High entropy alloys(HEAs)have excellent application prospects in catalysis because of their rich components and configuration space.In this work,we develop a Bayesian neural network(BNN)based on energies calculated wi...High entropy alloys(HEAs)have excellent application prospects in catalysis because of their rich components and configuration space.In this work,we develop a Bayesian neural network(BNN)based on energies calculated with density functional theory to search the configuration space of the CoNiRhRu HEA system.The BNN model was developed by considering six independent features of Co-Ni,Co-Rh,CoRu,Ni-Rh,Ni-Ru,and Rh-Ru in different shells and energies of structures as the labels.The root mean squared error of the energy predicted by BNN is 1.37 me V/atom.Moreover,the influence of feature periodicity on the energy of HEA in theoretical calculations is discussed.We found that when the neural network is optimized to a certain extent,only using the accuracy indicator of root mean square error to evaluate model performance is no longer accurate in some scenarios.More importantly,we reveal the importance of uncertainty quantification for neural networks to predict new structures of HEAs with proper confidence based on BNN.展开更多
Sulfur element possesses an ultrahigh theoretical specific capacity,while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products,limiting the...Sulfur element possesses an ultrahigh theoretical specific capacity,while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products,limiting the enhancement on energy density of lithium-sulfur batteries.Herein,for the first time,Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium-sulfur batteries.It is manifested that Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy nanocrystallites distributed on nitrogen-doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium polysulfides.In particular,benefiting from the accelerated kinetics by high-entropy alloy nanocrystallites and synergistic adsorption by nitrogen-doped carbon,the cathode exhibits high reversible capacity of 1079.5 mAh g_(-cathode)^(-1)(high utilization of 89.4%)with the whole cathode as active material,instead of sulfur element.Moreover,under both lean electrolyte(3μmg^(-1))and ultrahigh sulfur loading(27.0 mg cm^(-2))condition,the high discharge capacity of 868.2 mAh g_(-cathode)^(-1)can be still achieved for the sulfur cathode.This strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium-sulfur batteries.展开更多
This study aimed to investigate the microstructure and mechanical properties of TixZrVNb(x=1,1.5,2)refractory high-entropy alloys at room and elevated temperatures.The TiZrVNb alloy consisted of the body-centered cubi...This study aimed to investigate the microstructure and mechanical properties of TixZrVNb(x=1,1.5,2)refractory high-entropy alloys at room and elevated temperatures.The TiZrVNb alloy consisted of the body-centered cubic(bcc)matrix with a small amount of V2Zr phase.The Ti1.5ZrVNb and Ti2ZrVNb alloys exhibited a single-phase bcc structure.At room temperature,the tensile ductility of the as-cast alloys increased from 3.5%to 12.3%with the increase in the Ti content.The TixZrVNb alloys exhibited high yield strength at 600°C,and the ultimate yield strength was more than 900 MPa.Softening occurred at 800°C,but the ultimate yield strength could still exceed 200 MPa.Moreover,the TixZrVNb alloys displayed low densities but high specific yield strengths(SYSs).The lowest density of TixZrVNb alloys was only 6.12 g/cm^3,but the SYS could reach about 180 MPa·cm^3·g^−1,which is better than those of most reported high-entropy alloys(HEAs).展开更多
We prepared(CuCoFeNi)Tix(x=0,0.2,0.4,0.6,0.8,and 1.0)high-entropy alloys(HEAs)by vacuum arc melting and then investigated the effects of Ti on their microstructure and mechanical properties.When x was inreased to 0.6,...We prepared(CuCoFeNi)Tix(x=0,0.2,0.4,0.6,0.8,and 1.0)high-entropy alloys(HEAs)by vacuum arc melting and then investigated the effects of Ti on their microstructure and mechanical properties.When x was inreased to 0.6,the structure of the alloy transformed from their initial single face-centered cubic(fcc)structure into fcc+Laves mixed structure.The Laves phase was found to comprise Fe2Ti and be mainly distributed in the dendrite region.With increasing Ti content,both the Laves phase and the hardness of the alloy increased,whereas its yield and fracture strengths first increased and then decreased,reaching their highest value when x was 0.8.The(CuCoFeNi)Ti0.8 alloy exhibited the best overall mechanical properties,with yield and fracture strengths of 949.7 and 1723.4 MPa,respectively,a fracture strain of 27.92%,and a hardness of HV 461.6.展开更多
A new method of high-gravity combustion synthesis(HGCS)followed by post-treatment(PT)is reported for preparing high-performance high-entropy alloys(HEAs),Cr0.9FeNi2.5V0.2Al0.5 alloy,whereby cheap thermite powder is us...A new method of high-gravity combustion synthesis(HGCS)followed by post-treatment(PT)is reported for preparing high-performance high-entropy alloys(HEAs),Cr0.9FeNi2.5V0.2Al0.5 alloy,whereby cheap thermite powder is used as the raw material.In this process,the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field.Then,the master alloy is obtained after cooling.Subsequently,the master alloy is sequentially subjected to conventional vacuum arc melting(VAM),homogenization treatment,cold rolling,and annealing treatment to realize a tensile strength,yield strength,and elongation of 1250 MPa,1075 MPa,and 2.9%,respectively.The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating.Based on the calculation of phase separation kinetics in the high-temperature melt,it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.展开更多
Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu...Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu_(0.2) high-entropy alloy powders(HEAs)with both large aspect ratios and thin intergranular amorphous layers are constructed by a multistage mechanical alloying strategy,aiming to achieve excellent and temperature-stable permeability and EMW absorption.A single-phase face-centered cubic structure with good ductility and high crystallinity is obtained as wet milling precursors,via precisely controlling dry milling time.Then,HEAs are flattened to improve aspect ratios by synergistically regulating wet milling time.FeCoNiCr_(0.4)Cu_(0.2) HEAs with dry milling 20 h and wet milling 5 h(D20)exhibit higher and more stable permeability because of larger aspect ratios and thinner intergranular amorphous layers.The maximum reflection loss(RL)of D20/SiO_(2) composites is greater than-7 dB with 5 mm thickness,and EMW absorption bandwidth(RL<-7 dB)can maintain between 523 and 600 MHz from-50 to 150℃.Furthermore,relying on the“cocktail effect”of HEAs,D20 sample also exhibits excellent corrosion resistance and high Curie temperature.This work provides a facile and tunable strategy to design MHz electromagnetic absorbers with temperature stability,broadband,and resistance to harsh environments.展开更多
Tribology,which is the study of friction,wear,and lubrication,largely deals with the service performance of structural materials.For example,newly emerging high-entropy alloys(HEAs),which exhibit excellent hardness,an...Tribology,which is the study of friction,wear,and lubrication,largely deals with the service performance of structural materials.For example,newly emerging high-entropy alloys(HEAs),which exhibit excellent hardness,anti-oxidation,anti-softening ability,and other prop-erties,enrich the wear-resistance alloy family.To demonstrate the tribological behavior of HEAs systematically,this review first describes the basic tribological characteristics of single-,dual-,and multi-phase HEAs and HEA composites at room temperature.Then,it summarizes the strategies that improve the tribological property of HEAs.This review also discusses the tribological performance at elevated temperatures and provides a brief perspective on the future development of HEAs for tribological applications.展开更多
The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centere...The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centered-cubic and body-centered-cubic phases,presenting similar mechanical behavior as the as-cast state.The yield and tensile strengths of the alloys could be dramatically enhanced to^1205 MPa and^1318 MPa after 50%rolling reduction,respectively.A power-law relationship was discovered between the strain-hardening exponent and rolling reduction.The tensile strengths of this dual-phase HEA with different cold rolling treatments were predicted,mainly based on the Hollomon relationship,by the strain-hardening exponent,and showed good agreement with the experimental results.展开更多
Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatm...Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatment time.Boronizing remarkably improved the surface hardness from HV 188 to HV 1265 after treating at 900°C for 9 h.Moreover,boronizing enhanced the yield strength of HEAs from 195 to 265 MPa but deteriorated the tensile ductility.Multiple crackings in the boride layers significantly decreased the plasticity.The insufficient work-hardening capacity essentially facilitated the plastic instability of the boronized HEAs.With decreasing substrate thickness,the fracture modes gradually transformed from dimples to quasi-cleavage and eventually to cleavage.展开更多
High-entropy alloys(HEAs)have attracted increasing attention because of their unique properties,including high strength,hardness,chemical stability,and good wear resistance.Powder metallurgy is one of the most importa...High-entropy alloys(HEAs)have attracted increasing attention because of their unique properties,including high strength,hardness,chemical stability,and good wear resistance.Powder metallurgy is one of the most important methods used to fabricate HEA materials.This paper introduces the methods used to synthesize HEA powders and consolidate HEA bulk.The phase transformation,microstructural evolution,and mechanical properties of HEAs obtained by powder metallurgy are summarized.We also address HEA-related materials such as ceramic–HEA cermets and HEA-based composites fabricated by powder metallurgy.展开更多
New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructu...New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructures,and compressive properties of the alloys in the as-cast state were investigated.Results showed that both alloys were composed of BCC and cubic Laves phases.In terms of mechanical properties,the yield strength increased remarkably from 926 MPa for HfNbTaTiZr to 1258 MPa for CrHfNbTaTi,whereas a promising plastic strain of around 15.0%was retained in CrHfNbTaTi.The morphology and composition of the network-shaped interdendritic regions were closely related to the improved mechanical properties due to elemental substitution.Dendrites were surrounded by an incompact interdendritic shell after Mo incorporation,which deteriorated yield strength and accelerated brittleness.展开更多
High-entropy alloys(HEAs)are based on solid solutions which characterized by chemical short-range ordering(CSRO),but there is no accurate structural tool to address CSRO characteristic,which obstacles precise composit...High-entropy alloys(HEAs)are based on solid solutions which characterized by chemical short-range ordering(CSRO),but there is no accurate structural tool to address CSRO characteristic,which obstacles precise composition design for HEAs.In this study,based on the cluster-plus-glue-atoms model,the composition law of Al-TMs(TMs,transition metals)HEAs with BCC and FCC structures was revealed.In BCC structure,with five elements in equi-atomic ratio,the composition formula of Al-TMs HEAs can be expressed by a cluster formula[Al-M_(14)]Al_(3),and in non equi-atomic ratio can be expressed by[Al-M_(14)]Al,where M is the average atom of the TMs.But in FCC structure,both Al-TMs HEAs with five elements in equiatomic and non equi-atomic ratios can be expressed by a cluster formula[Al-M_(12)]Al.To confirm the effectiveness of cluster formula for Al-TMs,two alloys were designed,[Al-Ti_(4)V_(3)Nb_(4)Mo_(3)]Mo and[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al.Results show that the[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al alloy has both higher strength and higher plastic deformation at room temperature.Besides,[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al alloy shows slower soften effect at 800℃,contributed to its higher strength.By substituting Ta for some of Mo,the strength of[Al-Ti_(3)V_(3)Nb_(4)Mo_(3)Ta]Al at room temperature and high temperature drastically decreases,suggesting that Ta element deteriorates the properties of Al-TMs alloys.展开更多
The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermo...The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermoelectric devices and near-field imaging systems.In this paper,we design three structures(multilayer structure,nanoporous structure,and nanorod structure)based on high-entropy alloys to realize the enhancement of NFRHT.By combining stochastic electrodynamicsand Maxwell-Garnett's description of the effective medium,we calculate the radiative heat transfer under different parametersand find that the nanoporousstructure has the largest enhancement effect on NFRHT.The near-field heat transfer factor(q)of this structure(q=1.40×10^(9)W/(m^(2)·K))is three times higher than that of the planestructure(q=4.6×10^(8)W/(m^(2)·K)),and about two orders of magnitude higher than that of the SiO2plate.Thisresult providesa freshidea for the enhancement of NFRHT and will promote the application of high-entropy alloy materials in near-field heat radiation.展开更多
High-temperature oxidation is a common failure in high-temperature environments,which widely occur in aircraft engines and aerospace thrusters;as a result,the development of anti-high-temperature oxidation materials h...High-temperature oxidation is a common failure in high-temperature environments,which widely occur in aircraft engines and aerospace thrusters;as a result,the development of anti-high-temperature oxidation materials has been pursued.Ni-based alloys are a common high-temperature material;however,they are too expensive.High-entropy alloys are alternatives for the anti-oxidation property at high temperatures because of their special structure and properties.The recent achievements of high-temperature oxidation are reviewed in this paper.The high-temperature oxidation environment,temperature,phase structure,alloy elements,and preparation methods of high-entropy alloys are summarized.The reason why high-entropy alloys have anti-oxidation ability at high temperatures is illuminated.Current research,material selection,and application prospects of high-temperature oxidation are introduced.展开更多
Four FeCrNiMnMo_(x)(x=0,0.1,0.3,0.5,in molar ratio)high-entropy alloys(HEAs)were synthesized by vacuum arc melting to explore the potential impact of Mo on the microstructure,mechanical properties,and passivation and ...Four FeCrNiMnMo_(x)(x=0,0.1,0.3,0.5,in molar ratio)high-entropy alloys(HEAs)were synthesized by vacuum arc melting to explore the potential impact of Mo on the microstructure,mechanical properties,and passivation and electrochemical behaviors in 0.5 M H_(2)SO_(4)solution.The results display that the FeCrNiMn alloy exhibits a single face-centered cubic(FCC)structure while the microstructures of the FeCrNiMnMo_(0.1),FeCrNiMnMo_(0.3),and FeCrNiMnMo_(0.5)alloys consist of the FCC andσphase.The appear of theσphase ascribed to the addition of Mo enhances the hardness and yield strength with the sacrifice of plasticity.The FeCrNiMnMox HEAs achieve the maximum hardness of 414 HV_(0.2)and the highest compressive yield strength of 830 MPa when x=0.5,but compressive fracture strain is lowered to 10.8%.X-ray photoelectron spectroscopy(XPS)and electrochemical analysis show that the passivation film in FeCrNiMnMox alloy mainly consists of chromium oxides and molybdenum oxides.Mo has a beneficial effect on the corrosion resistance of the FeCrNiMnMox HEAs in a 0.5 M H_(2)SO_(4)solution by increasing the corrosion potential(E_(corr))and decreasing the corrosion current density(I_(corr))and passivation current density(I_(pass)).The FeCrNiMnMo_(0.1)alloy shows the best corrosion resistance,mainly due to its passivation film consisting of a large proportion of chromium oxide(Cr_(2)O_(3)).More Mo additions promote the formation of the precipitate ofσphase and the matrix regions depleted Cr and Mo elements adverse to the resistance to preferential localized corrosion.展开更多
Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHE...Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHEAs),which are difficult to synthesize and process by conventional methods.To evaluate a possible way to accelerate the process,high-throughput laser metal deposition was used in this work to prepare a quinary RHEA,TiZrNbHfTa,as well as its quaternary and ternary subsystems by in-situ alloying of elemental powders.Compositionally graded variants of the quinary RHEA were also analyzed.Our results show that the influence of various parameters such as powder shape and purity,alloy composition,and especially the solidification range,on the processability,microstructure,porosity,and mechanical properties can be investigated rapidly.The strength of these alloys was mainly affected by the oxygen and nitrogen contents of the starting powders,while substitutional solid solution strengthening played a minor role.展开更多
Because of the potential carcinogenic effects and difficult degradation of azo dyes, their degradation has been a longstanding problem. The degradation of azo dye Direct Blue 6(DB6) using ball-milled(BM) high-entropy ...Because of the potential carcinogenic effects and difficult degradation of azo dyes, their degradation has been a longstanding problem. The degradation of azo dye Direct Blue 6(DB6) using ball-milled(BM) high-entropy alloy(HEA) powders was characterized in this work. Newly designed AlFeMnTiM(M = Cr, Co, Ni) HEAs synthesized by mechanical alloying(MA) showed excellent performance in the degradation of azo dye DB6. The degradation efficiency of AlFeMnTiCr is approximately 19 times greater than that of the widely used commercial Fe–Si–B amorphous alloy ribbons and more than 100 times greater than that of the widely used commercial zero-valent iron(ZVI) powders. The galvanic-cell effect and the unique crystal structure are responsible for the good degradation performance of the BM HEAs. This study indicates that BM HEAs are attractive, valuable, and promising environmental catalysts for wastewater contaminated by azo dyes.展开更多
Refractory high-entropy alloys are considered as potential structural materials for elevated temperature applications.To obtain refractory high-entropy alloys with high strength,different amounts of Si were added into...Refractory high-entropy alloys are considered as potential structural materials for elevated temperature applications.To obtain refractory high-entropy alloys with high strength,different amounts of Si were added into the NbMoTiVW refractory high-entropy alloys.The effects of Si on the phase constitution,microstructure characteristics and mechanical properties of NbMoTiVWSi_(x) alloys were investigated.Results show that when the addition of Si is 0,0.025 and 0.05(molar ratio),the alloys are consisted of primary BCC and secondary BCC in the intergranular area.When the addition of Si is increased to 0.075 and 0.1,eutectic structure including silicide phase and secondary BCC phase is formed.The primary BCC phase shows dendritic morphology,and is refined by adding Si.The volume fraction of intergranular area is increased from 12.22%to 18.13%when the addition of Si increases from 0 to 0.1.The ultimate compressive strength of the NbMoTiVW alloy is improved from 2,242 MPa to 2,532 MPa.Its yield strength is also improved by the addition of Si,and the yield strength of NbMoTiVWSi_(0.1) reaches maximum of 2,298 MPa.However,the fracture strain of the alloy is decreased from 15.31%to 12.02%.The fracture mechanism of the alloys is changed from mixed fracture of ductile and quasi-cleavage to cleavage fracture with increasing of Si.The strengthening of alloys is attributed to the refinement of primary BCC phase,volume fraction increment of secondary BCC phase,and formation of eutectic structure by addition of Si.展开更多
High-entropy alloys(HEAs)are suitable for engineering applications requiring excellent mechanical,corrosion,thermal,and magnetic properties.In the last decade,electrodeposition has emerged as a promising synthesis tec...High-entropy alloys(HEAs)are suitable for engineering applications requiring excellent mechanical,corrosion,thermal,and magnetic properties.In the last decade,electrodeposition has emerged as a promising synthesis technique for HEAs.Research has focused on the influence of procedure parameters on the deposition of different HEA layers and the effect of their microstructure on their corrosion and magnetic properties.This review of current literature provides comprehensive information on HEAs and the use of direct and pulse electrodeposition as a synthesis technique for these materials.This review also addresses the research gaps on HEA production via electrodeposition,such as using other ceramic particles instead of graphene oxide in composite structures based on HEAs.展开更多
High-entropy alloys have been proved to be potential candidate materials in the biomedical field due to their balanced mechanical properties and excellent biocompatibility.The effects of atomic ratios on the as-cast m...High-entropy alloys have been proved to be potential candidate materials in the biomedical field due to their balanced mechanical properties and excellent biocompatibility.The effects of atomic ratios on the as-cast microstructural evolution,mechanical properties,and electrochemical property of TiZrTaNbSn high-entropy alloys were studied systematically.The crystal structure of TiZrTaNbSn high-entropy alloys is single BCC phase,and the microstructural evolution is based on atomic ratio.The dendric structure,peritectic structure,pseudo eutectic and equiaxed grain,which are associated with element segregation,can be obtained by non-equal atomic ratio.Ti_(30)Zr_(20)Ta_(20)Nb_(20)Sn_(10)alloy demonstrates a high compressive strength and fracture strain,which are 2,571.8 MPa and 12%,respectively,and the fracture behavior is quasicleavage faults.The Ti_(45)Zr_(35)Ta_(5)Nb_(5)Sn_(10),Ti_(30)Zr_(20)Ta_(20)Nb_(20)Sn_(10)and Ti_(35)Zr_(25)Ta_(15)Nb_(15)Sn_(10)alloys show excellent corrosion resistance according to Nyquist diagram,polarization curves and corrosion morphology.Compared with TiZrTaNbSn alloy,the corrosion rate of Ti_(45)Zr_(35)Ta_(5)Nb_(5)Sn_(10) alloy increases by about 98.9%.It can be concluded that non-equal atomic ratios are effective for microstructure control and performance optimization.展开更多
基金supported by the Shanghai Rising-Star Program (20QA1406800)the National Natural Science Foundation of China (22072091,91745102,92045301)。
文摘High entropy alloys(HEAs)have excellent application prospects in catalysis because of their rich components and configuration space.In this work,we develop a Bayesian neural network(BNN)based on energies calculated with density functional theory to search the configuration space of the CoNiRhRu HEA system.The BNN model was developed by considering six independent features of Co-Ni,Co-Rh,CoRu,Ni-Rh,Ni-Ru,and Rh-Ru in different shells and energies of structures as the labels.The root mean squared error of the energy predicted by BNN is 1.37 me V/atom.Moreover,the influence of feature periodicity on the energy of HEA in theoretical calculations is discussed.We found that when the neural network is optimized to a certain extent,only using the accuracy indicator of root mean square error to evaluate model performance is no longer accurate in some scenarios.More importantly,we reveal the importance of uncertainty quantification for neural networks to predict new structures of HEAs with proper confidence based on BNN.
基金Financial support from National Natural Science Foundation of China(21935006)is gratefully acknowledged。
文摘Sulfur element possesses an ultrahigh theoretical specific capacity,while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products,limiting the enhancement on energy density of lithium-sulfur batteries.Herein,for the first time,Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium-sulfur batteries.It is manifested that Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy nanocrystallites distributed on nitrogen-doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium polysulfides.In particular,benefiting from the accelerated kinetics by high-entropy alloy nanocrystallites and synergistic adsorption by nitrogen-doped carbon,the cathode exhibits high reversible capacity of 1079.5 mAh g_(-cathode)^(-1)(high utilization of 89.4%)with the whole cathode as active material,instead of sulfur element.Moreover,under both lean electrolyte(3μmg^(-1))and ultrahigh sulfur loading(27.0 mg cm^(-2))condition,the high discharge capacity of 868.2 mAh g_(-cathode)^(-1)can be still achieved for the sulfur cathode.This strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium-sulfur batteries.
基金the National Magnetic Confinement Fusion Energy R&D Program(No.2018YFE0312400)the National Natural Science Foundation of China(Nos.51822402 and 51671044)+3 种基金the National Key Research and Development Program of China(Nos.019YFA0209901 and 2018YFA0702901)the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University(Grant No.SKLSP201902)the Liaoning Revitalization Talents Program(No.XLYC1807047)the Fund of Science and Technology on Reactor Fuel and Materials Laboratory(No.STRFML-2020-04).
文摘This study aimed to investigate the microstructure and mechanical properties of TixZrVNb(x=1,1.5,2)refractory high-entropy alloys at room and elevated temperatures.The TiZrVNb alloy consisted of the body-centered cubic(bcc)matrix with a small amount of V2Zr phase.The Ti1.5ZrVNb and Ti2ZrVNb alloys exhibited a single-phase bcc structure.At room temperature,the tensile ductility of the as-cast alloys increased from 3.5%to 12.3%with the increase in the Ti content.The TixZrVNb alloys exhibited high yield strength at 600°C,and the ultimate yield strength was more than 900 MPa.Softening occurred at 800°C,but the ultimate yield strength could still exceed 200 MPa.Moreover,the TixZrVNb alloys displayed low densities but high specific yield strengths(SYSs).The lowest density of TixZrVNb alloys was only 6.12 g/cm^3,but the SYS could reach about 180 MPa·cm^3·g^−1,which is better than those of most reported high-entropy alloys(HEAs).
基金the National Natural Science Foundation of China(Nos.51604161 and 51604162)Hubei Key Laboratory of Hydroelectric Machinery Design&Maintenance Program(No.2019KJX10).
文摘We prepared(CuCoFeNi)Tix(x=0,0.2,0.4,0.6,0.8,and 1.0)high-entropy alloys(HEAs)by vacuum arc melting and then investigated the effects of Ti on their microstructure and mechanical properties.When x was inreased to 0.6,the structure of the alloy transformed from their initial single face-centered cubic(fcc)structure into fcc+Laves mixed structure.The Laves phase was found to comprise Fe2Ti and be mainly distributed in the dendrite region.With increasing Ti content,both the Laves phase and the hardness of the alloy increased,whereas its yield and fracture strengths first increased and then decreased,reaching their highest value when x was 0.8.The(CuCoFeNi)Ti0.8 alloy exhibited the best overall mechanical properties,with yield and fracture strengths of 949.7 and 1723.4 MPa,respectively,a fracture strain of 27.92%,and a hardness of HV 461.6.
基金the National Natural Science Foundation of China(No.51702332)the Key Research Projects in Gansu Province(No.17YF1GA020)the CAS Key Laboratory of Cryogenics,Technical Institute of Physics and Chemistry(Youth Innovation Fund No.CRYOQN201705).
文摘A new method of high-gravity combustion synthesis(HGCS)followed by post-treatment(PT)is reported for preparing high-performance high-entropy alloys(HEAs),Cr0.9FeNi2.5V0.2Al0.5 alloy,whereby cheap thermite powder is used as the raw material.In this process,the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field.Then,the master alloy is obtained after cooling.Subsequently,the master alloy is sequentially subjected to conventional vacuum arc melting(VAM),homogenization treatment,cold rolling,and annealing treatment to realize a tensile strength,yield strength,and elongation of 1250 MPa,1075 MPa,and 2.9%,respectively.The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating.Based on the calculation of phase separation kinetics in the high-temperature melt,it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.
基金the Supported by Program for the National Natural Science Foundation of China(No.52071053,U1704253,52103334)China Postdoctoral Science Foundation(2020M670748,2020M680946)the Fundamental Research Funds for the Central Universities(DUT20GF111).
文摘Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu_(0.2) high-entropy alloy powders(HEAs)with both large aspect ratios and thin intergranular amorphous layers are constructed by a multistage mechanical alloying strategy,aiming to achieve excellent and temperature-stable permeability and EMW absorption.A single-phase face-centered cubic structure with good ductility and high crystallinity is obtained as wet milling precursors,via precisely controlling dry milling time.Then,HEAs are flattened to improve aspect ratios by synergistically regulating wet milling time.FeCoNiCr_(0.4)Cu_(0.2) HEAs with dry milling 20 h and wet milling 5 h(D20)exhibit higher and more stable permeability because of larger aspect ratios and thinner intergranular amorphous layers.The maximum reflection loss(RL)of D20/SiO_(2) composites is greater than-7 dB with 5 mm thickness,and EMW absorption bandwidth(RL<-7 dB)can maintain between 523 and 600 MHz from-50 to 150℃.Furthermore,relying on the“cocktail effect”of HEAs,D20 sample also exhibits excellent corrosion resistance and high Curie temperature.This work provides a facile and tunable strategy to design MHz electromagnetic absorbers with temperature stability,broadband,and resistance to harsh environments.
基金the National Nat-ural Science Foundation of China(Nos.51901013,52071023,and 52122408)the State Key Lab of Advanced Metals and Materials(No.2020-Z16)the Fundamental Research Funds for the Central Universities(University of Science and Technology Beijing)(No.06500135).
文摘Tribology,which is the study of friction,wear,and lubrication,largely deals with the service performance of structural materials.For example,newly emerging high-entropy alloys(HEAs),which exhibit excellent hardness,anti-oxidation,anti-softening ability,and other prop-erties,enrich the wear-resistance alloy family.To demonstrate the tribological behavior of HEAs systematically,this review first describes the basic tribological characteristics of single-,dual-,and multi-phase HEAs and HEA composites at room temperature.Then,it summarizes the strategies that improve the tribological property of HEAs.This review also discusses the tribological performance at elevated temperatures and provides a brief perspective on the future development of HEAs for tribological applications.
基金the Natural Science Foundation of Shanxi Province,China(Nos.201901D111105 and 201901D111114)Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi Province,China(2019)+2 种基金the Opening Project of the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(No.KFJJ20-13M)the Graduate Science and Technology Innovation Fund Project of Shanxi Province,China(No.2019BY044)the State Key Lab of Advanced Metals and Materials of China(No.2020-Z09).
文摘The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centered-cubic and body-centered-cubic phases,presenting similar mechanical behavior as the as-cast state.The yield and tensile strengths of the alloys could be dramatically enhanced to^1205 MPa and^1318 MPa after 50%rolling reduction,respectively.A power-law relationship was discovered between the strain-hardening exponent and rolling reduction.The tensile strengths of this dual-phase HEA with different cold rolling treatments were predicted,mainly based on the Hollomon relationship,by the strain-hardening exponent,and showed good agreement with the experimental results.
基金National Key Laboratory for Remanufacturing,Academy of Armored Forces Engineering(No.61420050204)the Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi,China(No.2019BY044)Jinxiong Hou would like to acknowledge the financial support from the Graduate Science and Technology Innovation Fund Project of Shanxi,China(No.2019BY044).
文摘Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatment time.Boronizing remarkably improved the surface hardness from HV 188 to HV 1265 after treating at 900°C for 9 h.Moreover,boronizing enhanced the yield strength of HEAs from 195 to 265 MPa but deteriorated the tensile ductility.Multiple crackings in the boride layers significantly decreased the plasticity.The insufficient work-hardening capacity essentially facilitated the plastic instability of the boronized HEAs.With decreasing substrate thickness,the fracture modes gradually transformed from dimples to quasi-cleavage and eventually to cleavage.
基金The authors are grateful to the National Key Research and Development Plan of China(No.2017YF130310400)the National Natural Science Foundation of China(Nos.51521001 and 51902233)+1 种基金the Self-determined and Innovative Research Funds of WHUT(Nos.2018III020 and 2018IVA094)the Students Innovation and Entrepreneurship Training Program of WHUT(Nos.2018CLA127 and 20181049701037).
文摘High-entropy alloys(HEAs)have attracted increasing attention because of their unique properties,including high strength,hardness,chemical stability,and good wear resistance.Powder metallurgy is one of the most important methods used to fabricate HEA materials.This paper introduces the methods used to synthesize HEA powders and consolidate HEA bulk.The phase transformation,microstructural evolution,and mechanical properties of HEAs obtained by powder metallurgy are summarized.We also address HEA-related materials such as ceramic–HEA cermets and HEA-based composites fabricated by powder metallurgy.
基金supported by the National Natural Science Foundation of China(No.51604173)the Natural Science Foundation of Jiangsu Higher Education Institution of China(No.18KJB430012)。
文摘New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructures,and compressive properties of the alloys in the as-cast state were investigated.Results showed that both alloys were composed of BCC and cubic Laves phases.In terms of mechanical properties,the yield strength increased remarkably from 926 MPa for HfNbTaTiZr to 1258 MPa for CrHfNbTaTi,whereas a promising plastic strain of around 15.0%was retained in CrHfNbTaTi.The morphology and composition of the network-shaped interdendritic regions were closely related to the improved mechanical properties due to elemental substitution.Dendrites were surrounded by an incompact interdendritic shell after Mo incorporation,which deteriorated yield strength and accelerated brittleness.
基金supported by the National Key Research and Development Program of China(Grant Nos.2020YFB2008305,2020YFB2008303).
文摘High-entropy alloys(HEAs)are based on solid solutions which characterized by chemical short-range ordering(CSRO),but there is no accurate structural tool to address CSRO characteristic,which obstacles precise composition design for HEAs.In this study,based on the cluster-plus-glue-atoms model,the composition law of Al-TMs(TMs,transition metals)HEAs with BCC and FCC structures was revealed.In BCC structure,with five elements in equi-atomic ratio,the composition formula of Al-TMs HEAs can be expressed by a cluster formula[Al-M_(14)]Al_(3),and in non equi-atomic ratio can be expressed by[Al-M_(14)]Al,where M is the average atom of the TMs.But in FCC structure,both Al-TMs HEAs with five elements in equiatomic and non equi-atomic ratios can be expressed by a cluster formula[Al-M_(12)]Al.To confirm the effectiveness of cluster formula for Al-TMs,two alloys were designed,[Al-Ti_(4)V_(3)Nb_(4)Mo_(3)]Mo and[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al.Results show that the[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al alloy has both higher strength and higher plastic deformation at room temperature.Besides,[Al-Ti_(3)V_(3)Nb_(4)Mo_(4)]Al alloy shows slower soften effect at 800℃,contributed to its higher strength.By substituting Ta for some of Mo,the strength of[Al-Ti_(3)V_(3)Nb_(4)Mo_(3)Ta]Al at room temperature and high temperature drastically decreases,suggesting that Ta element deteriorates the properties of Al-TMs alloys.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.52101233,51931007,and 52071279)the Hebei Natural Science Foundation(No.E2022203010)the Innovation Capability Improvement Project of Hebei Province(No.22567605H).
文摘The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermoelectric devices and near-field imaging systems.In this paper,we design three structures(multilayer structure,nanoporous structure,and nanorod structure)based on high-entropy alloys to realize the enhancement of NFRHT.By combining stochastic electrodynamicsand Maxwell-Garnett's description of the effective medium,we calculate the radiative heat transfer under different parametersand find that the nanoporousstructure has the largest enhancement effect on NFRHT.The near-field heat transfer factor(q)of this structure(q=1.40×10^(9)W/(m^(2)·K))is three times higher than that of the planestructure(q=4.6×10^(8)W/(m^(2)·K)),and about two orders of magnitude higher than that of the SiO2plate.Thisresult providesa freshidea for the enhancement of NFRHT and will promote the application of high-entropy alloy materials in near-field heat radiation.
基金This work was financially supported by the National Natural Science Foundation of China(No.52071014)the Fundamental Research Funds for the Central Universities(No.FRF-GF-19-033BZ)the National Key Research and Development Program of China(No.2020YFB0704501).
文摘High-temperature oxidation is a common failure in high-temperature environments,which widely occur in aircraft engines and aerospace thrusters;as a result,the development of anti-high-temperature oxidation materials has been pursued.Ni-based alloys are a common high-temperature material;however,they are too expensive.High-entropy alloys are alternatives for the anti-oxidation property at high temperatures because of their special structure and properties.The recent achievements of high-temperature oxidation are reviewed in this paper.The high-temperature oxidation environment,temperature,phase structure,alloy elements,and preparation methods of high-entropy alloys are summarized.The reason why high-entropy alloys have anti-oxidation ability at high temperatures is illuminated.Current research,material selection,and application prospects of high-temperature oxidation are introduced.
文摘Four FeCrNiMnMo_(x)(x=0,0.1,0.3,0.5,in molar ratio)high-entropy alloys(HEAs)were synthesized by vacuum arc melting to explore the potential impact of Mo on the microstructure,mechanical properties,and passivation and electrochemical behaviors in 0.5 M H_(2)SO_(4)solution.The results display that the FeCrNiMn alloy exhibits a single face-centered cubic(FCC)structure while the microstructures of the FeCrNiMnMo_(0.1),FeCrNiMnMo_(0.3),and FeCrNiMnMo_(0.5)alloys consist of the FCC andσphase.The appear of theσphase ascribed to the addition of Mo enhances the hardness and yield strength with the sacrifice of plasticity.The FeCrNiMnMox HEAs achieve the maximum hardness of 414 HV_(0.2)and the highest compressive yield strength of 830 MPa when x=0.5,but compressive fracture strain is lowered to 10.8%.X-ray photoelectron spectroscopy(XPS)and electrochemical analysis show that the passivation film in FeCrNiMnMox alloy mainly consists of chromium oxides and molybdenum oxides.Mo has a beneficial effect on the corrosion resistance of the FeCrNiMnMox HEAs in a 0.5 M H_(2)SO_(4)solution by increasing the corrosion potential(E_(corr))and decreasing the corrosion current density(I_(corr))and passivation current density(I_(pass)).The FeCrNiMnMo_(0.1)alloy shows the best corrosion resistance,mainly due to its passivation film consisting of a large proportion of chromium oxide(Cr_(2)O_(3)).More Mo additions promote the formation of the precipitate ofσphase and the matrix regions depleted Cr and Mo elements adverse to the resistance to preferential localized corrosion.
基金GL and ELG acknowledge funding from the German Research Foundation in the framework of the priority program SPP 2006—Compositionally Complex Alloys—High Entropy Alloys,projects LA 3607/3-1 and GU 1075/12-1.EPG is supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Division.
文摘Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHEAs),which are difficult to synthesize and process by conventional methods.To evaluate a possible way to accelerate the process,high-throughput laser metal deposition was used in this work to prepare a quinary RHEA,TiZrNbHfTa,as well as its quaternary and ternary subsystems by in-situ alloying of elemental powders.Compositionally graded variants of the quinary RHEA were also analyzed.Our results show that the influence of various parameters such as powder shape and purity,alloy composition,and especially the solidification range,on the processability,microstructure,porosity,and mechanical properties can be investigated rapidly.The strength of these alloys was mainly affected by the oxygen and nitrogen contents of the starting powders,while substitutional solid solution strengthening played a minor role.
基金financially supported by the National Natural Science Foundation of China(No.51671056)Jiangsu Key Laboratory for Advanced Metallic Materials(No.BM2007204)
文摘Because of the potential carcinogenic effects and difficult degradation of azo dyes, their degradation has been a longstanding problem. The degradation of azo dye Direct Blue 6(DB6) using ball-milled(BM) high-entropy alloy(HEA) powders was characterized in this work. Newly designed AlFeMnTiM(M = Cr, Co, Ni) HEAs synthesized by mechanical alloying(MA) showed excellent performance in the degradation of azo dye DB6. The degradation efficiency of AlFeMnTiCr is approximately 19 times greater than that of the widely used commercial Fe–Si–B amorphous alloy ribbons and more than 100 times greater than that of the widely used commercial zero-valent iron(ZVI) powders. The galvanic-cell effect and the unique crystal structure are responsible for the good degradation performance of the BM HEAs. This study indicates that BM HEAs are attractive, valuable, and promising environmental catalysts for wastewater contaminated by azo dyes.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001114,51825401)Cultivation Program for Outstanding Young Teacher in Henan Province(Grant Nos.21420152,2021GGJS064)+2 种基金Scientific Research Fund of State Key Laboratory of Materials Processing and Die&Mould Technology(Grant No.P2020-023)Program for Guangdong Introducing Innovative and Entrepreneurial Teams(Grant No.2016ZT06G025)the Project of Science and Technology in Henan Province(Grant No.192102210011).
文摘Refractory high-entropy alloys are considered as potential structural materials for elevated temperature applications.To obtain refractory high-entropy alloys with high strength,different amounts of Si were added into the NbMoTiVW refractory high-entropy alloys.The effects of Si on the phase constitution,microstructure characteristics and mechanical properties of NbMoTiVWSi_(x) alloys were investigated.Results show that when the addition of Si is 0,0.025 and 0.05(molar ratio),the alloys are consisted of primary BCC and secondary BCC in the intergranular area.When the addition of Si is increased to 0.075 and 0.1,eutectic structure including silicide phase and secondary BCC phase is formed.The primary BCC phase shows dendritic morphology,and is refined by adding Si.The volume fraction of intergranular area is increased from 12.22%to 18.13%when the addition of Si increases from 0 to 0.1.The ultimate compressive strength of the NbMoTiVW alloy is improved from 2,242 MPa to 2,532 MPa.Its yield strength is also improved by the addition of Si,and the yield strength of NbMoTiVWSi_(0.1) reaches maximum of 2,298 MPa.However,the fracture strain of the alloy is decreased from 15.31%to 12.02%.The fracture mechanism of the alloys is changed from mixed fracture of ductile and quasi-cleavage to cleavage fracture with increasing of Si.The strengthening of alloys is attributed to the refinement of primary BCC phase,volume fraction increment of secondary BCC phase,and formation of eutectic structure by addition of Si.
文摘High-entropy alloys(HEAs)are suitable for engineering applications requiring excellent mechanical,corrosion,thermal,and magnetic properties.In the last decade,electrodeposition has emerged as a promising synthesis technique for HEAs.Research has focused on the influence of procedure parameters on the deposition of different HEA layers and the effect of their microstructure on their corrosion and magnetic properties.This review of current literature provides comprehensive information on HEAs and the use of direct and pulse electrodeposition as a synthesis technique for these materials.This review also addresses the research gaps on HEA production via electrodeposition,such as using other ceramic particles instead of graphene oxide in composite structures based on HEAs.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001262,52071188,52171120)Key Research and Development Project of Shanxi Province(Grant No.2021SF-297)Zhejiang Province Natural Science Foundation of China(Grant Nos.ZY22E010293,LQ20E010003).
文摘High-entropy alloys have been proved to be potential candidate materials in the biomedical field due to their balanced mechanical properties and excellent biocompatibility.The effects of atomic ratios on the as-cast microstructural evolution,mechanical properties,and electrochemical property of TiZrTaNbSn high-entropy alloys were studied systematically.The crystal structure of TiZrTaNbSn high-entropy alloys is single BCC phase,and the microstructural evolution is based on atomic ratio.The dendric structure,peritectic structure,pseudo eutectic and equiaxed grain,which are associated with element segregation,can be obtained by non-equal atomic ratio.Ti_(30)Zr_(20)Ta_(20)Nb_(20)Sn_(10)alloy demonstrates a high compressive strength and fracture strain,which are 2,571.8 MPa and 12%,respectively,and the fracture behavior is quasicleavage faults.The Ti_(45)Zr_(35)Ta_(5)Nb_(5)Sn_(10),Ti_(30)Zr_(20)Ta_(20)Nb_(20)Sn_(10)and Ti_(35)Zr_(25)Ta_(15)Nb_(15)Sn_(10)alloys show excellent corrosion resistance according to Nyquist diagram,polarization curves and corrosion morphology.Compared with TiZrTaNbSn alloy,the corrosion rate of Ti_(45)Zr_(35)Ta_(5)Nb_(5)Sn_(10) alloy increases by about 98.9%.It can be concluded that non-equal atomic ratios are effective for microstructure control and performance optimization.