A chemical composite plating of Ni-B_(4)C was used to prepare the surface-modified zirconia toughened alumina(ZTA)ceramic particles.The ceramic preforms were prepared by the plated ZTA and sodium silicate solution bin...A chemical composite plating of Ni-B_(4)C was used to prepare the surface-modified zirconia toughened alumina(ZTA)ceramic particles.The ceramic preforms were prepared by the plated ZTA and sodium silicate solution binder,followed by casting infiltration to prepare the ZTA particles reinforced high chromium cast iron(HCCI)composites.The result reveals that a distinct interface layer forms at the ZTA/HCCI interface,which consists of phases of ZrB_(2),FeB,Fe_(2)B,and NaSiO_(4).The interfacial wettability between ZTA and HCCI is improved by the diffusion and reaction of Ni and B_(4)C.The wear test reveals that the Ni-B_(4)C plated ZTA particles can effectively improve the wear resistance of the ZTA/HCCI composite,and the wear rate of the composite is decreased to 11.6%of HCCI.展开更多
Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufac...Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.展开更多
Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a seri...Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.展开更多
Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusio...Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.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
Sodium salts of mono-and di-carboxylic acids(glycolic,fumaric and benzoic acid)were studied as corrosion inhibitors for AM50 alloy in pH neutral aqueous NaCl environment.Hydrogen evolution,electrochemical and surface ...Sodium salts of mono-and di-carboxylic acids(glycolic,fumaric and benzoic acid)were studied as corrosion inhibitors for AM50 alloy in pH neutral aqueous NaCl environment.Hydrogen evolution,electrochemical and surface characterization techniques were employed to reveal their corrosion inhibition mechanism,whilst the molecular features of inhibitors were investigated by quantum chemical calculation.All inhibitors reduced anodic dissolution of AM50 and their efficiency generally increased with time and concentration from 5 mM to 100 mM.The inhibition mechanism can be described as physisorption of inhibitive molecules on the surface of the intrinsic oxide layer followed by chemisorption with Mg^(2+)and Al^(3+),and the difference in inhibition action among these inhibitors was explained on the molecular scale.展开更多
A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness.The comprehensive mechanical properties of magnesium alloys have su...A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness.The comprehensive mechanical properties of magnesium alloys have supported the expansion of their applications in the automotive,aerospace,and biomedical industries.Herein,pre-treatment of a solution-treated Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was conducted to investigate the precipitate behavior and microstructure evolution during the ECAP process.β;phase grains quickly precipitated from the solution-treated alloy,which accelerated grain refinement and enhanced the ductility after the ECAP process,as compared to the as-cast alloy reported in our previous study.Moreover,spherical precipitates (~200 nm) and fine phases (~100 nm) precipitated along the stripe-like Zn;Zr;phase,which formed a kabap-like structure dispersing homogeneously in the solution-treated alloy during the ECAP process.Owing to grain refinement,dislocations,sphericalβ;precipitates,and texture evolution,the solution-treated alloy after eight passes of ECAP exhibited good comprehensive mechanical properties,with the ultimate tensile strength,yield strength,and elongation values reaching210.9 MPa,263.9 MPa,and 27.9%,respectively.展开更多
Although magnesium(Mg)and its alloys are proposed as the next generation orthopedics transplanted materials,their clinical applications are limited by the fast degradation.To reduce the degradation rate,a strong adhes...Although magnesium(Mg)and its alloys are proposed as the next generation orthopedics transplanted materials,their clinical applications are limited by the fast degradation.To reduce the degradation rate,a strong adhesion poly-dopamine(PDA)layer was introduced as an intermediate layer for the subsequent alginate(ALG)spin-coating on high-purity Mg.The surface morphology and chemical composition were detected by scanning electron microscope,energy disperse spectroscopy,and Fourier transform infrared spectroscopy.The corrosion resistances of all samples were evaluated by electrochemical and 10-day immersion tests in Hanks’balanced salt solution.Our results suggest that the thickness of the fabricated PDA/ALG composite coating is 8.58±0.65μm,and the intermediate PDA layer evidently enhances the adhesion between the substrate and ALG coating.The corrosion current density of Mg coated with the PDA/ALG composite coating decreases more than 10 times compared to that of the Mg substrate,and the charge transfer resistance is 12 times bigger than that of the bare Mg,which indicates the improved corrosion resistance.Moreover,the mechanism of corrosion protection of the composite coating is also discussed.展开更多
The severely worn position and failure mechanisms of the ring die of a feed pellet machine were investigated.The macroscopic and microscopic morphologies of the failed surface,the chemical composition and mechanical p...The severely worn position and failure mechanisms of the ring die of a feed pellet machine were investigated.The macroscopic and microscopic morphologies of the failed surface,the chemical composition and mechanical properties of the collected samples were analyzed using scanning electron microscopy,energy disperse spectroscopy,optical emission spectrometry,and a universal testing machine.Results show that the dip angle at the entrance of the ring die hole between the roller and ring die was severely worn.The feed powder could not be fully extruded through the dip angle at the entrance of the ring die holes,thus the density of the feed particles produced could not meet the requirements.Therefore,abrasive wear under high stress is the main reason of failure at the entrance of the ring die holes under the action of feeding powder;and cutting and fatigue spalling lead to substantial material loss.In addition,a high damp-heat environment aggravates abrasive wear on the die hole internal surface.展开更多
Magnesium(Mg)alloys are attractive biodegradable implant materials.The degradation products on Mg alloys play a critical role in the stability of the interface between implant and surrounding tissue.In the present stu...Magnesium(Mg)alloys are attractive biodegradable implant materials.The degradation products on Mg alloys play a critical role in the stability of the interface between implant and surrounding tissue.In the present study,the effects of dynamic deformation on the interface layer of biomedical Mg-1Zn alloy were investigated using the constant extension rate tensile tests(CERT)coupled with electrochemical impedance spectroscopy(EIS).The deformation of the Mg-1Zn alloy had an adverse influence on the impedance of the surface degradation layer formed in simulated body fluid that only containing inorganic compounds.However,the surface degradation layer with improved corrosion resistance was obtained for the strained samples tested in protein-containing simulated body fluid.The spontaneous or enhanced adsorption of protein into the degradation product led to a flexible and stable hybrid anti-corrosive layer.A relationship between the dynamic deformation of Mg alloy and the impendence of the degradation layer was established,which demonstrates the necessity for in situ characterisation of the evolution of the surface layer under dynamic condition.展开更多
Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation...Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation and dehydrogenation of this group of materials.Severe plastic deformation(SPD)methods,such as equal-channel angular pressing(ECAP),high-pressure torsion(HPT),intensive rolling,and fast forging,have been widely used to enhance the activation,air resistance,and hydrogenation/dehydrogenation kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects.These severely deformed materials,particularly in the presence of alloying additives or second-phase nanoparticles,can show not only fast hydrogen absorption/desorption kinetics but also good cycling stability.It was shown that some materials that are apparently inert to hydrogen can absorb hydrogen after SPD processing.Moreover,the SPD methods were effectively used for hydrogen binding-energy engineering and synthesizing new magnesium alloys with low thermodynamic stability for reversible low/room-temperature hydrogen storage,such as nanoglasses,high-entropy alloys,and metastable phases including the high-pressureγ-MgH2 polymorph.This work reviews recent advances in the development of Mg-based hydrogen storage materials by SPD processing and discusses their potential in future applications.展开更多
High corrosion resistance of alloys is essential for their structural applications;however,most alloys suffer from degradation of their corrosion resistance with the increasing acidity of their surround-ings.Nonethele...High corrosion resistance of alloys is essential for their structural applications;however,most alloys suffer from degradation of their corrosion resistance with the increasing acidity of their surround-ings.Nonetheless,we developed a series of medium-entropy alloys(MEAs)in this work,which ex-hibit high strength,superior fracture toughness and ultra-high corrosion resistance,outperforming the variety of corrosion resistant alloys hitherto reported.Most interestingly,our MEAs exhibit an unusual anti-corrosion behavior and their corrosion resistance increases with acidity in Cl−containing solutions.Through extensive thermodynamic calculations,density functional theory(DFT)simulations and experi-ments,we reveal that the unusual anti-corrosion behavior of our MEAs can be attributed to their surface chemical complexity,which facilitates the physio-chemical-absorption of H_(2)O and O_(2)and thus the rapid formation of metastable medium entropy passive films that contain the lowest amount of defects,as compared to the passive films on conventional alloys reported in the literature.展开更多
To realize economical and effective removal of hazardous 4-nitrophenol from the environment,we developed an easily recyclable ZnO nanowire array decorated with Cu nanoparticles.Its salix argyracea-shaped structure not...To realize economical and effective removal of hazardous 4-nitrophenol from the environment,we developed an easily recyclable ZnO nanowire array decorated with Cu nanoparticles.Its salix argyracea-shaped structure not only provides a platform to achieve stable and good dispersion of Cu nanoparticles,but also offers a great deal of catalytically active sites.The density functional theory calculations reveal that ZnO and Cu have a very beneficial synergistic effect on their catalytic capability.This synergy is ascribed to the electronic localization occurring at ZnO/Cu interface,which helps improve Cu nanoparticle’s ability to adsorb electro-negatively 4-nitrophenolate ions and to capture hydrogen radicals,thereby accelerating the hydrogen transfer from metal hydride complex to 4-nitrophenol.Benefiting from these characteristics,it exhibits high efficiency and reusability towards the catalytic reduction of waste 4-nitrophenol to valuable 4-aminophenol with a rate constant of 43.02×10^(-3)s^(-1)and an average conversion of 96.5%in 90 s during 10 cycles.This activity is superior to that of most reported noble-or non-noble-metal powder,bulk,coating,and array catalysts,indicating its competitive advantages in cost and efficiency,as well as enticing application prospects.展开更多
The wear interaction of cementite and pearlite in the white cast iron(WCI)was investigated using the two-body abrasive wear test under contact loads of 20,35,and 50 N.The wear behavior,wear surface morphology,sub-surf...The wear interaction of cementite and pearlite in the white cast iron(WCI)was investigated using the two-body abrasive wear test under contact loads of 20,35,and 50 N.The wear behavior,wear surface morphology,sub-surface structure,and wear resistance were evaluated using X-ray diffraction,microhardness testing,and nano-indentation.The results indicated that when the Cr content was increased from 0 to 4 wt%,there was a significant increase in the microhardness(H)and elasticity modulus(E)of the cementite.This yielded a 15.91%-and 23.6%-reduction in the degree of wear resistance and surface roughness,respectively.Moreover,no spalling and breaking of cementite was observed with increasing Cr content during the wear process,indicating improved wear resistance of the bulk cementite.In addition,the hard phase(cementite)and tough matrix(pearlite)composite structure exhibited a good protective and supporting effect.Thus,it was concluded that the interaction mechanism of the wear phase contributed to the reduction of the wear weight loss of the composite during the wear process.The contribution of the interaction between the hard wear-resistant phase and the tough phase in WCI to the wear resistance decreased with increasing hardness of the pearlite matrix.展开更多
High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure.HEAs are constructed with five or more principal alloying elements in equimolar or...High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure.HEAs are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios.Therefore,they can derive their performance from multiple principal elements ratherthan a single element.In this work,three-dimensional printing laser cladding was applied to produce an Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) HEA coating.The experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 μm in thickness.In the high-temperature laser cladding process,some Fe elements diffused from the substrate to the coating,forming a combination of face-centred cubic and body-centred cubic phase structures.The HEA coating metallurgically bonded well with the substrate.Owing to the increased dislocation density and number of grain boundaries,the HEA coating was harder and had a stronger hydrophobicity than X70 steel.The electrochemistry results showed that the HEA coating had better corrosion resistance than X70 steel.Aluminium oxides formed on the surface of the HEA coating had a certain protective effect.However,because of the laser cladding,the HEA coating generated cracks.In future work,the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks.展开更多
By a combination of the nanoindentation and electron probe microanalysis(EPMA)techniques,the traditional diffusion couple technique is extended to map the mechanical property of β-type Ti alloys over a wide compositi...By a combination of the nanoindentation and electron probe microanalysis(EPMA)techniques,the traditional diffusion couple technique is extended to map the mechanical property of β-type Ti alloys over a wide composition range,which can be utilized to develop very versatile novel bio-Ti alloys for hard tissue re placements in arti ficial bones,joints,and dental implants.To create complete single-phase composition ranges of Ti-based bcc solid solution,12 types of bcc Ti-Nb-Zr-Mo/Ti-Nb-Zr-Ta quaternary diffusion couples were fabricated and annealed at 1273 K for 25 h.In this way,the composition-mechanical property relationships in the vast composition space of Ti-based alloys were established using EPMA and nanoindentation probes.Notably,the measured composition-dependent Young’s moduli,hardness,and elastic recovery as well as the derived ratio of hardness to Young’s modulus,and the ratio of the cube of hardness to the square of Young’s modulus,in the developed compositional mechanical property database,were visualized in a five-dimensional scatter plot.This enables an effective tool to screen the Ti-Nb-Zr-based alloys fororthopedic and dental applications according to different clinical requirements,and to rationalize the fundamental mechanical relationships in the rapid development of β-Ti alloys.展开更多
Here,superhydrophobic cuprous oxide(Cu2O)with hierarchical micro/nanosized structures was synthesized via sprayassisted layer by layer assembling.The asprepared superhydrophobic meshes with high contact angle(159.6...Here,superhydrophobic cuprous oxide(Cu2O)with hierarchical micro/nanosized structures was synthesized via sprayassisted layer by layer assembling.The asprepared superhydrophobic meshes with high contact angle(159.6°)and low sliding angle(1°)are covered with Cu_(2)O "coral reef"like micro/nanosized structures.Interestingly,the superhydrophobic mesh surfaces became superhydrophilic again due to the oxidization of Cu_(2)O to CuO by annealing at a higher temperature(300℃).And the superhydrophobic properties would be recovered by heating at 120℃.Furthermore,the superwetting meshes were applied to design a miniature device to separate light or heavy oil from the wateroil mixtures with excellent separation efficiency.These superwetting surfaces by simultaneously sprayassisted layer by layer assembling technique show the potential application in universal oilwater separation.展开更多
High-temperature tribology,which is often involved during hot metal forming,is controlled via oxidation on a rubbing surface.However,for high chromium stainless steel(ST),where oxidation is strongly inhibited,the effe...High-temperature tribology,which is often involved during hot metal forming,is controlled via oxidation on a rubbing surface.However,for high chromium stainless steel(ST),where oxidation is strongly inhibited,the effect of counterface materials on tribological behavior is yet to be elucidated.In this study,the effects of counterfaces on the tribological behavior of 253MA ST and mild steel(MS)are investigated via a ball-on-disc test at 900°C using a 20 N load.The results reveal that high-speed steel(HSS)experiences severe abrasive wear with MS and causes severe sticking problems with ST.Si3N4 and SiC present substantially stronger abrasive wear resistance than HSS with MS,and the friction coefficients are dependent on the type of ceramic.Both ceramics can facilitate the establishment of a thick tribo-oxide layer(>3μm)on ST to prevent sticking;however,this is accompanied by severe pull-out and fracture wear.The effects of the counterface on the mechanical properties of the tribo-oxide layer,near-surface transformation,and the responses of the tribo-oxide layer to friction and wear are discussed.This study contributes to the understanding of interfacial tribological behaviors when different types of tools are used on MS and ST.展开更多
The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of m...The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.展开更多
Dendrites are the most common microstructural features in the cast metals,significantly affecting the structure integrity and mechanical properties of the castings.In this study,the in situ synchrotron X-ray radiograp...Dendrites are the most common microstructural features in the cast metals,significantly affecting the structure integrity and mechanical properties of the castings.In this study,the in situ synchrotron X-ray radiographic and tomographic imaging techniques were combined to evaluate the critical fracture stress of the growing dendrite tip during the solidification of an Al-15 wt%Cu alloy under an external electromagnetic force.Two dendritic 3D models have been proposed to simulate the dendrite 3D morphologic characteristics and thus revealed that the critical fracture stresses of the Al dendrites at temperatures close to its melting point were in the range of 0.5 kPa–0.05 MPa.The present results demonstrate the feasibility of measuring the high-temperature mechanical properties of the metallic dendrites.展开更多
基金financially supported by the National Natural Science Foundation of China(52005217)the University Research Platform and Research Projects of Guangdong Education Department(2022ZDZX3003)+2 种基金Basic and Applied Basic Research Fund Project of Guangdong Province in China(2022A1515010091,2021A1515010523,and 2020A1515110020)Basic Scientific Research Projects of Central Universities(No.21620344)Jinan University Open Fund for Advanced Materials(JNIWRM2021004)。
文摘A chemical composite plating of Ni-B_(4)C was used to prepare the surface-modified zirconia toughened alumina(ZTA)ceramic particles.The ceramic preforms were prepared by the plated ZTA and sodium silicate solution binder,followed by casting infiltration to prepare the ZTA particles reinforced high chromium cast iron(HCCI)composites.The result reveals that a distinct interface layer forms at the ZTA/HCCI interface,which consists of phases of ZrB_(2),FeB,Fe_(2)B,and NaSiO_(4).The interfacial wettability between ZTA and HCCI is improved by the diffusion and reaction of Ni and B_(4)C.The wear test reveals that the Ni-B_(4)C plated ZTA particles can effectively improve the wear resistance of the ZTA/HCCI composite,and the wear rate of the composite is decreased to 11.6%of HCCI.
基金the financial support by National Key Research and Development Project(Grand No.2020YFC1107202)Guangdong Basic and Applied Basic Research Foundation(Grand No.2020A1515110754)+3 种基金MOE Key Lab of Disaster Forest and Control in Engineering,Jinan University(Grand No.20200904008)Educational Commission of Guangdong Province(Grand No.2020KTSCX012)the Fundamental Research Funds for Central Universities(Grand No.21620342)the support from National Natural Science Foundation of China,NSFC(Grand No.51775556)。
文摘Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.
基金financially supported by the Young Scientists Fund of the National Natural Science Foundation of China(Nos.52104395 and 52304365)the Science and Technology Planning Project of Guangzhou,China(Nos.202102021080 and 2024A04J10006)+1 种基金the National Key R&D Program of China(No.2021YFC2902605)the Natural Science Foundation of Guangdong Province,China(Nos.2023A1515030145 and 2023A1515011847)。
文摘Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.
基金This work was financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120078,2021A1515111140,and 2021B1515120059)National Key Research and Development Project of China(No.2020YFC1107202)+3 种基金Science Research Cultivation Program(PY2022002)Science and Technology Planning Project of Guangzhou(No.202206010030)City University of Hong Kong Donation Research Grants[DONRMG No.9229021 and 9220061]as well as City University of Hong Kong Strategic Research Grant[SRG 7005505].
文摘Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.
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the financial support by Guangdong Basic and Applied Basic Research Founding (Grand No. 2020A1515110754)MOE Key Lab of Disaster Forest and Control in Engineering, Jinan University (Grand No. 20200904008)+4 种基金Educational Commission of Guangdong Province (Grand No. 2020KTSCX012)the Fundamental Research Funds for Central Universities (Grand No. 21620342)the High Performance Public Computing Service Platform of Jinan Universitythe financial support from National Natural Science Foundation of China (Grand No. 52071067)the Fundamental Research Funds for the Central Universities (Grand No. N2002009)。
文摘Sodium salts of mono-and di-carboxylic acids(glycolic,fumaric and benzoic acid)were studied as corrosion inhibitors for AM50 alloy in pH neutral aqueous NaCl environment.Hydrogen evolution,electrochemical and surface characterization techniques were employed to reveal their corrosion inhibition mechanism,whilst the molecular features of inhibitors were investigated by quantum chemical calculation.All inhibitors reduced anodic dissolution of AM50 and their efficiency generally increased with time and concentration from 5 mM to 100 mM.The inhibition mechanism can be described as physisorption of inhibitive molecules on the surface of the intrinsic oxide layer followed by chemisorption with Mg^(2+)and Al^(3+),and the difference in inhibition action among these inhibitors was explained on the molecular scale.
基金financially supported by the Regional Joint Youth Fund Project of Guangdong Basic and Applied Basic Research(Grant No.2020A1515110619)Guangzhou Science and Technology Plan Project(Grant No.202002030356)+1 种基金the 2019 Youth Innovative Talents Project of General Colleges and Universities in Guangdong Province(Grant No.2019KQNCX106)the Talent Cultivation Project of Guangzhou University(Grant No.RP2020126)。
文摘A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness.The comprehensive mechanical properties of magnesium alloys have supported the expansion of their applications in the automotive,aerospace,and biomedical industries.Herein,pre-treatment of a solution-treated Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was conducted to investigate the precipitate behavior and microstructure evolution during the ECAP process.β;phase grains quickly precipitated from the solution-treated alloy,which accelerated grain refinement and enhanced the ductility after the ECAP process,as compared to the as-cast alloy reported in our previous study.Moreover,spherical precipitates (~200 nm) and fine phases (~100 nm) precipitated along the stripe-like Zn;Zr;phase,which formed a kabap-like structure dispersing homogeneously in the solution-treated alloy during the ECAP process.Owing to grain refinement,dislocations,sphericalβ;precipitates,and texture evolution,the solution-treated alloy after eight passes of ECAP exhibited good comprehensive mechanical properties,with the ultimate tensile strength,yield strength,and elongation values reaching210.9 MPa,263.9 MPa,and 27.9%,respectively.
基金financially supported by National Key Research and Development Project of China(No.2020YFC1107202)Shanxi Provincial Key Research and Development Project(No.2019ZDLSF03–06)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120078)Science and Technology Planning Project of Guangdong Province(No.2021A0505030042)。
文摘Although magnesium(Mg)and its alloys are proposed as the next generation orthopedics transplanted materials,their clinical applications are limited by the fast degradation.To reduce the degradation rate,a strong adhesion poly-dopamine(PDA)layer was introduced as an intermediate layer for the subsequent alginate(ALG)spin-coating on high-purity Mg.The surface morphology and chemical composition were detected by scanning electron microscope,energy disperse spectroscopy,and Fourier transform infrared spectroscopy.The corrosion resistances of all samples were evaluated by electrochemical and 10-day immersion tests in Hanks’balanced salt solution.Our results suggest that the thickness of the fabricated PDA/ALG composite coating is 8.58±0.65μm,and the intermediate PDA layer evidently enhances the adhesion between the substrate and ALG coating.The corrosion current density of Mg coated with the PDA/ALG composite coating decreases more than 10 times compared to that of the Mg substrate,and the charge transfer resistance is 12 times bigger than that of the bare Mg,which indicates the improved corrosion resistance.Moreover,the mechanism of corrosion protection of the composite coating is also discussed.
基金financially supported by the National Key R&D Program of China(Grant No.:2017YFB0305100)the Teaching Quality and Teaching Reform Project of Guangdong Undergraduate Colleges and Universities:Construction Project of Experiment Demonstration Center(Grant No.:2017002)the Innovation Cultivation Project of Zhuhai College of Jilin University(Grant No.:2018XJCQSQ057)。
文摘The severely worn position and failure mechanisms of the ring die of a feed pellet machine were investigated.The macroscopic and microscopic morphologies of the failed surface,the chemical composition and mechanical properties of the collected samples were analyzed using scanning electron microscopy,energy disperse spectroscopy,optical emission spectrometry,and a universal testing machine.Results show that the dip angle at the entrance of the ring die hole between the roller and ring die was severely worn.The feed powder could not be fully extruded through the dip angle at the entrance of the ring die holes,thus the density of the feed particles produced could not meet the requirements.Therefore,abrasive wear under high stress is the main reason of failure at the entrance of the ring die holes under the action of feeding powder;and cutting and fatigue spalling lead to substantial material loss.In addition,a high damp-heat environment aggravates abrasive wear on the die hole internal surface.
基金supported by National Key R&D Program of China(2017YFB0305100,2017YFB0305104)the Science and Technology Planning Project of Guangdong Province No.2017B090903005+2 种基金the financial support from Jinan University(No.21620110)the financial support from Science and Technology Planning Project of Guangdong Province(No.2021A0505030042)the financial support from Guangdong Basic and Applied Basic Research Foundation(2019A1515110580)。
文摘Magnesium(Mg)alloys are attractive biodegradable implant materials.The degradation products on Mg alloys play a critical role in the stability of the interface between implant and surrounding tissue.In the present study,the effects of dynamic deformation on the interface layer of biomedical Mg-1Zn alloy were investigated using the constant extension rate tensile tests(CERT)coupled with electrochemical impedance spectroscopy(EIS).The deformation of the Mg-1Zn alloy had an adverse influence on the impedance of the surface degradation layer formed in simulated body fluid that only containing inorganic compounds.However,the surface degradation layer with improved corrosion resistance was obtained for the strained samples tested in protein-containing simulated body fluid.The spontaneous or enhanced adsorption of protein into the degradation product led to a flexible and stable hybrid anti-corrosive layer.A relationship between the dynamic deformation of Mg alloy and the impendence of the degradation layer was established,which demonstrates the necessity for in situ characterisation of the evolution of the surface layer under dynamic condition.
基金supported in part by the Light Metals Educational Foundation of Japan,and in part by the MEXT,Japan through Grants-in-Aid for Scientific Research on Innovative Areas(Nos.JP19H05176&JP21H00150)the Challenging Research Exploratory(Grant No.JP22K18737)+6 种基金W.J.Botta is grateful to the Brazilian agencies FAPESP(Grant No.2013/05987-8)CNPq(Grant Nos.421181-2018-4 and 307397-2019-0)the financial support and to the Laboratory of Structural Characterization(LCE-DEMa-UFSCar)for general electron microscopy facilities.R.Floriano thanks for the financial support from FAPESP(Grant No.2022/01351-0)support from the French State through the ANR-21-CE08-0034-01 project as well as the program“Investment in the future”operated by the National Research Agency(ANR)referenced under No.ANR-11-LABX-0008-01(Labex DAMAS)support from the National Natural Science Foundation of China(Grant No.52171205)support from the National Natural Science Foundation of China(Grant No.52071157).
文摘Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation and dehydrogenation of this group of materials.Severe plastic deformation(SPD)methods,such as equal-channel angular pressing(ECAP),high-pressure torsion(HPT),intensive rolling,and fast forging,have been widely used to enhance the activation,air resistance,and hydrogenation/dehydrogenation kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects.These severely deformed materials,particularly in the presence of alloying additives or second-phase nanoparticles,can show not only fast hydrogen absorption/desorption kinetics but also good cycling stability.It was shown that some materials that are apparently inert to hydrogen can absorb hydrogen after SPD processing.Moreover,the SPD methods were effectively used for hydrogen binding-energy engineering and synthesizing new magnesium alloys with low thermodynamic stability for reversible low/room-temperature hydrogen storage,such as nanoglasses,high-entropy alloys,and metastable phases including the high-pressureγ-MgH2 polymorph.This work reviews recent advances in the development of Mg-based hydrogen storage materials by SPD processing and discusses their potential in future applications.
基金Y.Yang was supported by Research Grant Council(RGC),Hong Kong Government,through General Research Fund(RGC)(Nos.CityU11213118,CityU11200719 and CityU11209317).
文摘High corrosion resistance of alloys is essential for their structural applications;however,most alloys suffer from degradation of their corrosion resistance with the increasing acidity of their surround-ings.Nonetheless,we developed a series of medium-entropy alloys(MEAs)in this work,which ex-hibit high strength,superior fracture toughness and ultra-high corrosion resistance,outperforming the variety of corrosion resistant alloys hitherto reported.Most interestingly,our MEAs exhibit an unusual anti-corrosion behavior and their corrosion resistance increases with acidity in Cl−containing solutions.Through extensive thermodynamic calculations,density functional theory(DFT)simulations and experi-ments,we reveal that the unusual anti-corrosion behavior of our MEAs can be attributed to their surface chemical complexity,which facilitates the physio-chemical-absorption of H_(2)O and O_(2)and thus the rapid formation of metastable medium entropy passive films that contain the lowest amount of defects,as compared to the passive films on conventional alloys reported in the literature.
基金the financial support from the National Natural Science Foundation of China(51804132 and 32101059)the Natural Science Foundation of Hebei Province(No.B2022202057)
文摘To realize economical and effective removal of hazardous 4-nitrophenol from the environment,we developed an easily recyclable ZnO nanowire array decorated with Cu nanoparticles.Its salix argyracea-shaped structure not only provides a platform to achieve stable and good dispersion of Cu nanoparticles,but also offers a great deal of catalytically active sites.The density functional theory calculations reveal that ZnO and Cu have a very beneficial synergistic effect on their catalytic capability.This synergy is ascribed to the electronic localization occurring at ZnO/Cu interface,which helps improve Cu nanoparticle’s ability to adsorb electro-negatively 4-nitrophenolate ions and to capture hydrogen radicals,thereby accelerating the hydrogen transfer from metal hydride complex to 4-nitrophenol.Benefiting from these characteristics,it exhibits high efficiency and reusability towards the catalytic reduction of waste 4-nitrophenol to valuable 4-aminophenol with a rate constant of 43.02×10^(-3)s^(-1)and an average conversion of 96.5%in 90 s during 10 cycles.This activity is superior to that of most reported noble-or non-noble-metal powder,bulk,coating,and array catalysts,indicating its competitive advantages in cost and efficiency,as well as enticing application prospects.
基金The authors would like to appreciate the financial support for this work from the National Natural Science Foundation of China(No.51701084)Research and Innovation Foundation for Young Scientists Project of Jinan University(No.21617338)China Postdoctoral Science Foundation(No.2019M663700).
文摘The wear interaction of cementite and pearlite in the white cast iron(WCI)was investigated using the two-body abrasive wear test under contact loads of 20,35,and 50 N.The wear behavior,wear surface morphology,sub-surface structure,and wear resistance were evaluated using X-ray diffraction,microhardness testing,and nano-indentation.The results indicated that when the Cr content was increased from 0 to 4 wt%,there was a significant increase in the microhardness(H)and elasticity modulus(E)of the cementite.This yielded a 15.91%-and 23.6%-reduction in the degree of wear resistance and surface roughness,respectively.Moreover,no spalling and breaking of cementite was observed with increasing Cr content during the wear process,indicating improved wear resistance of the bulk cementite.In addition,the hard phase(cementite)and tough matrix(pearlite)composite structure exhibited a good protective and supporting effect.Thus,it was concluded that the interaction mechanism of the wear phase contributed to the reduction of the wear weight loss of the composite during the wear process.The contribution of the interaction between the hard wear-resistant phase and the tough phase in WCI to the wear resistance decreased with increasing hardness of the pearlite matrix.
基金supported by the National Natural Science Foundation of China(Grant Nos.51701055)Science Foundation of China University of Petroleum,Beijing(Nos.2462018YJRC021)+2 种基金the Fundamental Research Funds for the Central Universities(21619401)National Science and Technology Major Project of the Miristry of Science and Technology of China(2016ZX05057001)National Environmental Corrosion Platform。
文摘High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure.HEAs are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios.Therefore,they can derive their performance from multiple principal elements ratherthan a single element.In this work,three-dimensional printing laser cladding was applied to produce an Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) HEA coating.The experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 μm in thickness.In the high-temperature laser cladding process,some Fe elements diffused from the substrate to the coating,forming a combination of face-centred cubic and body-centred cubic phase structures.The HEA coating metallurgically bonded well with the substrate.Owing to the increased dislocation density and number of grain boundaries,the HEA coating was harder and had a stronger hydrophobicity than X70 steel.The electrochemistry results showed that the HEA coating had better corrosion resistance than X70 steel.Aluminium oxides formed on the surface of the HEA coating had a certain protective effect.However,because of the laser cladding,the HEA coating generated cracks.In future work,the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks.
基金financial support from the National Natural Science Foundation for Youth of China(Grant No.51701083)the Guangdong Provincial Natural Science Foundation for Doctoral Research Project(Grant No.2017A030310519)+4 种基金the Fundamental Research Funds for the Central Universities(Grant No.21617340)the Scientific Research Funds for the Talents and the Innovation Foundation of Jinan University,Guangzhou,Chinathe open foundation of Guangxi Key Laboratory of Processing for Nonferrous Metals and Featured Materials,Guangxi University(Grant No.2019GXYSOF09)the Open Fund of National Joint Engineering Research Center for abrasion control and molding of metal materials(Grant No.HKDNM201903)financial support from the National Key Research and Development Project(Grant No.2020YFC1107202)。
文摘By a combination of the nanoindentation and electron probe microanalysis(EPMA)techniques,the traditional diffusion couple technique is extended to map the mechanical property of β-type Ti alloys over a wide composition range,which can be utilized to develop very versatile novel bio-Ti alloys for hard tissue re placements in arti ficial bones,joints,and dental implants.To create complete single-phase composition ranges of Ti-based bcc solid solution,12 types of bcc Ti-Nb-Zr-Mo/Ti-Nb-Zr-Ta quaternary diffusion couples were fabricated and annealed at 1273 K for 25 h.In this way,the composition-mechanical property relationships in the vast composition space of Ti-based alloys were established using EPMA and nanoindentation probes.Notably,the measured composition-dependent Young’s moduli,hardness,and elastic recovery as well as the derived ratio of hardness to Young’s modulus,and the ratio of the cube of hardness to the square of Young’s modulus,in the developed compositional mechanical property database,were visualized in a five-dimensional scatter plot.This enables an effective tool to screen the Ti-Nb-Zr-based alloys fororthopedic and dental applications according to different clinical requirements,and to rationalize the fundamental mechanical relationships in the rapid development of β-Ti alloys.
基金The authors gratefully acknowledge financial support from Guangdong Basic and Applied Basic Research Foundation,China(No.2019A15150101011282)Open Funds of National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials(2019008)the Fundamental Research Funds for the Central Universities(21619336).
文摘Here,superhydrophobic cuprous oxide(Cu2O)with hierarchical micro/nanosized structures was synthesized via sprayassisted layer by layer assembling.The asprepared superhydrophobic meshes with high contact angle(159.6°)and low sliding angle(1°)are covered with Cu_(2)O "coral reef"like micro/nanosized structures.Interestingly,the superhydrophobic mesh surfaces became superhydrophilic again due to the oxidization of Cu_(2)O to CuO by annealing at a higher temperature(300℃).And the superhydrophobic properties would be recovered by heating at 120℃.Furthermore,the superwetting meshes were applied to design a miniature device to separate light or heavy oil from the wateroil mixtures with excellent separation efficiency.These superwetting surfaces by simultaneously sprayassisted layer by layer assembling technique show the potential application in universal oilwater separation.
基金This work is financially supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51905213)the Natural Science Foundation of Guangdong(906055014066)the Fundamental Research Funds for the Central Universities(No.21619337).
文摘High-temperature tribology,which is often involved during hot metal forming,is controlled via oxidation on a rubbing surface.However,for high chromium stainless steel(ST),where oxidation is strongly inhibited,the effect of counterface materials on tribological behavior is yet to be elucidated.In this study,the effects of counterfaces on the tribological behavior of 253MA ST and mild steel(MS)are investigated via a ball-on-disc test at 900°C using a 20 N load.The results reveal that high-speed steel(HSS)experiences severe abrasive wear with MS and causes severe sticking problems with ST.Si3N4 and SiC present substantially stronger abrasive wear resistance than HSS with MS,and the friction coefficients are dependent on the type of ceramic.Both ceramics can facilitate the establishment of a thick tribo-oxide layer(>3μm)on ST to prevent sticking;however,this is accompanied by severe pull-out and fracture wear.The effects of the counterface on the mechanical properties of the tribo-oxide layer,near-surface transformation,and the responses of the tribo-oxide layer to friction and wear are discussed.This study contributes to the understanding of interfacial tribological behaviors when different types of tools are used on MS and ST.
基金support from the National Natural Science Foundation of China (51905212)Guangdong Key Laboratory of Modern Surface Engineering Technology (2020B1212060049)+2 种基金Science and Technology Project of Guangdong Academy (2021GDASYL-20210103062)Young Scientific and Technological Talents Promotion Project of Guangzhou Science and Technology Association (X20210201061)Foshan Taoyuan Institute of Advanced Manufacturing (TYKF202203003).
文摘The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.
基金funding and support by the National Natural Science Foundation of China(52004101,92166112)the Natural Science Foundation of Guangdong Province(No.2022A1515012276)+4 种基金the Educational Commission of Guangdong Province(No.2022ZDZX3002)Synchrotron X-ray beam time by the Swiss Light Source,Paul Scherrer Institute,Switzerland(proposal number 20141167,20150177 and 20160284)Diamond Light Source,UK(MT7440)Access to the University of Hull supercomputer,Viper and the support by its technical teamthe proofreading by Dr.Florian Vogel of Jinan University.
文摘Dendrites are the most common microstructural features in the cast metals,significantly affecting the structure integrity and mechanical properties of the castings.In this study,the in situ synchrotron X-ray radiographic and tomographic imaging techniques were combined to evaluate the critical fracture stress of the growing dendrite tip during the solidification of an Al-15 wt%Cu alloy under an external electromagnetic force.Two dendritic 3D models have been proposed to simulate the dendrite 3D morphologic characteristics and thus revealed that the critical fracture stresses of the Al dendrites at temperatures close to its melting point were in the range of 0.5 kPa–0.05 MPa.The present results demonstrate the feasibility of measuring the high-temperature mechanical properties of the metallic dendrites.