of Ms in different chemical environments.The difference in energy levels of coexisting multiple induction elements also leads to a larger increment of Ms,Si_(0.4)Al_(0.4)Sn_(0.4)(29.78 emu/g),and Si_(0.4)Al_(0.4)Ge_(0.4)Sn_(0.4)(31.00 emu/g).展开更多
This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorpho...This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.展开更多
Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or...Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 nm.The raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical telescopes.The shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer scanner.The deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference pattern.The DLIP spot has a line-like interference pattern with about 15μm spatial period.Laser fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 mJ.Furthermore,an in-house built roll-to-roll machine was developed.Using this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be processed.Subsequently to current collector structuring coating of composite electrode material took place.In case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was achieved.The rate capability was increased up to 100%compared to reference material.At C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.展开更多
A planar honeycomb monolayer of siligraphene （SIC7） could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van de...A planar honeycomb monolayer of siligraphene （SIC7） could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van der Waals- induced first principles calculations based on density functional theory （DFT）, we have explored the structural, electronic, and hydrogen （H2） storage characteristics of SiC7 sheets decorated with various light metals. The binding energies of lithium （Li）, sodium （Na）, potassium （K）, magnesium （Mg）, calcium （Ca）, scandium （Sc）, and titanium （Ti） dopants on a SiC7 monolayer were studied at various doping concentrations, and found to be strong enough to counteract the metal clustering effect. We further verified the stabilities of the metallized SiC7 sheets at room temperature using ab initio molecular dynamics （MD） simulations. Bader charge analysis revealed that upon adsorption, due to the difference in electronegativity, all the metal adatorns donated a fraction of their electronic charges to the SiC7 sheet. Each partially charged metal center on the SiC7 sheets could bind a maximum of 4 to 5 H2 molecules. A high H2 gravimetric density was achieved for several dopants at a doping concentration of 12.50%. The H2 binding energies were found to fall within the ideal range of 0.2-0.6 eV. Based on these findings, we propose that metal-doped SiC7 sheets can operate as efficient H2 storage media under ambient conditions.展开更多
In this study,we perform a numerical investigation of a steady laminar stagnation flow flame stabilized at a wall with the consideration of heat transport,focusing on a lean hydrogen/air mixture with a fuel/air equiva...In this study,we perform a numerical investigation of a steady laminar stagnation flow flame stabilized at a wall with the consideration of heat transport,focusing on a lean hydrogen/air mixture with a fuel/air equivalence ratio 0.6.We discuss the NO emissions and their formation rates under various conditions,such as flow velocity and combustion pressure.It is found that the predominant reaction pathway for NO formation involves NNH radicals,though this changes near the wall surface.Beyond examining the wall's influence on flame structures,the present work focuses on the impact of combustion process on materials.Specifically,the accumulation of atomic hydrogen at the wall surface is explored,which is significant for the consequent modeling of potential hydrogen embrittlement.Additionally,the growth rate of oxide layers on the material surface increases significantly if the combustion pressure and consequently the combustion temperatures are enhanced.These investigations offer valuable insights into how combustion processes affect material,which is useful for designing engineering components under high-temperature environments.展开更多
Subsoiling has been widely used all over the world as an important operation method of no-tillage farming.For energy-saving and life-extension,the tillage resistance and wear-corrosion of subsoilers have attracted wid...Subsoiling has been widely used all over the world as an important operation method of no-tillage farming.For energy-saving and life-extension,the tillage resistance and wear-corrosion of subsoilers have attracted wide attention.In this study,the tillage resistance,soil disturbance,wear and corrosion of subsoiler with S-T-SK-2#biomimetic structures(S means subsoiler;T means tine;SK means shank;2#,h/s=0.57,h=5 mm andα=45°.)and self-healing coating under two seasons,two locations with different soil properties(black loam and clay soil)and subsoiling speeds(2 km/h and 3.6 km/h)were investigated.The soil moisture content and compactness affected the tillage resistance and wear-corrosion.The tillage resistance and degree of corrosion on all subsoilers were much larger in clay soil than that in black loam soil.Compared with S-T-SK-2#,the tillage reduction rate of C-S-T-SK-2#(S-T-SK-2#with self-healing coating)was up to 14.32%in clay soil under the speed of 2 km/h.The significance tests of regression equation results showed that subsoiler type and soil properties had a significant impact on soil disturbance coefficient,swelling of total soil layer,bulkiness of the plough pan.It is of a guiding significance for the analysis of soil disturbance.Synergism mechanism of subsoiler coupling with biomimetic structures and self-healing coating was analyzed in following.It depicted the guiding effect of biomimetic structure and the shield function of self-healing coating,resulting in anticorrosion and wear resistance of subsoiler.展开更多
Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced sha...Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys （e.g., the martensitic transformation temperature TM） sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C＇ is a better predictor of the composition dependent TM than the number of valence electrons per atom （e/a） since the general TM-C＇ correlation works for some of the alloys for which the TM-ela correlation fails, although there exist several cases for which both the general TM-C＇ and TM-ela correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated （5M） structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the marten- sites is examined by comparing their total energies. The non-modulated martensite β＇″ with the tetragonality of the unit cell c/a〉1 is shown to be globally stable whereas the 5M martensite with c/a〈1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reason- able agreement with experimental findings.展开更多
基金The research to anode material development received funding from the German Research Foundation(DFG,project No.392322200)the development of cathode materials and upscaling strategies was funded by the Federal Ministry of Education and Research(Project NextGen-3DBat,03XP0198F).
文摘Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.
基金the German Research Foundation DFG project(LI 2839/1-1)National Natural Science Foundation of China(51971044)MF acknowledges funding from EU research and innovation framework programme via ttE-MAGIC,project(ID:824066)。
文摘There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capacities.So that the community has started to explore alternative battery chemistries.As a promising multivalent battery type,rechargeable magnesium batteries(RMBs)have attracted increasing attention because of high safety,high volumetric energy density,and low cost thanks to abundant resource of Mg.However,the development of high-performance anodes is still hampered by formation of passivating layers on the Mg surface.Additionally,dendrites can also grow under certain conditions with pure Mg anodes,which requires further studies for reliable operation window and substitutes.Therefore,this review specifically aims to provide an overview on the often overlooked yet very important anode materials of RMBs,with the hope to inspire more attention and research efforts for the achievement of over-all better performance of future RMBs.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.
文摘Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introduction.Cardiovascular diseases are the world’s leading cause of death.An especially debilitating heart disease is congestive heart failure.Among the possible therapies,heart transplantation and mechanical circulatory assistance are the main treatments for its severe form at a more advanced stage.The development of biomaterials for ventricular assist devices is still being carried out.Although polished titanium is currently employed in several devices,its performance could be improved by enhancing the bioactivity of its surface.Methods.Aiming to improve the titanium without using coatings that can be detached,this work presents the formation of laser-induced periodic surface structures with a topology suitable for cell adhesion and neointimal tissue formation.The surface was modified by femtosecond laser ablation and cell adhesion was evaluated in vitro by using fibroblast cells.Results.The results indicate the formation of the desired topology,since the cells showed the appropriate adhesion compared to the control group.Scanning electron microscopy showed several positive characteristics in the cells shape and their surface distribution.The in vitro results obtained with different topologies point that the proposed LIPSS would provide enhanced cell adhesion and proliferation.Conclusion.The laser processes studied can create new interactions in biomaterials already known and improve the performance of biomaterials for use in ventricular assist devices.
基金financially supported by the National Natural Science Foundation of China (No. 52001120)the Fundamental Research Funds for the Central Universities (No. 531118010450)+10 种基金the Hundred Talent Program of Hunan Provincethe State Key Laboratory of Powder Metallurgy,Central South University,Changshathe State Key Laboratory of Advanced Metals and Materials(No. 2021-Z09)University of Science&Technology Beijing,Chinasupported by the National Natural Science Foundation of China (No. 51801060)supported by the Swedish Research Councilsupported by the National Science Foundation under Contract (No. DMR-1408722)sponsored by the Whiting School of EngineeringJohns Hopkins Universityfunded by the National Key Research and Development Program of China (No. 2016YFB0300801)the National NaturalScience Foundation of China (Nos. 51831004, 11427806, 51671082,51471067)。
文摘Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.
基金National Natural Science Foundation of China(Grant Nos.51504048,51874060,51874059 and 51611130062)The authors would like to acknowledge the members of Laboratory of Metallurgy and Materials,Chongqing University,for the support of this work.
文摘A combined model to predict austenite grains growth of titanium micro-alloyed as-cast steel during reheating process was established.The model invoIves the behaviors of austenite grains growth in continuous heating process and isothermal soaking process,and the variation of boundary pinning efficiency caused by the dissolution and coarsening kinetics of sec on d-phase particles was also con sidered into the model.Furthermore,the experimental verificatio ns were performed to examine the prediction power of the model.The results revealed that the mean austenite grains size increased with the increase in reheating temperature and soaking time,and the coarsening temperature of austenite grains growth was 1423 K under the current titanium content.In addition,the reliability of the predicted results in continuous heating process was validated by continuous heating experimenls.Moreover,an optimal regression expression of austenite grains growth in isothermal soaking process was obtained based on the experimental results.The compared results indicated that the combined model in conjunction with precipitates dissolution and coarsening kinetics had good reliability and accuracy to predict the austenite grains growth of titanium micro-alloyed casting steel during reheating process.
基金provided by the Major State Basic Research Development Program of China(2016YFB0701405)supported by the KTH-SJTU collaborative research and development seed grant+6 种基金the Swedish Research Councilthe Swedish Foundation for Strategic Researchthe China Scholarship Councilthe Swedish Foundation for International Cooperation in Research and Higher Educationthe Hungarian Scientific Research Fund(research project OTKA 128229)the Fundamental Research Funds for the Central Universities under grant No.N180204015partially funded by the Swedish Research Council through grant agreement no.2018–05973
文摘Combined theoretical and experimental efforts are put forward to study the critical factors influencing deformation mode transitions in face-centered cubic materials.We revisit the empirical relationship between the stacking fault energy(SFE)and the prevalent deformation mechanism.With ab initio calculated SFE,we establish the critical boundaries between various deformation modes in the model Cr-Co-Ni solid solution alloys.Satisfying agreement between theoretical predictions and experimental observations are reached.Our findings shield light on applying quantum mechanical calculations in designing transformation-induced plasticity and twinning-induced plasticity mechanisms for achieving advanced mechanical properties.
基金supported by the Swedish Research Council(2015-5335 and 2017-06474)the Swedish Foundation for Strategic Research (S14-0038 and SM16-0036)+3 种基金the Swedish Foundation for International Cooperation in Research and Higher Education(CH2015-6292)the Swedish Energy Agency,the Hungarian Scientific Research Fund (OTKA 128229)the Carl Tryggers Foundationsupport from the Swedish Energy Agency (Energimyndigheten),ST and UPP and e SSENCE
文摘High entropy alloys(HEAs)based on transition metals display rich magnetic characteristics,however attempts on their application in energy efficient technologies remain scarce.Here,we explore the magnetocaloric application for a series of Mn_(x)Cr_(0.3)Fe_(0.5)Co_(0.2)Ni_(0.5)Al_(0.3)(0.8<x<1.1)HEAs by integrated theoretical and experimental methods.Both theory and experiment indicate the designed HEAs have the Curie temperature close to room temperature and is tunable with Mn concentration.A non-monotonic evolution is observed for both the entropy change and the relative cooling power with changing Mn concentration.The underlying atomic mechanism is found to primarily emerge from the complex impact of Mn on magnetism.Advanced magnetocaloric properties can be achieved by tuning Mn concentration in combination with controlling structural phase stability for the designed HEAs.
基金The National Natural Science Foundation of China(No.51871175)Opening Project of Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research,College of Stomatology,Xi’an Jiaotong University(No.2021LHM-KFKT005)+2 种基金the Innovation Fund of Materials Research of the Chinese Academy of Engineering Physics(No.CX201909)Fund of Key Laboratory of Surface Physics and Chemistry(No.XKFZ201902)are acknowledged for financial supportthe financial support of the US AFOSR(No.FA9550-20-1-0015)。
文摘Solid solution strengthening(SSS)is one kind of strengthening mechanisms and plays an important role in alloy design,in particular for single-phase alloys including high-entropy alloys(HEAs).The classical Labusch–Nabarro model and its expansions are most widely applicable to treating SSS of solid solution alloys including both conventional alloys(CAs)and HEAs.In this study,the SSS effects in a series of Febased CAs and HEAs are investigated by using the classical Labusch–Nabarro model and its expansions.The size misfit and shear modulus misfit parameters are derived from first-principles calculations.Based on available experimental data in combination with empirical SSS model,we propose fitting constants(i.e.,the ratio between experimental hardness and predicted SSS effect)for these two families of alloys.The predicted host/alloy family-dependent fitting constants can be used to estimate the hardness of these SSS alloys.General agreement between predicted and measured hardness values is satisfactory for both CAs and HEAs,implying that the proposed approach is reliable and successful.
基金financially supported by the Major State Basic Research Development Program of China(No.2016YFB0701405)supported by the KTH-SJTU collaborative research and development seed grant in 2018,the Swedish Research Council(No.2019-04971)+2 种基金the Swedish Foundation for Strategic Research,the China Scholarship Council,the Swedish Energy Agency,the Hungarian Scientific Research Fund(No.research project OTKA 128229)the Fundamental Research Funds for the Central Universities(No.N180204015)The computation resource provided by the Swedish National Infrastructure for Computing(SNIC)at the National Supercomputer Centre in Linkoping,which is partially funded by the Swedish Research Council through grant agreement no.2018-05973。
文摘In order to efficiently explore the nearly infinite composition space in multicomponent solid solution alloys for reaching higher mechanical performance,it is important to establish predictive design strategies using computation-aided methods.Here,using ab initio calculations we systematically study the effects of magnetism and chemical composition on the generalized stacking fault energy surface(γ-surface) of Cr-Co-Ni medium entropy alloys and show that both chemistry and the coupled magnetic state strongly affect the γ-surface,consequently,the primary deformation modes.The relations among various stable and unstable stacking fault energies are revealed and discussed.The present findings are useful for studying the deformation behaviors of Cr-Co-Ni alloys and facilitate a density functional theory based design of transformation-induced plasticity and twinning-induced plasticity mechanisms in Cr-Co-Ni alloys.
基金financially supported by the Young Scientists Fund of the National Natural Science Foundation of China(No.52001120)the Hunan Provincial National Science Fund for Distin-guished Young Scholars(No.2022JJ10015)+2 种基金the State Key Labora-tory of Advanced Metals and Materials(No.2021-Z09)the Univer-sity of Science&Technology Beijing,China.X.Q.Li was supported by the Swedish Research Council(No.2020-03736)funded by the Swedish Research Council through grant agreement(No.2018-05973)。
文摘Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the addition of Mo on microstructure and mechanical properties of the Mo-free parent alloy is lacking.In this work,we consider five(Co_(37.7)Cr_(24.4)Ni_(37.9))_(100-x)Mo_(x)(x=0,0.7,2.0,3.2,and 6.2)alloys,and reveal that yield/tensile strength and ductility are continuously increased for these alloys with increasing Mo content while a single-phase face-centered cubic structure remains unchanged.It is found that strong solid solution strengthening(SSS)is a main domain to the improved yield strength,whereas grain boundaries are found to soften by the Mo addition.The first-principles calculations demonstrate that a severe local lattice distortion contributes to the enhanced SSS,and the grain boundary softening effect is mostly associated with the decreased shear modulus.Both first-principles calculations and scanning transmission electron microscopy observations reveal that the stacking fault energy(SFE)reduces by the Mo addition.The calculated SFE value decreases from 0.4 mJ/m^(2) to-11.8 mJ/m^(2) at 0 K as Mo content increases from 0 at.%to 6.2 at.%,and experimentally measured values of SFE at room temperature for both samples are about 18 mJ/m^(2) and 9 mJ/m^(2),respectively.The reduction of SFE promoted the generation of stacking faults and deformation twins,which sustain a high strain hardening rate,thus postponing necking instability and enhancing tensile strength and elongation.
基金supported financially by the Program for the National Key R&D Program of China (No.2017YFB0703103)the National Natural Science Foundation of China (Nos.51577021 and U1704253)+1 种基金the Fundamental Research Funds for the Central Universities (DUT17GF107)the Swedish Foundation for Strategic Research。
文摘We design high entropy alloys(HEAs) with different induction elements(Si/Al/Sn).In order to keep the crystal structure invariant and to investigate how the increment in saturation magnetization(Ms)is caused only by the change of electron spin state,each set of HEAs contains a different amount of Mn.Synergistic effects among induction elements that induce the magnetic transformation of Mn from anti-ferromagnetism to ferromagnetism are found.Ms of added Mn reduces when a particular induction element(Si_(0.4)/Al_(0.4)/Sn_(0.4)) exists,while a larger increment of Ms appears when two induction elements coexist,Si_(0.4)Al_(0.4)(25.79 emu/g) and Sn_(0.4)Al_(0.4)(15.43 emu/g).This is reflected in the microcosmic magnetic structure for the emergence of closed domains due to large demagnetization energy,which is confirmed by the Lorentz transmission electron microscope(LTEM) data.The calculated magnetic moments and the exchange integral constants from density functional theory based on the Exact Muffin-Tin Orbits fo rmalism reveal that the magnetic state and the strength of fe rromagnetic and anti-ferromagnetic coupling determine the variation of Ms in different chemical environments.The difference in energy levels of coexisting multiple induction elements also leads to a larger increment of Ms,Si_(0.4)Al_(0.4)Sn_(0.4)(29.78 emu/g),and Si_(0.4)Al_(0.4)Ge_(0.4)Sn_(0.4)(31.00 emu/g).
基金financially supported by the National Natural Science Foundation of China(No.51827801)the support by the Overseas Visiting Study Program of Harbin Institute of Technology。
文摘This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.
基金funded by the German Federal Ministry of Education and Research(BMBF),project NextGen-3DBat,Grant Number 03XP0198Fby the Fraunhofer Cluster of Excellence Advanced Photon Sources(CAPS)。
文摘Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 nm.The raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical telescopes.The shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer scanner.The deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference pattern.The DLIP spot has a line-like interference pattern with about 15μm spatial period.Laser fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 mJ.Furthermore,an in-house built roll-to-roll machine was developed.Using this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be processed.Subsequently to current collector structuring coating of composite electrode material took place.In case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was achieved.The rate capability was increased up to 100%compared to reference material.At C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.
文摘A planar honeycomb monolayer of siligraphene （SIC7） could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van der Waals- induced first principles calculations based on density functional theory （DFT）, we have explored the structural, electronic, and hydrogen （H2） storage characteristics of SiC7 sheets decorated with various light metals. The binding energies of lithium （Li）, sodium （Na）, potassium （K）, magnesium （Mg）, calcium （Ca）, scandium （Sc）, and titanium （Ti） dopants on a SiC7 monolayer were studied at various doping concentrations, and found to be strong enough to counteract the metal clustering effect. We further verified the stabilities of the metallized SiC7 sheets at room temperature using ab initio molecular dynamics （MD） simulations. Bader charge analysis revealed that upon adsorption, due to the difference in electronegativity, all the metal adatorns donated a fraction of their electronic charges to the SiC7 sheet. Each partially charged metal center on the SiC7 sheets could bind a maximum of 4 to 5 H2 molecules. A high H2 gravimetric density was achieved for several dopants at a doping concentration of 12.50%. The H2 binding energies were found to fall within the ideal range of 0.2-0.6 eV. Based on these findings, we propose that metal-doped SiC7 sheets can operate as efficient H2 storage media under ambient conditions.
基金financial support by the DFG (project H2MAT3D,project number 523879740 within the DFG-SPP 2419 HyCAM)the Deutsche Forschungsgemeinschaft (DFG),Germany for its support within Project TH881/38-1 (DADOREN)。
文摘In this study,we perform a numerical investigation of a steady laminar stagnation flow flame stabilized at a wall with the consideration of heat transport,focusing on a lean hydrogen/air mixture with a fuel/air equivalence ratio 0.6.We discuss the NO emissions and their formation rates under various conditions,such as flow velocity and combustion pressure.It is found that the predominant reaction pathway for NO formation involves NNH radicals,though this changes near the wall surface.Beyond examining the wall's influence on flame structures,the present work focuses on the impact of combustion process on materials.Specifically,the accumulation of atomic hydrogen at the wall surface is explored,which is significant for the consequent modeling of potential hydrogen embrittlement.Additionally,the growth rate of oxide layers on the material surface increases significantly if the combustion pressure and consequently the combustion temperatures are enhanced.These investigations offer valuable insights into how combustion processes affect material,which is useful for designing engineering components under high-temperature environments.
基金This work was supported by Natural Science Foundation of Zhejiang Province(Grant No.Q23E050025)Huzhou Key Research and Development Project(Grant No.2022ZD2068)+5 种基金Scientific Research Fund of Zhejiang Provincial Education Department(Grant No.Y202145948)Huzhou University School-Level Scientific Research Projects(Grant No.2021XJKJ01)Cross Project of Zhejiang Fubai Material Technology Co.,Ltd(Grant No.HK33176)Cross Project of Zhejiang Aobo Quartz Technology Co.,Ltd(Grant No.HK33312),Zhejiang Province Basic Public Welfare Research Program(Grant No.LGG21E010002)Unveiling the Commander Special Plan for Scientific and Technological Research of Liaoning Province(Grant No.2021JH1/10400039)Science and Technology Research and Industrialization Project of Liaoning Province(Grant No.2020JH2/10200024).
文摘Subsoiling has been widely used all over the world as an important operation method of no-tillage farming.For energy-saving and life-extension,the tillage resistance and wear-corrosion of subsoilers have attracted wide attention.In this study,the tillage resistance,soil disturbance,wear and corrosion of subsoiler with S-T-SK-2#biomimetic structures(S means subsoiler;T means tine;SK means shank;2#,h/s=0.57,h=5 mm andα=45°.)and self-healing coating under two seasons,two locations with different soil properties(black loam and clay soil)and subsoiling speeds(2 km/h and 3.6 km/h)were investigated.The soil moisture content and compactness affected the tillage resistance and wear-corrosion.The tillage resistance and degree of corrosion on all subsoilers were much larger in clay soil than that in black loam soil.Compared with S-T-SK-2#,the tillage reduction rate of C-S-T-SK-2#(S-T-SK-2#with self-healing coating)was up to 14.32%in clay soil under the speed of 2 km/h.The significance tests of regression equation results showed that subsoiler type and soil properties had a significant impact on soil disturbance coefficient,swelling of total soil layer,bulkiness of the plough pan.It is of a guiding significance for the analysis of soil disturbance.Synergism mechanism of subsoiler coupling with biomimetic structures and self-healing coating was analyzed in following.It depicted the guiding effect of biomimetic structure and the shield function of self-healing coating,resulting in anticorrosion and wear resistance of subsoiler.
基金supported by the MoST of China (Grant No. 2011CB606404)the National Natural Science Foundation of China (Grant No. 50871114)
文摘Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys （e.g., the martensitic transformation temperature TM） sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C＇ is a better predictor of the composition dependent TM than the number of valence electrons per atom （e/a） since the general TM-C＇ correlation works for some of the alloys for which the TM-ela correlation fails, although there exist several cases for which both the general TM-C＇ and TM-ela correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated （5M） structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the marten- sites is examined by comparing their total energies. The non-modulated martensite β＇″ with the tetragonality of the unit cell c/a〉1 is shown to be globally stable whereas the 5M martensite with c/a〈1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reason- able agreement with experimental findings.
