There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantag...There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy（HE） bulk-metallic-glass（HE-BMG） and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance（GMI） effect of MC amorphous fibers is discussed.展开更多
The FeZrB amorphous alloys for simulating the intergranular amorphous phase in the nanocrystalline Fe 89 Zr 7B 4 soft magnetic materials were obtained by mechanical alloying of a mixture of elemental Fe, Zr and ...The FeZrB amorphous alloys for simulating the intergranular amorphous phase in the nanocrystalline Fe 89 Zr 7B 4 soft magnetic materials were obtained by mechanical alloying of a mixture of elemental Fe, Zr and B powders for 25 h. It is shown that the Curie temperature of the simulated intergranular phase alloy is much lower than that of the intergranular phase with the same chemical composition in the nanocrystalline Fe 89 Zr 7B 4 alloy. The possible mechanism is mainly due to the strong ferromagnetic exchange force among the nanocrystalline α Fe grains.展开更多
In this paper, alloy powders mixed with a molar ratio of Fe ： P ： C of 80 ： 13 ： 7 were sprayed on Q235 steel by plasma spray method to prepare coating with amorphous phases. The phase composition of the mixed all...In this paper, alloy powders mixed with a molar ratio of Fe ： P ： C of 80 ： 13 ： 7 were sprayed on Q235 steel by plasma spray method to prepare coating with amorphous phases. The phase composition of the mixed alloy powders and prepared coating were characterized by X-ray diffraction （ XRD ）. The morphology and the composition cf the coating were analyzed by scanning eleetron microscopy （SEM） nnd energy dispersive apectroscopy （ EDS ）. In addition, the thermal stability ef the coating with amorphous phases was characterized by differential thermal analyzer （ DTA ）. Tile results showed that, usirtg mixed alloy powders with a molar ratio of Fe： P： C of 80：13：7, the coating containing certain amount of amorphous alloys was suceessathlly prepared through atmospheric plasma spray technique. In the coating, the main phases were determined to be Fe, FeP aad Fe2P. The crystallization of the coating started from about 461°. Tile coating was mechanically adhered to the substrate.展开更多
A new nanostructured ZrB_(2)-ZrC composite coating with ZrB_(2)-ZrC nanoscale eutectic and ZrB2+Amorphous microstructure was synthesized in situ by plasma spraying Zr-B4 C-Al composite powder.The thermal analysis,quen...A new nanostructured ZrB_(2)-ZrC composite coating with ZrB_(2)-ZrC nanoscale eutectic and ZrB2+Amorphous microstructure was synthesized in situ by plasma spraying Zr-B4 C-Al composite powder.The thermal analysis,quenching experiments and microstructure characterization were investigated and the formation mechanism of the bimodal in-situ microstructure was revealed.Al contributed to the liquid phase separation of molten droplets,which is the key to forming ZrB2+Amorphous microstructure.The formation of coating followed reaction-melting-liquid separation-deposition and solidification mechanism.The nanostructured ZrB_(2)-ZrC composite coating with Al-O intergranular amorphous phase has excellent mechanical properties.The uniform nano-grains improved the hardness and the toughness of the ZrB_(2)-ZrC eutectic.The ZrB_(2)+Al-O amorphous microstructure obtained high toughness and the toughening mechanism was the crack deflection and crack branching caused by intergranular Al-O amorphous phase.展开更多
The creep behaviors of the amorphous phase in a CuZr-based bulk metallic glass composite(BMGC)are studied by nanoindentation.Samples fabricated via higher cooling rates are found to exhibit more prominent creep,but a ...The creep behaviors of the amorphous phase in a CuZr-based bulk metallic glass composite(BMGC)are studied by nanoindentation.Samples fabricated via higher cooling rates are found to exhibit more prominent creep,but a smaller shear viscosity.The volume of the shear transformation zones(STZs)in the amorphous phase calculated based on a cooperative shear model increases with the cooling rate.The evolution of excess free volume created during creep deformation is clarified.A looser atomic arrangement leads to a larger STZ volume,thus facilitating creep deformation.This study gives a better understanding of the deformation behaviors of the amorphous phase in BMGCs.展开更多
To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and SiC.Th...To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and SiC.The wear and corrosion behaviours of the coatings were investigated.The wear resistance of the coatings was evaluated under dry sliding wear condition at room temperature.The corrosion resistance of the coatings was tested in 3.5%(mass fraction) NaCl solution.The coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic compounds.The main wear mechanisms of the coatings and the AZ91D sample are different.The former is abrasive wear and the latter is adhesive wear.The coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.展开更多
The rational design of strong affinity adsorbents for heavy metal ions removal remains a critical challenge for water treatment.In this study,amorphous molybdenum sulfide composites(EDTA-MoSx(x=2,3))were fabricated vi...The rational design of strong affinity adsorbents for heavy metal ions removal remains a critical challenge for water treatment.In this study,amorphous molybdenum sulfide composites(EDTA-MoSx(x=2,3))were fabricated via a facile hydrothermal method mediated by EDTA,which was applied to heavy metal ions(Cu^(2+),Cd^(2+),Pb^(2+),Zn^(2+)and Ni^(2+))removal from aqueous solutions.A case study for Cu^(2+)ions showed that the adsorption capacity of EDTA-MoSx(x=2,3)was superior to crystalline phase MoS2 at pH 6.0 with an initial concentration of 200 mg/L.Adsorption mechanisms of different sulfide groups and—COOH of EDTA-MoSx(x=2,3)were verified systematically via a series of experiments,characterizations,and density functional theory(DFT)calculations.Both bridging S_(2)^(2-)and—COOH covalently bonded with Cu^(2+)ions were ascribed to the critical factors for this enhanced removal efficiency on the surface of EDTA-MoSx(x=2,3).This work offers a new method to enhance the adsorption performance of molybdenum sulfide-based materials by controlling crystallinity mediated with an organic complex small molecule.展开更多
In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu c...In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu content on phase formation,microstructure,and mechanical properties is investigated.The average volume fraction and width of theβphase decreases with increasing Cu content,while a more amorphous phase and the(Ti,Zr)_(2)Cu phase forms.In the center zone of the molten pool,theβphase grows in the direction of the temperature gradient,and the amorphous phase distributes among theβphases.This occurs using:sphere morphology(for x=5),a more continuous elongated sphere and network morphology(for x=10),and network morphology(for x=15),respectively.In the edge zone of the molten pool,due to the smaller cooling rate and the existence of a partially molten zone,theβphase becomes coarser,and an amorphous phase forms for more continuous networks.Furthermore,the hardness improves significantly with increasing Cu content.No crack is found for x=5.Although the average volume fraction of theβphase for x=5 is about 90%,the compression yield strength is 1386±64 MPa,reaching to an average level of conventionally fabricated counterparts,due to finer microstructure,and twinning and martensitic transformation of theβphase.展开更多
High undercooling up to 392 K was achieved in eutectic Ni70.2Si29.8 alloy melt by using glass fluxing combined with cyclic superheating. A small quantity of amorphous phase was obtained in bulk eutectic Ni70.2Si29.8 a...High undercooling up to 392 K was achieved in eutectic Ni70.2Si29.8 alloy melt by using glass fluxing combined with cyclic superheating. A small quantity of amorphous phase was obtained in bulk eutectic Ni70.2Si29.8 alloy when undercooling exceeds 240 K under slow cooling conditions （about 1 K/s）. The amorphous phase was confirmed by high-resolution transmission electron microscopy and differential scanning calorimetry.展开更多
The high velocity oxy-fuel(HVOF) based thermal spray process has developed as a potential advantageous approach for fabricating various kinds of functional coatings.In this article,the coatings of Mo-based alloy were ...The high velocity oxy-fuel(HVOF) based thermal spray process has developed as a potential advantageous approach for fabricating various kinds of functional coatings.In this article,the coatings of Mo-based alloy were synthesized using the HVOF process.The microstructure and the mechanical properties of the HVOF-processed coatings were investigated using SEM,TEM,XRD,and hardness and wear tests.Annealing treatment was applied to the as-sprayed coatings to develop the microstructure and its effect on the microstructure and mechanical properties of the coatings was examined.It is found that the HVOF-processed Mo-based alloy coatings are comprised of an amorphous splat matrix embedded with nano-sized crystalline particles.Annealing at temperatures over 950 ℃ results into crystallization of the amorphous matrix.The mechanical properties of the as-sprayed coatings are enhanced with annealing temperature up to 750 ℃ and from 950 to 1050 ℃,keeps constant between 750 and 950 ℃,and reduce over 1050 ℃.The change of the mechanical property with the microstructure was illustrated in the study.展开更多
In this study,Al-30W(wt.%)alloy powder was prepared by Aluminothermic reduction and hightemperature gas atomization.We then studied the phase composition,surface morphology,spatial phase structure,and thermal oxidatio...In this study,Al-30W(wt.%)alloy powder was prepared by Aluminothermic reduction and hightemperature gas atomization.We then studied the phase composition,surface morphology,spatial phase structure,and thermal oxidation process using XRD,SEM/EDS,TEM,DSC,and DTA/TG analysis.The results showed that the Al-30W alloy powder exhibited high sphericity,and the interior presented a special spatial phase structure in which the Al/W amorphous alloy phase and the metastable Al/W intermetallic compound phase were distributed in the pure Al matrix.When the Al-30W alloy powder was stabilized in a vacuum tube furnace,the spatial phase structure of the alloy powder changed,and a small amount of pure Al was embedded in the Al_(12)W matrix.The resulting Al-30W alloy powder products,treated in air at different temperatures,were collected in situ and characterized.The results presented that with an increase in temperature,the types and morphologies of the Al/W intermetallic compounds in the Al-30W alloy powder changed.Furthermore,the Al-30W alloy powder began to undergo intense oxidation reactions at about 900℃,accompanied by a concentrated energy release and rapid weight gain.The volatilization of WO_(3)produced in the oxidation process promoted the complete oxidation of the Al-30W alloy powder,and the Al-30W alloy powder was completely oxidized at 1300℃.At this stage,all W atoms were transformed into gaseous WO_(3),and only a large number of small Al_(2)O_(3)fragments remained in the oxidation product.Thus,the Al-30W alloy powder exhibited excellent thermal reactivity and oxidation integrity,and may offer excellent application prospects in the field of energetic materials.展开更多
This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying（MA） process. The Cr–35Mo（in at%） powder mixture was milled at 24...This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying（MA） process. The Cr–35Mo（in at%） powder mixture was milled at 243 and258 K, respectively, for different time. For comparative study, Cr–15Mo and Cr–62Mo powder mixtures were milled at 243 K for 18 h. Solid solution Cr（Mo） with body-centered cubic（bcc） crystal structure and amorphous Cr（Mo） alloy was obtained during MA process caused by high-energy ball milling. Based on the Miedema＇s model, the free-energy change for forming either a solid solution or an amorphous in Cr–Mo alloy system is positive but small at a temperature range between 200 and 300 K. The thermodynamical barrier for forming alloy in Cr–Mo system can be overcome when MA occurs at 243 K, and the supersaturated solid solution crystal nuclei with bcc structure form continually, and three supersaturated solid solutions of Cr–62Mo, Cr–35Mo and Cr–15Mo formed. Milling the Cr–35Mo powder mixture at 258 K, the solid solution Cr（Mo） forms firstly, and then the solid solution Cr（Mo） transforms into the amorphous Cr（Mo）alloy with a few of nanocrystallines when milling is prolonged. At higher milling temperature, it is favorable for the formation of the amorphous phase, as indicated by the thermodynamical calculation for immiscible Cr–Mo alloy system.展开更多
Efficient and cost‐effective catalysts for oxygen reduction reaction(ORR)are crucial for the commercialization of metal‐air batteries.In this study,we utilized theoretical calculations to guide the material synthesi...Efficient and cost‐effective catalysts for oxygen reduction reaction(ORR)are crucial for the commercialization of metal‐air batteries.In this study,we utilized theoretical calculations to guide the material synthesis strategy for preparing catalysts.Using density functional theory(DFT)calculations,we systematically explored the ORR performance of metal metaphosphates(A‐M(PO_(3))_(2),B‐M(PO_(3))_(2),M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,and Zn)with both amorphous and crystalline structures.Amorphous A‐Mn(PO_(3))_(2)showed optimal adsorption energy and the lowest ORR overpotential of 0.32 eV.Phytic acid was employed as a phosphorus source,and the chelating structure of phytic acid molecules and metal ions was broken through the“metal ion pre‐adsorption and spatial confinement strategy”of carbon materials with electron‐rich centers.Following high‐temperature calcination,we successfully prepared a series of amorphous metal metaphosphate composite catalysts for the first time.In 0.1M KOH electrolyte,both amorphous Mn(PO_(3))_(2)‐C/C_(3)N_(4)/CQDs(carbon quantum dots)and Mn(PO_(3))_(2)‐C/C3N4/CNTs(carbon nanotubes)exhibited excellent ORR catalytic activity,with half‐wave potentials of 0.85 V and 0.80 V,respectively.A linear correlation between theoretical overpotentials and experimental half‐wave potentials was discovered through comparison.This work could open a new avenue to the discovery of highly efficient non‐precious metal‐based catalysts with amorphous structures.展开更多
Immiscible Cu-W alloy thin films were prepared using dual-target magnetron sputtering deposition process. The structure evolution of Cu-W thin films during preparation was investigated by X-ray diffraction, transmissi...Immiscible Cu-W alloy thin films were prepared using dual-target magnetron sputtering deposition process. The structure evolution of Cu-W thin films during preparation was investigated by X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy. In the initial stage of dual-target magnetron sputtering deposition process, an amorphous phase formed; then it crystallized and the analogy spinodal structure formed due to the bombardment of the sputtered particles during sputtering deposition process, the surface structure of the film without the bombardment of the sputtered particles was the amorphous one, the distribution of the crystalline and amorphous phase showed layer structure. The solid solubility with the analogy spinodal structure was calculated using the Vegard law. For Cu-13.7%W （mole fraction） film, its structure was composed of Cu-ll%W solution, Cu-37%W solution and pure Cu; for Cu 14.3%W film, it was composed of Cu-15%W solution, Cu-38%W solution, and pure Cu; for Cu-18.1%W film, it was composed of Cu-19%W solution, Cu-36% W solution and pure Cu.展开更多
The phase evolution,microstructure and magnetic properties of Nd9-xYxFe72Ti2Zr2B15(x=0,0.5,1,2) nanocomposite ribbons were investigated.It was found that substitution of Y enhanced glass forming ability of the over-qu...The phase evolution,microstructure and magnetic properties of Nd9-xYxFe72Ti2Zr2B15(x=0,0.5,1,2) nanocomposite ribbons were investigated.It was found that substitution of Y enhanced glass forming ability of the over-quenched ribbons and stabilized the amorphous phase during post annealing treatment.Appropriate content of Y substitution effectively refined the microstructure and enhanced the remanence of the annealed samples.The residual amorphous intergranular phase in the annealed sample improved the square...展开更多
The rare earth ion Ce 4+ doped TiO 2 was prepared by sol-gel method. The average particle sizes are about 10 nm for sol phase and 55 nm for polycrystalline phase. The photocatalytic activities to degrade Reactive ...The rare earth ion Ce 4+ doped TiO 2 was prepared by sol-gel method. The average particle sizes are about 10 nm for sol phase and 55 nm for polycrystalline phase. The photocatalytic activities to degrade Reactive Brilliant Red Dye X-3B were investigated. The result reveals that the spectrum response of Ce 4+-TiO 2 has extended to visible region from the UV region(λ<387 nm) of pure TiO 2. Amorphous phase Ce 4+-TiO 2 sol with an electron scavenger (1.0% atom fraction Ce 4+ ion doping amount) shows the capability of the photocatalytic degradation of the dye X-3B as well as the nanocrystallite Ce 4+-TiO 2 with an interband trap site. Despite of the difference in the morphology of Ce 4+-TiO 2 photocatalyst, there is no apparent difference in respect of the decoloring effects. Whereas, polycrystalline phase Ce 4+-TiO 2 exhibits strong photomineralization power in comparison with the amorphous phase. The photocatalytic oxidation mechanisms of the dye molecule mainly involved in the self-photo-sensitization photolysis process by the first excited singlet oxygen ( 1O 2) and photocatalysis process by hydroxyl radicals(·OH) under visible light irradiation.展开更多
The phase evolution and magnetic properties of Nd9？xYxFe72Ti2Zr2B15 （x = 0,0.5,1,and 2） melt-spun nanocomposite ribbons were studied.It is found that Y addition not only enhances the formability of amorphous phase ...The phase evolution and magnetic properties of Nd9？xYxFe72Ti2Zr2B15 （x = 0,0.5,1,and 2） melt-spun nanocomposite ribbons were studied.It is found that Y addition not only enhances the formability of amorphous phase in the alloy,but also stabilizes the amorphous phase during the annealing treatment.The appropriate content of Y addition effectively enhances the remanence （Jr） of the annealed sample.The residual amorphous intergranular phase in the annealed sample optimizes the squareness of the loop,resulting in an larger maximum energy product （BH）max.The best magnetic properties,Jr = 0.78 T,Hci （coercivity） = 923.4 kA/m,and （BH）max = 98.5 kJ/m3,were obtained from the Nd8YFe72Ti2Zr2B15 ribbon spun at Vs = 4 m/s and annealed at 700°C for 10 min,which is composed of Nd2Fe14B,α-Fe,and amorphous phase.展开更多
The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies h...The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies have evaluated their influence in road dust composition.Air quality in urban areas is significantly affected by nonexhaust emissions(e.g.road dust,brake wear,tire wear),however,natural sources such as volcanoes also impact the chemical composition of the particles.In this study,elements from volcanic emissions such as Si>Al>Fe>Ca>K>Mg,and Si-Al with K were identified as complex hydrates.Similarly,As,Hg,Cd,Pb,As,H,Cd,Pb,V,and salammoniac were observed in nanoparticles and ultrafine material.Mineral composition was detected in the order of quartz>mullite>calcite>kaolinite>illite>goethite>magnetite>zircon>monazite,in addition to salammoniac,a tracer of volcanic sources.The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health.The road dust load(RD_(10))ranged between 0.8 and 26.8 mg m^(−2)in the city.展开更多
Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly...Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly turns down after some impact cycles when the impact load is greater than the critical load. The critical impact load is smaller than 8.2 J in this research because the nano-sized austenitic grains embedded in amorphous delay the crack propagation in subsurface. From high resolution transmission electron microscope (HRTEM) examination of subsurface microstructure, it is found that a large amount of nano-sized grains embedded in bulk amorphous matrix are fully developed and no martensitic transformation occurs during the impact wear process. The analytical results of worn surface morphology and debris indicate that the initiation of crack, propagation and spalling are restricted in the amorphous phase, resulting in the size distribution of debris in nano-sizes, which is the reason why the wear rate of Hadfield steel is greatly decreased at high impact load.展开更多
Nanostructured Mg-3Ni-2MnO_(2) was synthesized by ball milling elemental powders of Mg,Ni and MnO_(2) in hydrogen atmosphere.The microstructures of the powder prepared at different milling time were analyzed by X-ray ...Nanostructured Mg-3Ni-2MnO_(2) was synthesized by ball milling elemental powders of Mg,Ni and MnO_(2) in hydrogen atmosphere.The microstructures of the powder prepared at different milling time were analyzed by X-ray diffractometry(XRD), scanning electron microscopy(SEM)and high resolution electron microscopy(HREM).The milling time is the most key parameter impacting on the grain size and the microstructure of material.With prolonging the milling time,particle size becomes smaller and smaller.But after the ball milling time reaches about 20 h,reduction of grain size becomes slowly.When the milling time is more than 50 h,nanocrystalline fully forms.When the milling time is more than 80 h,there are more amorphous phases in materials.The average particle diameter of material is about 1μm and the grain size is 10-30 nm.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51471025)
文摘There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy（HE） bulk-metallic-glass（HE-BMG） and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance（GMI） effect of MC amorphous fibers is discussed.
文摘The FeZrB amorphous alloys for simulating the intergranular amorphous phase in the nanocrystalline Fe 89 Zr 7B 4 soft magnetic materials were obtained by mechanical alloying of a mixture of elemental Fe, Zr and B powders for 25 h. It is shown that the Curie temperature of the simulated intergranular phase alloy is much lower than that of the intergranular phase with the same chemical composition in the nanocrystalline Fe 89 Zr 7B 4 alloy. The possible mechanism is mainly due to the strong ferromagnetic exchange force among the nanocrystalline α Fe grains.
文摘In this paper, alloy powders mixed with a molar ratio of Fe ： P ： C of 80 ： 13 ： 7 were sprayed on Q235 steel by plasma spray method to prepare coating with amorphous phases. The phase composition of the mixed alloy powders and prepared coating were characterized by X-ray diffraction （ XRD ）. The morphology and the composition cf the coating were analyzed by scanning eleetron microscopy （SEM） nnd energy dispersive apectroscopy （ EDS ）. In addition, the thermal stability ef the coating with amorphous phases was characterized by differential thermal analyzer （ DTA ）. Tile results showed that, usirtg mixed alloy powders with a molar ratio of Fe： P： C of 80：13：7, the coating containing certain amount of amorphous alloys was suceessathlly prepared through atmospheric plasma spray technique. In the coating, the main phases were determined to be Fe, FeP aad Fe2P. The crystallization of the coating started from about 461°. Tile coating was mechanically adhered to the substrate.
基金supports of the National Natural Science Foundation of China(Nos.52371063 and 52072110)the Natural Science Foundation of Hebei Province(No.E2018202034)the Central Funds Guiding the Local Science and Technology Development of Hebei Province(No.236Z7610G).
文摘A new nanostructured ZrB_(2)-ZrC composite coating with ZrB_(2)-ZrC nanoscale eutectic and ZrB2+Amorphous microstructure was synthesized in situ by plasma spraying Zr-B4 C-Al composite powder.The thermal analysis,quenching experiments and microstructure characterization were investigated and the formation mechanism of the bimodal in-situ microstructure was revealed.Al contributed to the liquid phase separation of molten droplets,which is the key to forming ZrB2+Amorphous microstructure.The formation of coating followed reaction-melting-liquid separation-deposition and solidification mechanism.The nanostructured ZrB_(2)-ZrC composite coating with Al-O intergranular amorphous phase has excellent mechanical properties.The uniform nano-grains improved the hardness and the toughness of the ZrB_(2)-ZrC eutectic.The ZrB_(2)+Al-O amorphous microstructure obtained high toughness and the toughening mechanism was the crack deflection and crack branching caused by intergranular Al-O amorphous phase.
基金supported by the National Natural Science Foundation of China(Grant Nos.51827801,51871076,51671070 and 51671071)the Kingboard Professorship Endowment of the University of Hong Kong。
文摘The creep behaviors of the amorphous phase in a CuZr-based bulk metallic glass composite(BMGC)are studied by nanoindentation.Samples fabricated via higher cooling rates are found to exhibit more prominent creep,but a smaller shear viscosity.The volume of the shear transformation zones(STZs)in the amorphous phase calculated based on a cooperative shear model increases with the cooling rate.The evolution of excess free volume created during creep deformation is clarified.A looser atomic arrangement leads to a larger STZ volume,thus facilitating creep deformation.This study gives a better understanding of the deformation behaviors of the amorphous phase in BMGCs.
基金Project(AWPT08-10)supported by the Open Fund of the State Key Laboratory of Advanced Welding Production Technology in Harbin Institute of Technology,ChinaProject(mmlab0706)supported by the Open Fund of the State Key Laboratory of Materials Modification by Laser,Ion and Electron Beams in Dalian University of University,ChinaProject(0710908-05-K)supported by the Research Funds of the Guangxi Key Laboratory of Information Materials in Guilin University of Electronic Technology,China
文摘To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and SiC.The wear and corrosion behaviours of the coatings were investigated.The wear resistance of the coatings was evaluated under dry sliding wear condition at room temperature.The corrosion resistance of the coatings was tested in 3.5%(mass fraction) NaCl solution.The coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic compounds.The main wear mechanisms of the coatings and the AZ91D sample are different.The former is abrasive wear and the latter is adhesive wear.The coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.
基金supported by the Natural Science Foundation of Tianjin(No.18JCYBJC17700)the National Natural Science Foundation of China(Nos.21406164,21466035 and 22066022)the National Key Basic Research and Development Program of China(973 Program,No.2014CB239300)。
文摘The rational design of strong affinity adsorbents for heavy metal ions removal remains a critical challenge for water treatment.In this study,amorphous molybdenum sulfide composites(EDTA-MoSx(x=2,3))were fabricated via a facile hydrothermal method mediated by EDTA,which was applied to heavy metal ions(Cu^(2+),Cd^(2+),Pb^(2+),Zn^(2+)and Ni^(2+))removal from aqueous solutions.A case study for Cu^(2+)ions showed that the adsorption capacity of EDTA-MoSx(x=2,3)was superior to crystalline phase MoS2 at pH 6.0 with an initial concentration of 200 mg/L.Adsorption mechanisms of different sulfide groups and—COOH of EDTA-MoSx(x=2,3)were verified systematically via a series of experiments,characterizations,and density functional theory(DFT)calculations.Both bridging S_(2)^(2-)and—COOH covalently bonded with Cu^(2+)ions were ascribed to the critical factors for this enhanced removal efficiency on the surface of EDTA-MoSx(x=2,3).This work offers a new method to enhance the adsorption performance of molybdenum sulfide-based materials by controlling crystallinity mediated with an organic complex small molecule.
基金supported by the National Key Research and Development Plan of China(No.2018YFB0704101)the Fundamental Research Funds for the Central Universities(No.3102019ZX013)the Planning Programme of Shan Xi Province’s Co-Ordination and Innovation Project of Science and Technology(No.2016KTZDCY02-02)。
文摘In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu content on phase formation,microstructure,and mechanical properties is investigated.The average volume fraction and width of theβphase decreases with increasing Cu content,while a more amorphous phase and the(Ti,Zr)_(2)Cu phase forms.In the center zone of the molten pool,theβphase grows in the direction of the temperature gradient,and the amorphous phase distributes among theβphases.This occurs using:sphere morphology(for x=5),a more continuous elongated sphere and network morphology(for x=10),and network morphology(for x=15),respectively.In the edge zone of the molten pool,due to the smaller cooling rate and the existence of a partially molten zone,theβphase becomes coarser,and an amorphous phase forms for more continuous networks.Furthermore,the hardness improves significantly with increasing Cu content.No crack is found for x=5.Although the average volume fraction of theβphase for x=5 is about 90%,the compression yield strength is 1386±64 MPa,reaching to an average level of conventionally fabricated counterparts,due to finer microstructure,and twinning and martensitic transformation of theβphase.
基金supported financially by the National Natural Science Foundation of China (No. 50395103)the Doctorate Foundation of North western Poly technical University (CX200506)
文摘High undercooling up to 392 K was achieved in eutectic Ni70.2Si29.8 alloy melt by using glass fluxing combined with cyclic superheating. A small quantity of amorphous phase was obtained in bulk eutectic Ni70.2Si29.8 alloy when undercooling exceeds 240 K under slow cooling conditions （about 1 K/s）. The amorphous phase was confirmed by high-resolution transmission electron microscopy and differential scanning calorimetry.
基金supported by the National 863 projects by the Department of Science and Technology of China (No. 2002AA331080)the Program of Beijing Significant Science and Technology Project (No.020420050021)
文摘The high velocity oxy-fuel(HVOF) based thermal spray process has developed as a potential advantageous approach for fabricating various kinds of functional coatings.In this article,the coatings of Mo-based alloy were synthesized using the HVOF process.The microstructure and the mechanical properties of the HVOF-processed coatings were investigated using SEM,TEM,XRD,and hardness and wear tests.Annealing treatment was applied to the as-sprayed coatings to develop the microstructure and its effect on the microstructure and mechanical properties of the coatings was examined.It is found that the HVOF-processed Mo-based alloy coatings are comprised of an amorphous splat matrix embedded with nano-sized crystalline particles.Annealing at temperatures over 950 ℃ results into crystallization of the amorphous matrix.The mechanical properties of the as-sprayed coatings are enhanced with annealing temperature up to 750 ℃ and from 950 to 1050 ℃,keeps constant between 750 and 950 ℃,and reduce over 1050 ℃.The change of the mechanical property with the microstructure was illustrated in the study.
基金supported by the National Natural Science Foundation of China(No.51871106).We express our grat-itude for analyzing and testing of Huazhong University of Science and Technology Analytical&Testing Center.
文摘In this study,Al-30W(wt.%)alloy powder was prepared by Aluminothermic reduction and hightemperature gas atomization.We then studied the phase composition,surface morphology,spatial phase structure,and thermal oxidation process using XRD,SEM/EDS,TEM,DSC,and DTA/TG analysis.The results showed that the Al-30W alloy powder exhibited high sphericity,and the interior presented a special spatial phase structure in which the Al/W amorphous alloy phase and the metastable Al/W intermetallic compound phase were distributed in the pure Al matrix.When the Al-30W alloy powder was stabilized in a vacuum tube furnace,the spatial phase structure of the alloy powder changed,and a small amount of pure Al was embedded in the Al_(12)W matrix.The resulting Al-30W alloy powder products,treated in air at different temperatures,were collected in situ and characterized.The results presented that with an increase in temperature,the types and morphologies of the Al/W intermetallic compounds in the Al-30W alloy powder changed.Furthermore,the Al-30W alloy powder began to undergo intense oxidation reactions at about 900℃,accompanied by a concentrated energy release and rapid weight gain.The volatilization of WO_(3)produced in the oxidation process promoted the complete oxidation of the Al-30W alloy powder,and the Al-30W alloy powder was completely oxidized at 1300℃.At this stage,all W atoms were transformed into gaseous WO_(3),and only a large number of small Al_(2)O_(3)fragments remained in the oxidation product.Thus,the Al-30W alloy powder exhibited excellent thermal reactivity and oxidation integrity,and may offer excellent application prospects in the field of energetic materials.
基金National Natural Science Foundation of China (Nos. 51271143 and 51302247)
文摘This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying（MA） process. The Cr–35Mo（in at%） powder mixture was milled at 243 and258 K, respectively, for different time. For comparative study, Cr–15Mo and Cr–62Mo powder mixtures were milled at 243 K for 18 h. Solid solution Cr（Mo） with body-centered cubic（bcc） crystal structure and amorphous Cr（Mo） alloy was obtained during MA process caused by high-energy ball milling. Based on the Miedema＇s model, the free-energy change for forming either a solid solution or an amorphous in Cr–Mo alloy system is positive but small at a temperature range between 200 and 300 K. The thermodynamical barrier for forming alloy in Cr–Mo system can be overcome when MA occurs at 243 K, and the supersaturated solid solution crystal nuclei with bcc structure form continually, and three supersaturated solid solutions of Cr–62Mo, Cr–35Mo and Cr–15Mo formed. Milling the Cr–35Mo powder mixture at 258 K, the solid solution Cr（Mo） forms firstly, and then the solid solution Cr（Mo） transforms into the amorphous Cr（Mo）alloy with a few of nanocrystallines when milling is prolonged. At higher milling temperature, it is favorable for the formation of the amorphous phase, as indicated by the thermodynamical calculation for immiscible Cr–Mo alloy system.
基金supported by National Natural Science Foundation of China(22273069)the Scientific Research Project of Education Department of Hubei Province(B2023158)+1 种基金the Open Fund of the Hubei Provincial Key Laboratory of Green Materials for Light Industry(202307A07)the Natural Science Foundation of Xiaogan City(XGKJ2023010058).
文摘Efficient and cost‐effective catalysts for oxygen reduction reaction(ORR)are crucial for the commercialization of metal‐air batteries.In this study,we utilized theoretical calculations to guide the material synthesis strategy for preparing catalysts.Using density functional theory(DFT)calculations,we systematically explored the ORR performance of metal metaphosphates(A‐M(PO_(3))_(2),B‐M(PO_(3))_(2),M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,and Zn)with both amorphous and crystalline structures.Amorphous A‐Mn(PO_(3))_(2)showed optimal adsorption energy and the lowest ORR overpotential of 0.32 eV.Phytic acid was employed as a phosphorus source,and the chelating structure of phytic acid molecules and metal ions was broken through the“metal ion pre‐adsorption and spatial confinement strategy”of carbon materials with electron‐rich centers.Following high‐temperature calcination,we successfully prepared a series of amorphous metal metaphosphate composite catalysts for the first time.In 0.1M KOH electrolyte,both amorphous Mn(PO_(3))_(2)‐C/C_(3)N_(4)/CQDs(carbon quantum dots)and Mn(PO_(3))_(2)‐C/C3N4/CNTs(carbon nanotubes)exhibited excellent ORR catalytic activity,with half‐wave potentials of 0.85 V and 0.80 V,respectively.A linear correlation between theoretical overpotentials and experimental half‐wave potentials was discovered through comparison.This work could open a new avenue to the discovery of highly efficient non‐precious metal‐based catalysts with amorphous structures.
文摘Immiscible Cu-W alloy thin films were prepared using dual-target magnetron sputtering deposition process. The structure evolution of Cu-W thin films during preparation was investigated by X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy. In the initial stage of dual-target magnetron sputtering deposition process, an amorphous phase formed; then it crystallized and the analogy spinodal structure formed due to the bombardment of the sputtered particles during sputtering deposition process, the surface structure of the film without the bombardment of the sputtered particles was the amorphous one, the distribution of the crystalline and amorphous phase showed layer structure. The solid solubility with the analogy spinodal structure was calculated using the Vegard law. For Cu-13.7%W （mole fraction） film, its structure was composed of Cu-ll%W solution, Cu-37%W solution and pure Cu; for Cu 14.3%W film, it was composed of Cu-15%W solution, Cu-38%W solution, and pure Cu; for Cu-18.1%W film, it was composed of Cu-19%W solution, Cu-36% W solution and pure Cu.
文摘The phase evolution,microstructure and magnetic properties of Nd9-xYxFe72Ti2Zr2B15(x=0,0.5,1,2) nanocomposite ribbons were investigated.It was found that substitution of Y enhanced glass forming ability of the over-quenched ribbons and stabilized the amorphous phase during post annealing treatment.Appropriate content of Y substitution effectively refined the microstructure and enhanced the remanence of the annealed samples.The residual amorphous intergranular phase in the annealed sample improved the square...
文摘The rare earth ion Ce 4+ doped TiO 2 was prepared by sol-gel method. The average particle sizes are about 10 nm for sol phase and 55 nm for polycrystalline phase. The photocatalytic activities to degrade Reactive Brilliant Red Dye X-3B were investigated. The result reveals that the spectrum response of Ce 4+-TiO 2 has extended to visible region from the UV region(λ<387 nm) of pure TiO 2. Amorphous phase Ce 4+-TiO 2 sol with an electron scavenger (1.0% atom fraction Ce 4+ ion doping amount) shows the capability of the photocatalytic degradation of the dye X-3B as well as the nanocrystallite Ce 4+-TiO 2 with an interband trap site. Despite of the difference in the morphology of Ce 4+-TiO 2 photocatalyst, there is no apparent difference in respect of the decoloring effects. Whereas, polycrystalline phase Ce 4+-TiO 2 exhibits strong photomineralization power in comparison with the amorphous phase. The photocatalytic oxidation mechanisms of the dye molecule mainly involved in the self-photo-sensitization photolysis process by the first excited singlet oxygen ( 1O 2) and photocatalysis process by hydroxyl radicals(·OH) under visible light irradiation.
文摘The phase evolution and magnetic properties of Nd9？xYxFe72Ti2Zr2B15 （x = 0,0.5,1,and 2） melt-spun nanocomposite ribbons were studied.It is found that Y addition not only enhances the formability of amorphous phase in the alloy,but also stabilizes the amorphous phase during the annealing treatment.The appropriate content of Y addition effectively enhances the remanence （Jr） of the annealed sample.The residual amorphous intergranular phase in the annealed sample optimizes the squareness of the loop,resulting in an larger maximum energy product （BH）max.The best magnetic properties,Jr = 0.78 T,Hci （coercivity） = 923.4 kA/m,and （BH）max = 98.5 kJ/m3,were obtained from the Nd8YFe72Ti2Zr2B15 ribbon spun at Vs = 4 m/s and annealed at 700°C for 10 min,which is composed of Nd2Fe14B,α-Fe,and amorphous phase.
文摘The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies have evaluated their influence in road dust composition.Air quality in urban areas is significantly affected by nonexhaust emissions(e.g.road dust,brake wear,tire wear),however,natural sources such as volcanoes also impact the chemical composition of the particles.In this study,elements from volcanic emissions such as Si>Al>Fe>Ca>K>Mg,and Si-Al with K were identified as complex hydrates.Similarly,As,Hg,Cd,Pb,As,H,Cd,Pb,V,and salammoniac were observed in nanoparticles and ultrafine material.Mineral composition was detected in the order of quartz>mullite>calcite>kaolinite>illite>goethite>magnetite>zircon>monazite,in addition to salammoniac,a tracer of volcanic sources.The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health.The road dust load(RD_(10))ranged between 0.8 and 26.8 mg m^(−2)in the city.
基金Project(59771048) supported by the National Natural Science Foundation of China project(2002AA302509) supportedby the High Technology Research and Development Program of China
文摘Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly turns down after some impact cycles when the impact load is greater than the critical load. The critical impact load is smaller than 8.2 J in this research because the nano-sized austenitic grains embedded in amorphous delay the crack propagation in subsurface. From high resolution transmission electron microscope (HRTEM) examination of subsurface microstructure, it is found that a large amount of nano-sized grains embedded in bulk amorphous matrix are fully developed and no martensitic transformation occurs during the impact wear process. The analytical results of worn surface morphology and debris indicate that the initiation of crack, propagation and spalling are restricted in the amorphous phase, resulting in the size distribution of debris in nano-sizes, which is the reason why the wear rate of Hadfield steel is greatly decreased at high impact load.
文摘Nanostructured Mg-3Ni-2MnO_(2) was synthesized by ball milling elemental powders of Mg,Ni and MnO_(2) in hydrogen atmosphere.The microstructures of the powder prepared at different milling time were analyzed by X-ray diffractometry(XRD), scanning electron microscopy(SEM)and high resolution electron microscopy(HREM).The milling time is the most key parameter impacting on the grain size and the microstructure of material.With prolonging the milling time,particle size becomes smaller and smaller.But after the ball milling time reaches about 20 h,reduction of grain size becomes slowly.When the milling time is more than 50 h,nanocrystalline fully forms.When the milling time is more than 80 h,there are more amorphous phases in materials.The average particle diameter of material is about 1μm and the grain size is 10-30 nm.
