Lithium-sulfur(Li-S)batteries are considered a potential candidate for next-generation energy-dense and sustainable energy storage.However,the slow conversion and severe shuttle of polysulfides(LiPSs)result in rapid p...Lithium-sulfur(Li-S)batteries are considered a potential candidate for next-generation energy-dense and sustainable energy storage.However,the slow conversion and severe shuttle of polysulfides(LiPSs)result in rapid performance degradation over long-term cycling.Herein,we report a high-entropy single-atom(HE-SA)catalyst to regulate the multi-step conversion of LiPS to attain a high-performance Li-S battery.Both the density functional theory calculations and the experimental results prove that the Fe atomic site with high spin configurations strongly interacts with Li_(2)S_(4)through d-p and s-p synergistic orbital hybridization which facilitates the reduction of LiPS.Moreover,S-dominant p-d hybridization between Li_(2)S and a high-spin Mn site weakens the Li-S bond and facilitates the rapid sulfur evolution reaction.Consequently,the Li-S battery with a bifunctional HE-SA catalyst shows an ultralow capacity decay of 0.026% per cycle over 1900 cycles at 1 C.This work proposes a high-entropy strategy for sculpting electronic structures to enable spin and orbital hybridization modulation in advanced catalysts toward longcycling Li-S batteries.展开更多
High-entropy spinel oxides are promising anode materials for lithium-ion batteries owing to their unique crystal structures,which provide enhanced structural stability,multiple redox-active sites,and three-dimensional...High-entropy spinel oxides are promising anode materials for lithium-ion batteries owing to their unique crystal structures,which provide enhanced structural stability,multiple redox-active sites,and three-dimensional Li^(+)diffusion pathways.However,the intrinsic complexity and compositional diversity of high-entropy systems have limited a comprehensive understanding of the correlation between crystal structure,elemental composition,and rate performance,thereby impeding further optimization and practical application.展开更多
The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conduc...The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conductivities of high-entropy ceramics(HECs).Although RE_(3)MO_(7) (RE represents rare-earth elements;M is Ta or Nb) ceramics have been widely studied for use in thermal barrier coatings and solid oxide fuel cells,their application scope can be broadened through the effective manipulation of the thermal/oxygen ionic conductivities.Herein,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))_(3)Ta_(1/2)Nb_(1/2)O_(7) HECs are designed and synthesized.These ceramics exhibit lower thermal conductivity and higher oxygen ionic conductivity than pristine ordered RE_(3)MO_(7) ceramics.Characterization results prove that high-entropy effects in the prepared material enhance atomic displacement parameters(ADPs),causing an increase in the oxygen ionic conductivity by a factor of 10 and enhancement in the phonon scattering rate,thereby reducing thermal conductivity by increasing ADPs.The ADPs can act as an indicator of the anharmonic vibration strength of the lattice,affecting the thermal/oxygen ionic conductivity and thermal expansion coefficient.Furthermore,in nano-indentation tests,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))3Ta_(1/2)Nb_(1/2)O_(7) HECs show high hardness(11.8 GPa),toughness(2.0 MPa·m^(1/2)),and modulus(215.0 GPa),which are beneficial for structural/functional applications.Overall,the obtained results indicate that thermal/oxygen ionic transport mechanisms can be used to further improve the properties and thereby expand the application scope of various HECs.展开更多
The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as...The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.展开更多
Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simula...Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simulations to explore the CSRO effect on the generation and evolution behaviors of irradiation defects.The results demonstrate that CSRO can suppress the formation of Frenkel pairs in TiVTaNb HEAs,with the suppression effect becoming more pronounced as the degree of CSRO increases.CSRO can change the types of interstitial defects generated during cascade collisions.Specifically,as the degree of CSRO increases,the proportion of Ti-related interstitials shows a marked enhancement,primarily evidenced by a significant rise in Ti–Ti dumbbells accompanied by a corresponding decrease in Ti–V dumbbells.CSRO exhibits negligible influence on defect clustering and the nucleation and evolution of dislocation loops.Regardless of CSRO conditions,TiVTaNb HEAs preserve exceptional radiation tolerance throughout the cascade damage process,suggesting that the intrinsic properties of this multi-principal element system dominate its radiation response.These findings provide fundamental insights into the CSRO effect on defect formation and evolution behaviors in HEAs,which may provide new design strategies for high-entropy alloys.展开更多
Refractory high-entropy alloys(RHEAs)are promising for high-temperature applications due to their ex-ceptional mechanical properties at high temperatures.However,limited studies on their high-temperature fatigue behav...Refractory high-entropy alloys(RHEAs)are promising for high-temperature applications due to their ex-ceptional mechanical properties at high temperatures.However,limited studies on their high-temperature fatigue behavior hinder further development.This study systematically investigates the low-cycle fatigue(LCF)behavior of HfNbTiZr RHEA at room temperature(25℃)and elevated temperatures(350,450,and 600℃)through a combination of experimental analyses and dislocation-based damage-coupled crystal plasticity finite element(CPFE)simulations,to unveil the effects of creep damage on LCF behavior at varying temperatures.The results indicate that the LCF life dramatically decreases at an increased tem-perature,shifting from transgranular fatigue damage at lower temperatures(25-350℃)to a dual damage mechanism involving both intergranular fatigue and creep damage at higher temperatures(450-600℃).At 600℃,creep damage notably contributes to the accumulation of geometrically necessary dislocations(GNDs),crack initiation,and propagation at grain boundaries,and thus accelerates LCF failure.Compara-tive CPFE simulations reveal that creep damage significantly contributes to cyclic softening and reduction in elastic modulus,which also amplifies the strain localization under the LCF loading.The contribution of creep damage to the total stored energy density(SED)representing the overall damage increases with temperatures,accounting for 11%at 600℃.Additionally,CPFE simulations indicate that the creep dam-age notably influences the magnitude of GND density localized at grain boundaries.This study provides critical insights into the fatigue damage mechanisms of RHEAs,offering valuable guidance for their ap-plication in high temperatures.展开更多
In the present study,AlCoCrFeNi_(2.1)eutectic high-entropy alloy(EHEA)has been fabricated by laser melting deposition(LMD).The influence of laser energy density on microstructures,wear resistance and corrosion resista...In the present study,AlCoCrFeNi_(2.1)eutectic high-entropy alloy(EHEA)has been fabricated by laser melting deposition(LMD).The influence of laser energy density on microstructures,wear resistance and corrosion resistance of the alloy was systematically explored.The results indicate that the AlCoCrFeNi_(2.1)EHEA exhibited lamellar eutectic microstructures with alternating FCC and BCC phases.With the increase in laser energy density,the alloy grain size,interlamellar spacing,and volume fraction of the FCC phase increased,while the hardness of the alloy decreased.Meanwhile,the tribological performance of the alloy deteriorated with increasing laser energy density,and the combined effects of abrasive wear and adhesive wear gradually became significant.In addition,increasing laser energy density from 18.2 to 25 J/mm^(2)resulted in the increase in corrosion current density of the AlCoCrFeNi_(2.1)EHEA from 6.36×10^(−8) to 3.02×10^(−7) A/cm^(2)and the negative shift of corrosion potential from−211 to−292 mV(SCE).In summary,reducing laser energy density improved the wear and corrosion performance of the additively manufactured AlCoCrFeNi_(2.1)EHEA.展开更多
Four machine learning algorithms were used to predict the solid solution phases of high-entropy alloys(HEAs).To improve the model accuracy,the K-fold cross validation was adopted.Results show that the K-nearest neighb...Four machine learning algorithms were used to predict the solid solution phases of high-entropy alloys(HEAs).To improve the model accuracy,the K-fold cross validation was adopted.Results show that the K-nearest neighbor algorithm can effectively distinguish body-centered cubic(bcc)phase,face-centered cubic(fcc)phase,and mixed(fcc+bcc)phase,and the accuracy rate is approximately 93%.Thereafter,CoCrFeNi_(2)Al_(x)(x=0,0.1,0.3,1.0)HEAs were prepared and characterized by X-ray diffractometer and energy disperse spectrometer.It is found that their phases are transformed from fcc phase to fcc+bcc phase,which is consistent with the prediction results of machine learning.Furthermore,the influence of Al content on the microstructure and tribological properties of CoCrFeNi_(2)Al_(x)(x=0,0.1,0.3,1.0)HEAs was evaluated.Results reveal that with the increase in Al content,the nanohardness and microhardness increase by approximately 45%and 75%,respectively.The elastic limit parameter H/Er increases from 0.0216 to 0.030,whereas the plastic deformation resistance parameter H^(3)/E_(r)^(2) increases from 0.0014 to 0.0045,which demonstrates an improvement in nanohardness with the increase in Al addition amount.In addition,the wear rate decreases by 35%with the increase in Al addition amount.This research provides a new idea with energy-saving and time-reduction characteristics to prepare HEAs.展开更多
The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at c...The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at current density of 60 A/mm^(2) and strain rate of 0.1 s^(−1),the ultimate tensile stress shows a significant decrease from approximately 3000 MPa to 1900 MPa with reduction ratio of about 36.7%.However,as current density increases,elongation decreases due to intermediate temperature embrittlement.This is because the current induces Joule effect,which then leads to stress concentration and more defect formation.Moreover,the flow stress is decreased with the increase in strain rate at constant current density.展开更多
(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co co...(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.展开更多
Electrocatalytic reduction of nitrate to ammonia offers an environmentally friendly and sustainable approach for ammonia production,but it involves a multi-step reaction process with complex intermediates,and still fa...Electrocatalytic reduction of nitrate to ammonia offers an environmentally friendly and sustainable approach for ammonia production,but it involves a multi-step reaction process with complex intermediates,and still faces the challenge of high activity and high selectivity.Herein,a high-entropy nanoalloy was synthesized via high-temperature annealing of metal salt with dopamine as a carbon source for electrocatalytic reduction of nitrate to ammonia.The FeCoNiCuRu_(1.5)/C catalyst displays a conversion rate of 90.2%and an ammonia selectivity of 92.2% at-0.74 V(vs.RHE),significantly surpassing the performance of lowentropy alloys such as FeCo/C by 1.5–2 times.Moreover,FeCoNiCuRu_(1.5)/C maintains a consistent nitrate conversion rate of about 90.0% after 120 h of continuous operation(10 cycles),indicating high stability.The superior performance of FeCoNiCuRu_(1.5)/C can be attributed to the synergetic relay catalysis among Fe,Co,Ni,Cu,and Ru sites.This synergy enhances nitrate adsorption due to the optimized electronic structure of multiple active sites,which facilitates the nitrate reduction to intermediates.Subsequently,the effective active hydrogen produced at the Ru site,in conjunction with adjustments at other metal sites,promotes the selective transformation of the intermediates into ammonia.This work not only highlights the efficacy of synergetic relay electrocatalysis but also opens new avenues for developing highly efficient multi-site catalysts.展开更多
Creep is an important mechanical property of refractory high-entropy alloys(RHEAs)at high temperatures.The existence of short-range order(SRO)and its ability to improve the strength or plasticity of high-entropy alloy...Creep is an important mechanical property of refractory high-entropy alloys(RHEAs)at high temperatures.The existence of short-range order(SRO)and its ability to improve the strength or plasticity of high-entropy alloys(HEAs)have been experimentally proven.However,there is still little research on the correlation between SRO and creep behavior.The mechanism of SRO influencing creep behavior is not yet clear.In this work,the creep behaviors of TiVTaNb RHEA with and without SRO were simulated at various temperatures and stresses using molecular dynamics methods,and the effects of SRO on creep behavior were analyzed.The results show that the SRO is energetically favorable for occurrence in this RHEA.For polycrystalline RHEAs,grain boundary energy is an important driving force for the formation of SRO.Significantly,under the same conditions,the SRO can reduce the steady-state creep rate and change the creep mechanism of the RHEA.Specifically,the models with SRO will exhibit lower stress exponent and grain-size exponent.A mechanism by which SRO reduces the effects of grain boundaries on creep has been discovered.These phenomena can be well explained by the effects of SRO on atomic diffusion.In addition,by analyzing the diffusion ability of different elements,SRO can induce localization of atomic diffusion,resulting in strain localization under high stresses.This work highlights the importance of SRO on the creep of RHEAs and provides a reference for establishing a reasonable creep model of RHEAs.展开更多
Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and w...Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and wear properties of Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were systematically investigated.Al_(0.5)CrFeNi_(2.5)HEA exhibits a face-centered cubic(FCC)matrix with Ni3Al-type ordered nanoprecipitates.When Si was doped,σphase and Cr-rich nanoprecipitates existed in the B2 matrix and L12 in the FCC matrix.The nanohardness was increased from 4.67 to 5.45 GPa with doping of Si,which is associated with forming the new phases and improved nanohardness of L12/FCC phases.The coefficient of friction(COF)value was reduced from 0.75 to 0.67 by adding Si.σphase and Cr-rich nanoprecipitates in B2 matrix support a decreased wear rate from 7.87×10^(-4) to 6.82×10^(-4) mm^(3)/(N m).Furthermore,the main wear mechanism of Al_(0.5)CrFeNi_(2.5)and Al_(0.5)CrFeNi_(2.5)Si0.25 HEAs is abrasive wear.展开更多
FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)af...FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)affected the microstructures of the thin films and their mechanical and corrosion properties.Compared with the FeCoCrMnNi thin films with 1-sccm N_(2),the addition of 2 and 3 sccm of N_(2)by as much as 5.45at%and 6.34at%changed the solid solution’s crystalline structure into an amorphous structure.The addition of nitro-gen caused drastic changes to the surface morphology,creating a smoother and more uniform surface without cauliflower units.The atomic force microscopy image analysis indicated that the addition of nitrogen reduced the surface roughness from 5.58 to 1.82 nm.Adding N_(2)to the CoCrFeMnNi thin film helped increase its mechanical properties,such as hardness and strength,while the Young’s modulus decreased.The hardness of(8.75±0.5)GPa and the reduced Young’s modulus of(257.37±11.4)GPa of the FeCoCrMnNi thin film reached(12.67±1.2)and(194.39±12.4)GPa,respectively,with 1 sccm N_(2).The applied coating of the CoCrFeMnNi thin film on 304SUS increased the corrosion resistance,whereas the addition of nitrogen to the CoCrFeMnNi thin film also improved its corrosion res-istance compared with that of the CoCrFeMnNi thin film without nitrogen.展开更多
The short-range ordering(SRO)structure has been considered as a toughening method to improve the mechanical properties of high-entropy alloys(HEAs).However,the strengthening mechanism of the SRO structures on the HEAs...The short-range ordering(SRO)structure has been considered as a toughening method to improve the mechanical properties of high-entropy alloys(HEAs).However,the strengthening mechanism of the SRO structures on the HEAs still needs to be further revealed.Here,the effect of element distribution,Al content,crack orientation,temperature,and strain rate on the crack propagation behavior of the AlxFeCoCrNi HEAs are investigated using Monte Carlo(MC)/molecular dynamics(MD)simulation methods.Two HEA models are considered,one with five elements randomly distributed in the alloys,i.e.RSS_HEAs,and the other presenting SRO structure in the alloys,namely SRO_HEAs.The results show that Al atoms play a decisive role in the SRO degree of the HEA.The higher the Al content,the greater the SRO degree of the HEA,and the stronger the resistance of the SRO structure to crack propagation in the alloys.The results indicate that the reinforcement effect of the SRO structure in the model with the(111)[110]crack is more significant than that with the(111)[110]crack.The results show that the crack length of the alloys at maximum strain does not monotonically increase with temperature,but rather exhibits a turning point at the temperature of 400 K.When the temperature is below 400 K,the crack length of the alloys increases with the increase of temperature,while above 400 K,the opposite trend appears.In addition,the results indicate that the crack length of the alloys decreases with increasing strain rate under the same strain.展开更多
The extraordinary high-temperature strength of refractory high-entropy alloys makes them promising candidates for critical engineering applications in extreme service environments,particularly under combined hightempe...The extraordinary high-temperature strength of refractory high-entropy alloys makes them promising candidates for critical engineering applications in extreme service environments,particularly under combined hightemperature and high-strain rate loading conditions.This study investigated the coupling effects of temperature(293-1273 K)and strain rate(0.001-3000 s^(-1))on the mechanical behavior and deformation mechanisms of an equiatomic TiZrNbVTa refractory high-entropy alloy with a single body-centered cubic structure.The alloy exhibits an exceptional combination of strength and ductility within the selected temperature and strain rate ranges.Micro structural analysis reveals that multiple deformation mechanisms,including severe lattice distortion,kink band formation,stress-induced martensite transformation from body-centered cubic to the omega phase,and third-type strain aging,occur over the considered wide range of temperatures and strain rates.These mechanisms significantly enhance the strength-ductility performance of the alloy,particularly under extreme conditions.Third-type strain aging occurs at different strain rates,shifting to a higher temperature range as strain rate increases.Zr atoms act as"solute atoms"forming short-range clusters,thereby pinning moving dislocations.Finally,a deformation mechanism map is proposed,spanning a wide range of temperatures and strain rates.This study provides valuable insights into the design of refractory high-entropy alloys for extreme thermos-mechanical applications.展开更多
As a typical eutectic high-entropy alloy(EHEA),AlCoCrFeNi2.1 exhibits excellent casting properties.However,the imbalance between strength and plasticity hinders its application as an advanced structural material.In or...As a typical eutectic high-entropy alloy(EHEA),AlCoCrFeNi2.1 exhibits excellent casting properties.However,the imbalance between strength and plasticity hinders its application as an advanced structural material.In order to address this challenge,deep cryogenic treatment(DCT)as a new process applied in the field of EHEAs was proposed in this study.The effects of different DCT times on the microstructure and mechanical properties of AlCoCrFeNi2.1 EHEAs were studied,mainly focusing on the flake structure of FCC+B2 layer.The experimental results suggest that with the extension of the DCT time,the dislocation density in the FCC phase increases significantly.The spherical BCC precipitate phase is generated within the B2 phase,and the average size of this newly generated precipitate phase gradually decreases.Increasing the number of dislocations and precipitate phases is of great significance to improve the mechanical properties.The AlCoCrFeNi2.1 EHEA exhibits excellent comprehensive mechanical properties after DCT for 36 h.Compared with the as-cast state,the tensile strength at room temperature reaches 1,034.51 MPa,increased by 5.74%.The plasticity reaches 21.72%,which is increased by 11.79%.The results show that the tensile strength and ductility of AlCoCrFeNi2.1 EHEAs are balanced and improved after DCT,which are more suitable as advanced structural materials.In addition,the introduction of the DCT process to EHEAs solves the problem of environmental pollution caused by traditional heat treatment process.This study provides useful guidance for using the DCT process to strengthen the mechanical properties of“lamellar+block”type EHEAs.展开更多
In this study,FeCr_(x)MnAlCu(x=0,0.5,1.0,1.5,2.0)high-entropy alloys were fabricated using vacuum arc melting,and the corrosion behavior of these alloys in 3.5wt%NaCl solution at room temperature was investigated by e...In this study,FeCr_(x)MnAlCu(x=0,0.5,1.0,1.5,2.0)high-entropy alloys were fabricated using vacuum arc melting,and the corrosion behavior of these alloys in 3.5wt%NaCl solution at room temperature was investigated by electrochemical dynamic potential polarization curves and immersion experiments.The microstructure results show that the high-entropy alloy with x=0 has a body-centered cubic phase structure,whereas the high-entropy alloys with x=0.5–2.0 have a mixed face-centered cubic+body-centered cubic dual-phase structure.The corrosion results show that the corrosion resistance of the high-entropy alloy is increased with the increase in Cr content.Among them,the high-entropy alloy with x=2.0 exhibits the optimal corrosion resistance:the highest self-corrosion potential(E_(corr)=−0.354 V vs.Ag/AgCl),the smallest self-corrosion current density(I_(corr)=1.991×10^(−6)A·cm^(−2)),and the smallest corrosion rate(0.0292 mm/a).The composite passivation film of oxides and hydroxides is formed on the surface of the corroded high-entropy alloys,and the Cr_(2)O_(3)content is increased with the increase in Cr content,which effectively improves the stability and protective properties of the passivation film.展开更多
The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing t...The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.展开更多
High-entropy magnetocaloric alloys offer exceptional compositional flexibility and stability for magnetic refrigeration.However,enhancing their magnetic entropy change,working temperature range,and refrigeration capac...High-entropy magnetocaloric alloys offer exceptional compositional flexibility and stability for magnetic refrigeration.However,enhancing their magnetic entropy change,working temperature range,and refrigeration capacity remains challenging.In this study,we demonstrate that microalloying GdTbDyHo with only 0.4at%nonmagnetic Y effectively addresses this limitation.Our analysis indicates that Y uniformly dissolves into the hexagonal matrix lattice,disrupting the 4f–4f exchange interactions and inducing a local short-range order.This weakens the antiferromagnetic coupling,accelerates the antiferromagnetic–ferromagnetic transition,and broadensits range.Consequently,the peak magnetic entropy change increases from 8.2 to 8.7 J·kg^(−1)·K^(−1),the working temperature range expands from 77 to 89 K,and the refrigeration capacity improves by 23%,reaching 774 J·kg^(−1)(5 T)relative to the Y-free alloy,while the Néel temperature remains constant(~195 K).This study establishes nonmagnetic microalloying as a cost-effective and scalable strategy for designing high-performance magnetocaloric materials.展开更多
基金supported by the National Natural Science Foundation of China(52302240)the Macao Young Scholars Program(AM2023011)the Yuanguang Scholars Program,Hebei University of Technology(282022554)。
文摘Lithium-sulfur(Li-S)batteries are considered a potential candidate for next-generation energy-dense and sustainable energy storage.However,the slow conversion and severe shuttle of polysulfides(LiPSs)result in rapid performance degradation over long-term cycling.Herein,we report a high-entropy single-atom(HE-SA)catalyst to regulate the multi-step conversion of LiPS to attain a high-performance Li-S battery.Both the density functional theory calculations and the experimental results prove that the Fe atomic site with high spin configurations strongly interacts with Li_(2)S_(4)through d-p and s-p synergistic orbital hybridization which facilitates the reduction of LiPS.Moreover,S-dominant p-d hybridization between Li_(2)S and a high-spin Mn site weakens the Li-S bond and facilitates the rapid sulfur evolution reaction.Consequently,the Li-S battery with a bifunctional HE-SA catalyst shows an ultralow capacity decay of 0.026% per cycle over 1900 cycles at 1 C.This work proposes a high-entropy strategy for sculpting electronic structures to enable spin and orbital hybridization modulation in advanced catalysts toward longcycling Li-S batteries.
基金supported by the National Key R&D Program of China(2023YFA1507204)the National Natural Science Foundation of China(nos.22279030 and 52374301)+2 种基金the Natural Science Fund for Distinguished Young Scholars of Heilongjiang Province(No.JQ2024B003)the Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(no.HKDEFM2021201)the Fundamental Research Funds for the Undergraduate Universities of Heilongjiang Province(2024-KYYWF-0122)。
文摘High-entropy spinel oxides are promising anode materials for lithium-ion batteries owing to their unique crystal structures,which provide enhanced structural stability,multiple redox-active sites,and three-dimensional Li^(+)diffusion pathways.However,the intrinsic complexity and compositional diversity of high-entropy systems have limited a comprehensive understanding of the correlation between crystal structure,elemental composition,and rate performance,thereby impeding further optimization and practical application.
基金financially supported by the National Natural Science Foundation of China(No.52562006 and No.52502065)Yunnan Major Scientific and Technological Projects(No.202302AG050010)Yunnan Province Innovation Team(No.202305AS350018)
文摘The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conductivities of high-entropy ceramics(HECs).Although RE_(3)MO_(7) (RE represents rare-earth elements;M is Ta or Nb) ceramics have been widely studied for use in thermal barrier coatings and solid oxide fuel cells,their application scope can be broadened through the effective manipulation of the thermal/oxygen ionic conductivities.Herein,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))_(3)Ta_(1/2)Nb_(1/2)O_(7) HECs are designed and synthesized.These ceramics exhibit lower thermal conductivity and higher oxygen ionic conductivity than pristine ordered RE_(3)MO_(7) ceramics.Characterization results prove that high-entropy effects in the prepared material enhance atomic displacement parameters(ADPs),causing an increase in the oxygen ionic conductivity by a factor of 10 and enhancement in the phonon scattering rate,thereby reducing thermal conductivity by increasing ADPs.The ADPs can act as an indicator of the anharmonic vibration strength of the lattice,affecting the thermal/oxygen ionic conductivity and thermal expansion coefficient.Furthermore,in nano-indentation tests,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))3Ta_(1/2)Nb_(1/2)O_(7) HECs show high hardness(11.8 GPa),toughness(2.0 MPa·m^(1/2)),and modulus(215.0 GPa),which are beneficial for structural/functional applications.Overall,the obtained results indicate that thermal/oxygen ionic transport mechanisms can be used to further improve the properties and thereby expand the application scope of various HECs.
基金National Natural Science Foundation of China(51774179)Natural Science Foundation of Liaoning Province(20180550546)+2 种基金Joint Fund of State Key Laboratory of Metal Material for Marine Equipment and Application(HGSKL-USTLN(2021)03)High-Level Talent Fund of USTL(6003000377,6003000294)supported by Liaoning Provincial Department of Education(LJ212410146037)。
文摘The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.
基金Project supported by the Youth Program of the National Natural Science Foundation of China(Grant No.12405324)the CNNC Science Fund for Talented Young Scholars(Grant No.24940)the CNNC Basic Science Fund(Grant No.24851)。
文摘Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simulations to explore the CSRO effect on the generation and evolution behaviors of irradiation defects.The results demonstrate that CSRO can suppress the formation of Frenkel pairs in TiVTaNb HEAs,with the suppression effect becoming more pronounced as the degree of CSRO increases.CSRO can change the types of interstitial defects generated during cascade collisions.Specifically,as the degree of CSRO increases,the proportion of Ti-related interstitials shows a marked enhancement,primarily evidenced by a significant rise in Ti–Ti dumbbells accompanied by a corresponding decrease in Ti–V dumbbells.CSRO exhibits negligible influence on defect clustering and the nucleation and evolution of dislocation loops.Regardless of CSRO conditions,TiVTaNb HEAs preserve exceptional radiation tolerance throughout the cascade damage process,suggesting that the intrinsic properties of this multi-principal element system dominate its radiation response.These findings provide fundamental insights into the CSRO effect on defect formation and evolution behaviors in HEAs,which may provide new design strategies for high-entropy alloys.
基金National Science Foundation of China(Nos.52401212 and52401214)the National Science Foundation of Jiangsu Province(No.BK20241020)+1 种基金the Avi-ation Foundation(No.2023Z0530S6004)the Jiangsu Province University Collaborative Innovation Centre(High-Tech Ships)Pro-gram(No.XTCX202401).
文摘Refractory high-entropy alloys(RHEAs)are promising for high-temperature applications due to their ex-ceptional mechanical properties at high temperatures.However,limited studies on their high-temperature fatigue behavior hinder further development.This study systematically investigates the low-cycle fatigue(LCF)behavior of HfNbTiZr RHEA at room temperature(25℃)and elevated temperatures(350,450,and 600℃)through a combination of experimental analyses and dislocation-based damage-coupled crystal plasticity finite element(CPFE)simulations,to unveil the effects of creep damage on LCF behavior at varying temperatures.The results indicate that the LCF life dramatically decreases at an increased tem-perature,shifting from transgranular fatigue damage at lower temperatures(25-350℃)to a dual damage mechanism involving both intergranular fatigue and creep damage at higher temperatures(450-600℃).At 600℃,creep damage notably contributes to the accumulation of geometrically necessary dislocations(GNDs),crack initiation,and propagation at grain boundaries,and thus accelerates LCF failure.Compara-tive CPFE simulations reveal that creep damage significantly contributes to cyclic softening and reduction in elastic modulus,which also amplifies the strain localization under the LCF loading.The contribution of creep damage to the total stored energy density(SED)representing the overall damage increases with temperatures,accounting for 11%at 600℃.Additionally,CPFE simulations indicate that the creep dam-age notably influences the magnitude of GND density localized at grain boundaries.This study provides critical insights into the fatigue damage mechanisms of RHEAs,offering valuable guidance for their ap-plication in high temperatures.
基金supported by the Jiangxi Provincial Key Research and Development Program(No.20232BBE50007)the Jiangxi Provincial Natural Science Foundation(No.20224BAB214018).
文摘In the present study,AlCoCrFeNi_(2.1)eutectic high-entropy alloy(EHEA)has been fabricated by laser melting deposition(LMD).The influence of laser energy density on microstructures,wear resistance and corrosion resistance of the alloy was systematically explored.The results indicate that the AlCoCrFeNi_(2.1)EHEA exhibited lamellar eutectic microstructures with alternating FCC and BCC phases.With the increase in laser energy density,the alloy grain size,interlamellar spacing,and volume fraction of the FCC phase increased,while the hardness of the alloy decreased.Meanwhile,the tribological performance of the alloy deteriorated with increasing laser energy density,and the combined effects of abrasive wear and adhesive wear gradually became significant.In addition,increasing laser energy density from 18.2 to 25 J/mm^(2)resulted in the increase in corrosion current density of the AlCoCrFeNi_(2.1)EHEA from 6.36×10^(−8) to 3.02×10^(−7) A/cm^(2)and the negative shift of corrosion potential from−211 to−292 mV(SCE).In summary,reducing laser energy density improved the wear and corrosion performance of the additively manufactured AlCoCrFeNi_(2.1)EHEA.
基金National Natural Science Foundation of China(52201177)Hebei Province Department of Education Fund(QN2024264)Natural Science Foundation of Hebei Province(E2022201010)。
文摘Four machine learning algorithms were used to predict the solid solution phases of high-entropy alloys(HEAs).To improve the model accuracy,the K-fold cross validation was adopted.Results show that the K-nearest neighbor algorithm can effectively distinguish body-centered cubic(bcc)phase,face-centered cubic(fcc)phase,and mixed(fcc+bcc)phase,and the accuracy rate is approximately 93%.Thereafter,CoCrFeNi_(2)Al_(x)(x=0,0.1,0.3,1.0)HEAs were prepared and characterized by X-ray diffractometer and energy disperse spectrometer.It is found that their phases are transformed from fcc phase to fcc+bcc phase,which is consistent with the prediction results of machine learning.Furthermore,the influence of Al content on the microstructure and tribological properties of CoCrFeNi_(2)Al_(x)(x=0,0.1,0.3,1.0)HEAs was evaluated.Results reveal that with the increase in Al content,the nanohardness and microhardness increase by approximately 45%and 75%,respectively.The elastic limit parameter H/Er increases from 0.0216 to 0.030,whereas the plastic deformation resistance parameter H^(3)/E_(r)^(2) increases from 0.0014 to 0.0045,which demonstrates an improvement in nanohardness with the increase in Al addition amount.In addition,the wear rate decreases by 35%with the increase in Al addition amount.This research provides a new idea with energy-saving and time-reduction characteristics to prepare HEAs.
基金National Natural Science Foundation of China(52305349)Heilongjiang Touyan Team(HITTY-20190036)+2 种基金Heilongjiang Provincial Natural Science Foundation of China(LH2023E033)CGN-HIT Advanced Nuclear and New Energy Research Institute(CGN-HIT202305)Natural Science Basic Research Program of Shaanxi Province(2023-JC-QN-0518)。
文摘The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at current density of 60 A/mm^(2) and strain rate of 0.1 s^(−1),the ultimate tensile stress shows a significant decrease from approximately 3000 MPa to 1900 MPa with reduction ratio of about 36.7%.However,as current density increases,elongation decreases due to intermediate temperature embrittlement.This is because the current induces Joule effect,which then leads to stress concentration and more defect formation.Moreover,the flow stress is decreased with the increase in strain rate at constant current density.
基金National Natural Science Foundation of China(12404230,52061027)Science and Technology Program Project of Gansu Province(22YF7GA155)+1 种基金Lanzhou Youth Science and Technology Talent Innovation Project(2023-QN-91)Zhejiang Provincial Natural Science Foundation of China(LY23E010002)。
文摘(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.
基金financially supported by the Shanghai Science and Technology Plan Project(No.23ZR1467000)Basic Research Project of Tongji University(No.22120240354)+2 种基金State Key Laboratory of Treatments and Recycling for Organic Effluents by Adsorption in Petroleum,Chemical Industry(No.SDHY2206)National Natural Science Foundation of China(No.21976134)the Fundamental Research Funds for the Central Universities。
文摘Electrocatalytic reduction of nitrate to ammonia offers an environmentally friendly and sustainable approach for ammonia production,but it involves a multi-step reaction process with complex intermediates,and still faces the challenge of high activity and high selectivity.Herein,a high-entropy nanoalloy was synthesized via high-temperature annealing of metal salt with dopamine as a carbon source for electrocatalytic reduction of nitrate to ammonia.The FeCoNiCuRu_(1.5)/C catalyst displays a conversion rate of 90.2%and an ammonia selectivity of 92.2% at-0.74 V(vs.RHE),significantly surpassing the performance of lowentropy alloys such as FeCo/C by 1.5–2 times.Moreover,FeCoNiCuRu_(1.5)/C maintains a consistent nitrate conversion rate of about 90.0% after 120 h of continuous operation(10 cycles),indicating high stability.The superior performance of FeCoNiCuRu_(1.5)/C can be attributed to the synergetic relay catalysis among Fe,Co,Ni,Cu,and Ru sites.This synergy enhances nitrate adsorption due to the optimized electronic structure of multiple active sites,which facilitates the nitrate reduction to intermediates.Subsequently,the effective active hydrogen produced at the Ru site,in conjunction with adjustments at other metal sites,promotes the selective transformation of the intermediates into ammonia.This work not only highlights the efficacy of synergetic relay electrocatalysis but also opens new avenues for developing highly efficient multi-site catalysts.
基金supported by the National Natural Science Foundation of China(Grant No.12405324)the CNNC Science Fund for Talented Young Scholars,the Dean’s Fund of China Institute of Atomic Energy(Grant No.219256)the Director’s Fund of China Institute of Atomic Energy(Grant No.218296).
文摘Creep is an important mechanical property of refractory high-entropy alloys(RHEAs)at high temperatures.The existence of short-range order(SRO)and its ability to improve the strength or plasticity of high-entropy alloys(HEAs)have been experimentally proven.However,there is still little research on the correlation between SRO and creep behavior.The mechanism of SRO influencing creep behavior is not yet clear.In this work,the creep behaviors of TiVTaNb RHEA with and without SRO were simulated at various temperatures and stresses using molecular dynamics methods,and the effects of SRO on creep behavior were analyzed.The results show that the SRO is energetically favorable for occurrence in this RHEA.For polycrystalline RHEAs,grain boundary energy is an important driving force for the formation of SRO.Significantly,under the same conditions,the SRO can reduce the steady-state creep rate and change the creep mechanism of the RHEA.Specifically,the models with SRO will exhibit lower stress exponent and grain-size exponent.A mechanism by which SRO reduces the effects of grain boundaries on creep has been discovered.These phenomena can be well explained by the effects of SRO on atomic diffusion.In addition,by analyzing the diffusion ability of different elements,SRO can induce localization of atomic diffusion,resulting in strain localization under high stresses.This work highlights the importance of SRO on the creep of RHEAs and provides a reference for establishing a reasonable creep model of RHEAs.
基金supported by the China Scholarship Council(No.202208210253)the Natural Science Foundation of Liaoning Province(2022-MS-272)the Scientific Research Funding Project of the Education Department of Liaoning Province(LJKMZ20220463).
文摘Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and wear properties of Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were systematically investigated.Al_(0.5)CrFeNi_(2.5)HEA exhibits a face-centered cubic(FCC)matrix with Ni3Al-type ordered nanoprecipitates.When Si was doped,σphase and Cr-rich nanoprecipitates existed in the B2 matrix and L12 in the FCC matrix.The nanohardness was increased from 4.67 to 5.45 GPa with doping of Si,which is associated with forming the new phases and improved nanohardness of L12/FCC phases.The coefficient of friction(COF)value was reduced from 0.75 to 0.67 by adding Si.σphase and Cr-rich nanoprecipitates in B2 matrix support a decreased wear rate from 7.87×10^(-4) to 6.82×10^(-4) mm^(3)/(N m).Furthermore,the main wear mechanism of Al_(0.5)CrFeNi_(2.5)and Al_(0.5)CrFeNi_(2.5)Si0.25 HEAs is abrasive wear.
基金the Ahvaz Branch, Islamic Azad University for the financial support
文摘FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)affected the microstructures of the thin films and their mechanical and corrosion properties.Compared with the FeCoCrMnNi thin films with 1-sccm N_(2),the addition of 2 and 3 sccm of N_(2)by as much as 5.45at%and 6.34at%changed the solid solution’s crystalline structure into an amorphous structure.The addition of nitro-gen caused drastic changes to the surface morphology,creating a smoother and more uniform surface without cauliflower units.The atomic force microscopy image analysis indicated that the addition of nitrogen reduced the surface roughness from 5.58 to 1.82 nm.Adding N_(2)to the CoCrFeMnNi thin film helped increase its mechanical properties,such as hardness and strength,while the Young’s modulus decreased.The hardness of(8.75±0.5)GPa and the reduced Young’s modulus of(257.37±11.4)GPa of the FeCoCrMnNi thin film reached(12.67±1.2)and(194.39±12.4)GPa,respectively,with 1 sccm N_(2).The applied coating of the CoCrFeMnNi thin film on 304SUS increased the corrosion resistance,whereas the addition of nitrogen to the CoCrFeMnNi thin film also improved its corrosion res-istance compared with that of the CoCrFeMnNi thin film without nitrogen.
基金financially supported by the Natural Science Foundation of Shaanxi Province(No.2021JZ-53)the Program for Graduate Innovation Fund of Xi'an Shiyou University(No.YCS22213146).
文摘The short-range ordering(SRO)structure has been considered as a toughening method to improve the mechanical properties of high-entropy alloys(HEAs).However,the strengthening mechanism of the SRO structures on the HEAs still needs to be further revealed.Here,the effect of element distribution,Al content,crack orientation,temperature,and strain rate on the crack propagation behavior of the AlxFeCoCrNi HEAs are investigated using Monte Carlo(MC)/molecular dynamics(MD)simulation methods.Two HEA models are considered,one with five elements randomly distributed in the alloys,i.e.RSS_HEAs,and the other presenting SRO structure in the alloys,namely SRO_HEAs.The results show that Al atoms play a decisive role in the SRO degree of the HEA.The higher the Al content,the greater the SRO degree of the HEA,and the stronger the resistance of the SRO structure to crack propagation in the alloys.The results indicate that the reinforcement effect of the SRO structure in the model with the(111)[110]crack is more significant than that with the(111)[110]crack.The results show that the crack length of the alloys at maximum strain does not monotonically increase with temperature,but rather exhibits a turning point at the temperature of 400 K.When the temperature is below 400 K,the crack length of the alloys increases with the increase of temperature,while above 400 K,the opposite trend appears.In addition,the results indicate that the crack length of the alloys decreases with increasing strain rate under the same strain.
基金financially supported by the National Natural Science Foundation of China(Nos.12172245,12225207,and 12372364)
文摘The extraordinary high-temperature strength of refractory high-entropy alloys makes them promising candidates for critical engineering applications in extreme service environments,particularly under combined hightemperature and high-strain rate loading conditions.This study investigated the coupling effects of temperature(293-1273 K)and strain rate(0.001-3000 s^(-1))on the mechanical behavior and deformation mechanisms of an equiatomic TiZrNbVTa refractory high-entropy alloy with a single body-centered cubic structure.The alloy exhibits an exceptional combination of strength and ductility within the selected temperature and strain rate ranges.Micro structural analysis reveals that multiple deformation mechanisms,including severe lattice distortion,kink band formation,stress-induced martensite transformation from body-centered cubic to the omega phase,and third-type strain aging,occur over the considered wide range of temperatures and strain rates.These mechanisms significantly enhance the strength-ductility performance of the alloy,particularly under extreme conditions.Third-type strain aging occurs at different strain rates,shifting to a higher temperature range as strain rate increases.Zr atoms act as"solute atoms"forming short-range clusters,thereby pinning moving dislocations.Finally,a deformation mechanism map is proposed,spanning a wide range of temperatures and strain rates.This study provides valuable insights into the design of refractory high-entropy alloys for extreme thermos-mechanical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52301061,52204394)the Joint Fund Project of Science and Technology Plan of Liaoning Province(No.2023-MSLH-250)the Science and the Technology Program of Liaoning Provincial Department of Education(No.JYTQN2023286)。
文摘As a typical eutectic high-entropy alloy(EHEA),AlCoCrFeNi2.1 exhibits excellent casting properties.However,the imbalance between strength and plasticity hinders its application as an advanced structural material.In order to address this challenge,deep cryogenic treatment(DCT)as a new process applied in the field of EHEAs was proposed in this study.The effects of different DCT times on the microstructure and mechanical properties of AlCoCrFeNi2.1 EHEAs were studied,mainly focusing on the flake structure of FCC+B2 layer.The experimental results suggest that with the extension of the DCT time,the dislocation density in the FCC phase increases significantly.The spherical BCC precipitate phase is generated within the B2 phase,and the average size of this newly generated precipitate phase gradually decreases.Increasing the number of dislocations and precipitate phases is of great significance to improve the mechanical properties.The AlCoCrFeNi2.1 EHEA exhibits excellent comprehensive mechanical properties after DCT for 36 h.Compared with the as-cast state,the tensile strength at room temperature reaches 1,034.51 MPa,increased by 5.74%.The plasticity reaches 21.72%,which is increased by 11.79%.The results show that the tensile strength and ductility of AlCoCrFeNi2.1 EHEAs are balanced and improved after DCT,which are more suitable as advanced structural materials.In addition,the introduction of the DCT process to EHEAs solves the problem of environmental pollution caused by traditional heat treatment process.This study provides useful guidance for using the DCT process to strengthen the mechanical properties of“lamellar+block”type EHEAs.
基金Gansu Provincial Science and Technology Major Special Program(24ZDWA008)Fourth Batch of Top Leading Talents Fund Projects in Gansu Province(ZZ2023G50100013)。
文摘In this study,FeCr_(x)MnAlCu(x=0,0.5,1.0,1.5,2.0)high-entropy alloys were fabricated using vacuum arc melting,and the corrosion behavior of these alloys in 3.5wt%NaCl solution at room temperature was investigated by electrochemical dynamic potential polarization curves and immersion experiments.The microstructure results show that the high-entropy alloy with x=0 has a body-centered cubic phase structure,whereas the high-entropy alloys with x=0.5–2.0 have a mixed face-centered cubic+body-centered cubic dual-phase structure.The corrosion results show that the corrosion resistance of the high-entropy alloy is increased with the increase in Cr content.Among them,the high-entropy alloy with x=2.0 exhibits the optimal corrosion resistance:the highest self-corrosion potential(E_(corr)=−0.354 V vs.Ag/AgCl),the smallest self-corrosion current density(I_(corr)=1.991×10^(−6)A·cm^(−2)),and the smallest corrosion rate(0.0292 mm/a).The composite passivation film of oxides and hydroxides is formed on the surface of the corroded high-entropy alloys,and the Cr_(2)O_(3)content is increased with the increase in Cr content,which effectively improves the stability and protective properties of the passivation film.
基金National Key R&D Program of China(2023YFB3711904,2022YFA1603801)National Natural Science Foundation of China(12404230,52471181,52301213,52130108,52471005)+2 种基金National Nature Science Foundation of Zhejiang Province(LY23E010002)Open Fund of the China Spallation Neutron Source,Songshan Lake Science City(KFKT2023B11)Guangdong Basic and Applied Basic Research Foundation(2022A1515110805,2024A1515010878)。
文摘The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.
基金financially supported by the National Sci-ence Foundation for Young Scientists of China(Nos.52201172,52201171,52401219)the National Science Fund for Distinguished Young Scholars(No.52225103)+4 种基金the National Natural Science Foundation of China(No.52130108)the National Key R&D Program of China(No.2022YFB4602101)the Joint Funds of the National Natural Science Foundation of China(No.U2441262)the Funds for International Cooperation and Exchange of the National Nat-ural Science Foundation of China(No.W2412068)the Fundamental Research Fund for the Central Universities of China(No.FRF-TP-22-001C2).
文摘High-entropy magnetocaloric alloys offer exceptional compositional flexibility and stability for magnetic refrigeration.However,enhancing their magnetic entropy change,working temperature range,and refrigeration capacity remains challenging.In this study,we demonstrate that microalloying GdTbDyHo with only 0.4at%nonmagnetic Y effectively addresses this limitation.Our analysis indicates that Y uniformly dissolves into the hexagonal matrix lattice,disrupting the 4f–4f exchange interactions and inducing a local short-range order.This weakens the antiferromagnetic coupling,accelerates the antiferromagnetic–ferromagnetic transition,and broadensits range.Consequently,the peak magnetic entropy change increases from 8.2 to 8.7 J·kg^(−1)·K^(−1),the working temperature range expands from 77 to 89 K,and the refrigeration capacity improves by 23%,reaching 774 J·kg^(−1)(5 T)relative to the Y-free alloy,while the Néel temperature remains constant(~195 K).This study establishes nonmagnetic microalloying as a cost-effective and scalable strategy for designing high-performance magnetocaloric materials.
