Fe(83.2-x)CoxP(10)C6Cu(0.8)(x=0,4,6,8 and 10)alloys with a high amorphous-forming ability and good softmagnetic properties were successfully synthesized.Saturation magnetic flux density(Bs)is effectively enhanced from...Fe(83.2-x)CoxP(10)C6Cu(0.8)(x=0,4,6,8 and 10)alloys with a high amorphous-forming ability and good softmagnetic properties were successfully synthesized.Saturation magnetic flux density(Bs)is effectively enhanced from 1.53 T to 1.61 T for as-quenched alloy by minor Co addition,which is consistent well with the result of the linear relationship between average magnetic moment and magnetic valence.For Cocontained alloys,the value of corecivity(Hc)is mainly determined by magneto-crystalline anisotropy,while effective permeability(μe)is dominated by grain size and average saturation polarization.After proper heat treatment,the Fe(79.2)Co4P(10)C6Cu(0.8)nanocrystalline alloy exhibited excellent soft-magnetic properties including a high Bsof 1.8 T,a low Hcof 6.6 A/m and a highμeof 15,510,which is closely related to the high volume fraction of α-(Fe,Co)grains and refined uniform nanocrystalline microstructure.展开更多
Abstract： This study deals with the Fe65.5Cr4Mo4Ga4P12C5B5.5 ferromagnetic bulk amorphous alloy. XRD analysis showed an amorphous structure of the as-cast sample. The same method revealed that, after annealing at 973...Abstract： This study deals with the Fe65.5Cr4Mo4Ga4P12C5B5.5 ferromagnetic bulk amorphous alloy. XRD analysis showed an amorphous structure of the as-cast sample. The same method revealed that, after annealing at 973 K for v=10 min, the sample displayed a crystalline structure with crystalline phases formed. The crystallization process of the alloy was examined by DTA analysis. It was shown that crystallization took place in the temperature range between 810 K and 860 K with the exo-maximum peak temperature at 846 K with a heating rate of 20 K.min-1. The method also showed that, at temperatures ranging from 753 K to 810 K, the alloy exhibited the properties of supercooled liquids. A correlation between heat-induced structural changes and magnetic properties of the alloy was determined by thermomagnetic measurements. Maximum magnetization M=3.7 Am2.kg-1 of the alloy was reached after its annealing at 733 K for τ=10 min. Upon annealing, the alloy exhibited a relaxed amorphous structure. Annealing the alloy above the crystallization temperature led to a decrease in bulk magnetization. After annealing at 973 K for r=10 min, the bulk magnetization of the alloy was M＇=0.45 Am2.kg-1. Accordingly, after crystallization and formation of new compounds, the magnetization of the alloy was decreased by a factor of about 7.7. The strength of the magnetic field applied during the measurements was H=10 kA.m-1. The samples were tested for changes in the microstructure and hardness of both the amorphous phase and the resulting crystalline phase.展开更多
The high-efficient degrading ability of Fe BC amorphous ribbons toward acid orange 7(AO7)via redox reactions is reported and compared with that of Fe PC amorphous ribbons.The time required for degrading50%of AO7 using...The high-efficient degrading ability of Fe BC amorphous ribbons toward acid orange 7(AO7)via redox reactions is reported and compared with that of Fe PC amorphous ribbons.The time required for degrading50%of AO7 using Fe BC amorphous ribbons is only 1/3 of that using Fe PC amorphous ribbons.In the Fe BC amorphous matrix,galvanic cell structures are formed between the Fe-B and Fe-C bonds because of the large difference in their bonding strengths,which contributes to the low reaction activation energy and the high degrading efficiency of Fe BC amorphous ribbons.The extremely long service life of Fe BC amorphous ribbons comes from the progressive formation of 3 D porous nanosheet networks that allow more efficient mass transport and a larger specific surface area.The Fe BC amorphous ribbons show a satisfying degrading ability in not only acidic but also neutral and weak alkaline AO7 solutions.This work provides an effective and environmental-friendly material for degrading azo dyes.展开更多
The deformation behavior of a TiZr-based bulk metallic glass composite(BMGC)was characterized in the supercooled liquid region(SLR)from 623 K to 693 K.It was observed that the alloy exhibits the deformation behavior f...The deformation behavior of a TiZr-based bulk metallic glass composite(BMGC)was characterized in the supercooled liquid region(SLR)from 623 K to 693 K.It was observed that the alloy exhibits the deformation behavior from work softening at low temperatures to work hardening at high temperatures.The yield stress and overshoot stress decrease remarkably with the increase of temperature,accompanied by superplasticity.The results showed that the crystallization occurred in the amorphous matrix for the post-deformation samples and the volume fraction of the corresponding crystallization products increased with increasing testing temperature.It is implied that the work hardening behavior was closely associated with the crystallization of the amorphous matrix.The tensile stress can accelerate the crystallization of amorphous matrix and the martensitic transformation of dendrite phases,which implies that the thermal stability of the alloy decreases under tension.These findings shed light on designing new BMGCs with high mechanical performance as well as the good SLR formability.展开更多
The dye degradation capability and reusability of FeSiBNbCu amorphous ribbons are largely enhanced due to the surface activation by ball milling.The time required for degrading 50%of acid orange 7 solution by the acti...The dye degradation capability and reusability of FeSiBNbCu amorphous ribbons are largely enhanced due to the surface activation by ball milling.The time required for degrading 50%of acid orange 7 solution by the activated FeSiBNbCu amorphous ribbons is only 1/6 of that by the as-quenched ribbons,while the reusable times of the activated ribbons is 6 times larger than that of the as-quenched ribbons.The superior degradation capability and better reusability of the activated FeSiBNbCu amorphous ribbons come from not only the uneven topography of the ribbon surface induced by ball milling,but also the stored deformation energy,including the structural rejuvenation and the enlarged residual stress.The structural rejuvenation in the activated FeSiBNbCu amorphous ribbons is verified by heat relaxation analysis,and the increased residual stress is confirmed by the magnetic domain measurements on the ribbon surfaces.Besides,the environmental adaptability of the activated FeSiBNbCu amorphous ribbons is also investigated.The possible pathways for degradation of acid orange 7 using the activated ribbons,including azo bond cleavage and hydroxylation of benzene ring,are proposed.This work provides a new method to effectively improve the degradation performance of amorphous ribbons.展开更多
So far,some investigations related to the corrosion mechanism of Zr-based metallic glasses in solutions containing Cl-have been developed.However,few attentions have been paid to the situation in F--containing solutio...So far,some investigations related to the corrosion mechanism of Zr-based metallic glasses in solutions containing Cl-have been developed.However,few attentions have been paid to the situation in F--containing solution.This paper describes the corrosion behaviours of Zr52Al10Ni6Cu32 bulk metallic glass(BMG)in Na F and Na Cl aqueous solutions.The corrosion mechanism of Zr-based BMG in F–containing solution was proposed for the first time.It was found that in Na Cl solutions,Zr-based BMG samples underwent typical pitting corrosion.Selective dissolution of Zr,Al and enrichment of Cu were observed in corrosion pits.However,corrosion occurred in the form of general breakdown of passive film in Na F solutions.Such difference is interpreted in terms of the binding ability of anions to surrounding molecules,i.e.,Cl-with loose surrounding water passes through the passive film to cause pitting;F-with a tight surrounding molecules layer absorbs on passive film then coordinates with cations from matrix.展开更多
High-temperature structural metals remain in high demand for aerospace aircraft,gas turbine engines,and nuclear power plants.Refractory high-entropy alloys(RHEAs)with superior mechanical properties at elevated tempera...High-temperature structural metals remain in high demand for aerospace aircraft,gas turbine engines,and nuclear power plants.Refractory high-entropy alloys(RHEAs)with superior mechanical properties at elevated temperatures are promising candidates for high-temperature structural materials.In this work,a WTaMoNbTi RHEA with adequate room temperature plasticity and considerable strength at 1600℃was fabricated by vacuum arc-melting.The room temperature fracture strain of the as-cast WTaMoNbTi RHEA was 7.8%,which was about 5.2 times that of the NbMoTaW alloy.The alloy exhibited a strong resistance to high-temperature softening,with a high yield strength of 173 MPa and compressive strength of 218 MPa at 1600℃.The WTaMoNbTi RHEA possessed excellent phase stability in the range of room temperature to 2000℃.The dendritic grains grew into equiaxed grains after compression test at 1600℃due to the dynamic recrystallization process at high temperature.This work presents a promising high-temperature structural material that can be applied at 1600℃.展开更多
The correlation betweent deformation behavior and atomic-scale heterogeneity of bulk metallic glasses(BMGs)is critical to understand the BMGs'deformation mechanism.In this work,three typical[(Fe_(0.5)Co_(0.5))_(0....The correlation betweent deformation behavior and atomic-scale heterogeneity of bulk metallic glasses(BMGs)is critical to understand the BMGs'deformation mechanism.In this work,three typical[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_4,Fe_(39)Ni_(39)B_(14.2)Si_(2.75)P_(2.75)Nb_(2.3),and Fe_(50)Ni_(30)P_(13)C_(7)BMGs exhibiting different plasticity were selected,and the correlation between deformation behavior and atomic-scale heterogeneity of Fe-based BMGs was studied.It is found that the serrated flow dynamics of Fe-based BMGs transform from chaotic state to self-organized critical state with increasing plasticity.This transformation is attributed to the increasing atomic-scale heterogeneity caused by the increasing free volume and short-to-medium range order,which facilitates a higher frequency of interaction and multiplication of shear bands,thereby results in a brittle to ductile transition in Fe-based BMGs.This work provides new evidence on heterogeneity in plastic Fe-based BMGs from the aspects of atomic-scale structure,and provides new insight into the plastic deformation of Fe-based BMGs.展开更多
The effects of cryogenic thermal cycling on deformation behaviour and structural variation of{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1) bulk metallic glass(BMG)were studied and compared wi...The effects of cryogenic thermal cycling on deformation behaviour and structural variation of{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1) bulk metallic glass(BMG)were studied and compared with Cufree[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4) BMG.After thermal-cycled treatment between 393 K and cryogenic temperature,the{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1)BMG obtained a plastic strain of 7.4%combined with a high yield strength of 4350 MPa.The excellent soft magnetic properties were maintained after CTC treatment.The minor addition of Cu element results in an initial nano-sized heterogeneity in the matrix,which facilitates the rejuvenation process during thermal cycling,and brings to a low optimal thermal temperature of 393 K,making the{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1) BMG more attractive in industrial application.During thermal cycling,the formation of more soft regions leads to the increase of structural heterogeneities,which is beneficial to the initiation of shear transition zones and the formation of multiple shear bands,and thus results in the enhancement of plasticity.This study links the subtle variation of specific structure with macroscopic mechanical properties,and provides a new insight of composition selection for cryogenic thermal cycling treatment.展开更多
In assessing the relationship between calcium supplementation and maintaining bone mass or reducing the risk of fracture, the effectiveness of calcium supplementation has never been decisive. Freshwater crayfish rely ...In assessing the relationship between calcium supplementation and maintaining bone mass or reducing the risk of fracture, the effectiveness of calcium supplementation has never been decisive. Freshwater crayfish rely on amorphous calcium carbonate (ACC), an instable polymorph of calcium carbonate, as the main mineral in the exoskeleton and in the temporary storage organ, the gastrolith. Inspired by the crayfish model, we have previously shown an increase in calcium bioavailability in rats administered with synthetic stable ACC vs. crystalline calcium carbonate (CCC). The current study compared the effects of amorphous calcium derived from either gastrolith or synthetic ACC with those of crystalline calcium, found in commercial CCC or calciumcitrate supplements, in a bone loss prevention model. Rats were subjected to either sham or ovariectomy (OVX) operation (n^20/ group) followed by administration of food pellets supplemented with 0.5% calcium from either source over 12 weeks. Micro-computed tomography (μCT) and histomorphometric analyses revealed bone loss prevention by both gastrolith and ACC treatments, manifested by an increase in morphometric bone parameters, compared to both CCC-?and calcium citrate-treated groups. Both gastrolith and ACC treatments resulted in bone formation in the tibia cancellous bone, indicated by dynamic histomorphometry parameters, compared to either the CCC or calcium citrate treatments. Levels of urine deoxypyridinoline (DPD), suggested an anti-resorptive effect of ACC, which was also the only treatment that led to a significant increase in vertebral mechanical strength, as supported by μCT analysis of topology and orientation parameters of the vertebral trabeculae. To our knowledge, such levels of bone loss prevention by calcium supplements have never been reported. These findings thus suggest the potential of both natural (crayfish gastrolith) and, to a greater extent, synthetic ACC sources for the prevention of metabolic bone disorders and possibly of osteoporotic processes.展开更多
Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the a...Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the addition of Mo on microstructure and mechanical properties of the Mo-free parent alloy is lacking.In this work,we consider five(Co_(37.7)Cr_(24.4)Ni_(37.9))_(100-x)Mo_(x)(x=0,0.7,2.0,3.2,and 6.2)alloys,and reveal that yield/tensile strength and ductility are continuously increased for these alloys with increasing Mo content while a single-phase face-centered cubic structure remains unchanged.It is found that strong solid solution strengthening(SSS)is a main domain to the improved yield strength,whereas grain boundaries are found to soften by the Mo addition.The first-principles calculations demonstrate that a severe local lattice distortion contributes to the enhanced SSS,and the grain boundary softening effect is mostly associated with the decreased shear modulus.Both first-principles calculations and scanning transmission electron microscopy observations reveal that the stacking fault energy(SFE)reduces by the Mo addition.The calculated SFE value decreases from 0.4 mJ/m^(2) to-11.8 mJ/m^(2) at 0 K as Mo content increases from 0 at.%to 6.2 at.%,and experimentally measured values of SFE at room temperature for both samples are about 18 mJ/m^(2) and 9 mJ/m^(2),respectively.The reduction of SFE promoted the generation of stacking faults and deformation twins,which sustain a high strain hardening rate,thus postponing necking instability and enhancing tensile strength and elongation.展开更多
The strength and plasticity of Fe_(39)Ni_(39)B_(12.82)Si_(2.75)Nb_(2.3)P_(4.13)bulk metallic glass(BMG)are improved simultaneously by modulating atomic-scale structure through fluxing treatment.The compression strengt...The strength and plasticity of Fe_(39)Ni_(39)B_(12.82)Si_(2.75)Nb_(2.3)P_(4.13)bulk metallic glass(BMG)are improved simultaneously by modulating atomic-scale structure through fluxing treatment.The compression strength increases from 3074 to 4220 MPa,and the plastic strain is enlarged from 10.7%to more than 50%.The increased mechanical properties of the fluxed Fe Ni BSi Nb P BMG originate from the optimization of atomic-scale structure.More icosahedral-like clusters(ILCs)and crystal-like clusters(CLCs)are found in this Fe Ni-based BMG with fluxing treatment,and the ILCs are usually surrounded by CLCs.Furthermore,phase separation and a sandwich-like heterogeneous structure of SB are also observed during deformation,indicating the multiscale deformation mechanism and a stable shear-band evolution.The unique"ILC surrounded by CLCs"structure and phase separation lead to a stable plastic deformation process with strong interactions of multiple shear bands,thereby the improved plasticity and strength.This work provides useful guidelines to develop strong and plastic Fe-based BMGs from a structural aspect.展开更多
Multicomponent alloys of Zr_(50)M_(50),Zr_(50)(M,Ag)_(50)and Zr_(50)(M,Pd)_(50)(M=Fe,Co,Ni,Cu)can be melt-spun to obtain amorphous ribbons.The maximum thickness for fully amorphous ribbons varies with composition in t...Multicomponent alloys of Zr_(50)M_(50),Zr_(50)(M,Ag)_(50)and Zr_(50)(M,Pd)_(50)(M=Fe,Co,Ni,Cu)can be melt-spun to obtain amorphous ribbons.The maximum thickness for fully amorphous ribbons varies with composition in the range 34-53μm.In contrast,fully amorphous ribbons are not obtainable for binary Zr_(50)Ni_(50)or ternary Zr_(50)(Ni,Cu)_(50)alloys.Heating-induced crystallization occurs through:two stages of amorphous[am]→[~(am')+B2]→[B2+B33]for Zr_(50)M_(50);and[am]→[am'+B2]→[B2+AgZr]for Zr_(50)(M,Ag)_(50);and a single stage of[am]→[B2]for Zr_(50)(M,Pd)_(50),while no B2 phase is formed for the binary and ternary Zr_(50)Q_(50)(Q=Ni or/and Cu)alloys.As-spun amorphous ribbons have good bending plasticity.Remarkably,Zr_(50)M_(50)ribbons in tension show 0.22-0.28%plastic elongation and work-hardening(the yield stress is~820 MPa,the fracture stress is~1200 MPa).When cold-rolled at room temperature to 30%reduction in thickness,Zr_(50)M_(50)ribbons show 10%increase in hardness,while retaining good bending plasticity.Cold-rolling induces precipitation of spheroidal B2 and irregular B33 particles,while deformation in tension induces B2,B33 and also plate-like monoclinic precipitates.The B2 and B33 particles form by polymorphic transformation,and include a high density of internal defects.This novel deformationinduced precipitation has not been recognized for any Zr_(50)Q_(50)binary or ternary alloys.The new multicomponent systems are encouraging for future progress as structural amorphous alloys.展开更多
Liquid dynamics plays an essential role in glass formation.Here we observed a distinct change of liquid dynamics in Gd_(55)Co_(20)Al_(25)metallic glass induced by microalloying Si element.In the equilibrium melt,minor...Liquid dynamics plays an essential role in glass formation.Here we observed a distinct change of liquid dynamics in Gd_(55)Co_(20)Al_(25)metallic glass induced by microalloying Si element.In the equilibrium melt,minor Si(0.5 at.%)addition leads to a more fragile liquid behavior and a smaller strength of liquid-liquid transition with the transition strength(F)decreasing from 0.76 to 0.35.However,in the supercooled liquid,Si-doped liquid exhibits a remarkable enhanced fragile-to-strong transition(FST),and the value of FST factor f increases sharply from 1.63 to 3.84,resulting in a stronger liquid behavior and more sluggish crystallization kinetics for Gd_(55)Co_(20)Al_(24.5)Si_(0.5)metallic glass.Moreover,minor Si addition promotes the formation of a crystal-like structure with a size of 1-2 nm.The interactions between the crystal-like structures and other local favored clusters frustrate the further growth of crystal-like phases,thus stabilizes the amorphous structure.As a result,the glass-forming ability(GFA)was largely improved.The critical diameter of Gd_(55)Co_(20)Al_(25)metallic glass increased from 2 to 7 mm with 0.5 at.%Si addition without deterioration of the magnetocaloric effect.This study provides valuable insight for understanding the distinct effect of microalloying on GFA of metallic glasses from the aspect of the evolution of the liquid.展开更多
The Fe_(81.3)Si_(4)B_(13–x)PxCu_(1.7) soft magnetic alloys with high Cu and proper P elements addition were synthesized with the aim of ensuring the amorphous forming ability(AFA)while expanding the crystallization w...The Fe_(81.3)Si_(4)B_(13–x)PxCu_(1.7) soft magnetic alloys with high Cu and proper P elements addition were synthesized with the aim of ensuring the amorphous forming ability(AFA)while expanding the crystallization window(CW).It is found that the atomic ratio of P/Cu of∼3 is advantageous for AFA whereas a small amount of P addition promotes the precipitation ofα-Fe grains and excessive P addition induces surface crystallization behavior of the present alloys.High Cu concentration can expand the annealing temperature(Ta)window whereas proper P addition effectively expands the annealing time(ta)window.The Fe_(81.3)Si_(4)B_(13-x)PxCu_(1.7) soft magnetic alloy was successfully synthesized with a large Ta window of up to 130°C and ta window of 90 min,which is a breakthrough for nanocrystalline alloys with high saturation magnetization.Microstructure analysis reveals that the ultra-wide CW is related to the unique nucleation mechanism,that is,theα-Fe grains are precipitated attaching to the Cu or CuP clusters and enveloping the Cu clusters,resulting in the high number density ofα-Fe nanocrystals.The ultra-wide CW promises the potential material in flexibly choosing the annealing process according to the performance.展开更多
The mechanical properties, thermodynamic features and their correlation were studied for La-Ce-Ni-Cu-Al high-entropy bulk metallic glasses （HE-BMGs）. Compressive testing indicated that the HE-BMGs are ductile on a m...The mechanical properties, thermodynamic features and their correlation were studied for La-Ce-Ni-Cu-Al high-entropy bulk metallic glasses （HE-BMGs）. Compressive testing indicated that the HE-BMGs are ductile on a microscopic scale but brittle on a macroscopic scale, because of the low fragility index rn of the HE-BMGs. In the non-isothermal process, the activation energies for glass transition for these HE-BMGs are the lowest of the known HE-BMGs. Large values of the Avrami exponent n imply that the crystallization process proceeded through three-dimensional growth and with an increasing nucleation rate. The activation energy for glass transition （Eg） is almost proportional to the HE-BMG fracture strength, because a higher Eg is required to dislodge the molecules from the glassy configuration for the HE-BMGs with a high strength. The findings provide unambiguous evidence for the correlation between the mechanical and thermodynamic properties.展开更多
Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the F...Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the Fe-6.5Si-0.02B alloy is FezB with body-centered tetragonal structure, and its nano-hardness is 15.0 GPa which is higher than that of the matrix （- 8.5 GPa）. In the as-cast alloys, most of the intragranular precipitates are coarse lath-like with the length of 5-15 μm and width of 2-5 μm, and the precipitates formed at the grain boundaries are of about 2-3 μm in width. After oil quenching followed by heat treatment at 1100 ℃ for more than 30 min, the precipitates inside grains are refined with a size of several hundred nanometers and the precipitates at the grain boundaries are refined with a size of 〈 1 μm. After compression test, transgranular and intergranular cracks occur in the as-cast alloys with coarse precipitates. For the quenched alloys with fine precipitates, the number of cracks decreases significantly, and no transgranular cracks happen because some cracks are blocked or the propagation direction is changed by grain boundary.展开更多
Empirical linear combination of atomic orbitals(LCAO)calculations are performed to investigate the electronic structure of Sb_(2)Se_(3),Sb_(2)Te_(3),In_(2)Se_(3) and In_(2)Te_(3).The bands of bonding p states are over...Empirical linear combination of atomic orbitals(LCAO)calculations are performed to investigate the electronic structure of Sb_(2)Se_(3),Sb_(2)Te_(3),In_(2)Se_(3) and In_(2)Te_(3).The bands of bonding p states are overlapped with the bands of lone pair states in these materials.The absorption edges of these materials correspond to indirect gap,and the calculation agrees with experimental values.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFB0300502)the National Natural Science Foundation of China (Grant Nos. 51631003, 51401052, 51871237 and 51501037)
文摘Fe(83.2-x)CoxP(10)C6Cu(0.8)(x=0,4,6,8 and 10)alloys with a high amorphous-forming ability and good softmagnetic properties were successfully synthesized.Saturation magnetic flux density(Bs)is effectively enhanced from 1.53 T to 1.61 T for as-quenched alloy by minor Co addition,which is consistent well with the result of the linear relationship between average magnetic moment and magnetic valence.For Cocontained alloys,the value of corecivity(Hc)is mainly determined by magneto-crystalline anisotropy,while effective permeability(μe)is dominated by grain size and average saturation polarization.After proper heat treatment,the Fe(79.2)Co4P(10)C6Cu(0.8)nanocrystalline alloy exhibited excellent soft-magnetic properties including a high Bsof 1.8 T,a low Hcof 6.6 A/m and a highμeof 15,510,which is closely related to the high volume fraction of α-(Fe,Co)grains and refined uniform nanocrystalline microstructure.
文摘Abstract： This study deals with the Fe65.5Cr4Mo4Ga4P12C5B5.5 ferromagnetic bulk amorphous alloy. XRD analysis showed an amorphous structure of the as-cast sample. The same method revealed that, after annealing at 973 K for v=10 min, the sample displayed a crystalline structure with crystalline phases formed. The crystallization process of the alloy was examined by DTA analysis. It was shown that crystallization took place in the temperature range between 810 K and 860 K with the exo-maximum peak temperature at 846 K with a heating rate of 20 K.min-1. The method also showed that, at temperatures ranging from 753 K to 810 K, the alloy exhibited the properties of supercooled liquids. A correlation between heat-induced structural changes and magnetic properties of the alloy was determined by thermomagnetic measurements. Maximum magnetization M=3.7 Am2.kg-1 of the alloy was reached after its annealing at 733 K for τ=10 min. Upon annealing, the alloy exhibited a relaxed amorphous structure. Annealing the alloy above the crystallization temperature led to a decrease in bulk magnetization. After annealing at 973 K for r=10 min, the bulk magnetization of the alloy was M＇=0.45 Am2.kg-1. Accordingly, after crystallization and formation of new compounds, the magnetization of the alloy was decreased by a factor of about 7.7. The strength of the magnetic field applied during the measurements was H=10 kA.m-1. The samples were tested for changes in the microstructure and hardness of both the amorphous phase and the resulting crystalline phase.
基金financially supported by the National Natural Science Foundation of China(Nos.51631003 and 51871054)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20191269)+1 种基金This research used beam line 13-IDD in the Advanced Photon Source(APS)of USAAPS is supported by the Department of Energy(DOE)office of Science(DE-AC02-06CH11357).
文摘The high-efficient degrading ability of Fe BC amorphous ribbons toward acid orange 7(AO7)via redox reactions is reported and compared with that of Fe PC amorphous ribbons.The time required for degrading50%of AO7 using Fe BC amorphous ribbons is only 1/3 of that using Fe PC amorphous ribbons.In the Fe BC amorphous matrix,galvanic cell structures are formed between the Fe-B and Fe-C bonds because of the large difference in their bonding strengths,which contributes to the low reaction activation energy and the high degrading efficiency of Fe BC amorphous ribbons.The extremely long service life of Fe BC amorphous ribbons comes from the progressive formation of 3 D porous nanosheet networks that allow more efficient mass transport and a larger specific surface area.The Fe BC amorphous ribbons show a satisfying degrading ability in not only acidic but also neutral and weak alkaline AO7 solutions.This work provides an effective and environmental-friendly material for degrading azo dyes.
基金supported financially by the National Natural Science Foundation of China(Nos.51790484,51434008 and 51531005)the National Key Research and Development Program(No.2018YFB0703402)+1 种基金Dong Guan Innovative Research Team Program(No.2014607134)Shenyang Amorphous Metal Manufacturing Co.,Ltd.
文摘The deformation behavior of a TiZr-based bulk metallic glass composite(BMGC)was characterized in the supercooled liquid region(SLR)from 623 K to 693 K.It was observed that the alloy exhibits the deformation behavior from work softening at low temperatures to work hardening at high temperatures.The yield stress and overshoot stress decrease remarkably with the increase of temperature,accompanied by superplasticity.The results showed that the crystallization occurred in the amorphous matrix for the post-deformation samples and the volume fraction of the corresponding crystallization products increased with increasing testing temperature.It is implied that the work hardening behavior was closely associated with the crystallization of the amorphous matrix.The tensile stress can accelerate the crystallization of amorphous matrix and the martensitic transformation of dendrite phases,which implies that the thermal stability of the alloy decreases under tension.These findings shed light on designing new BMGCs with high mechanical performance as well as the good SLR formability.
基金supported financially by the National Natural Science Foundation of China(No.51631003)the Natural Science Foundation of Jiangsu Province of China(No.BK20191269)the Fundamental Research Funds for the Central Universities(No.2242019k1G005)。
文摘The dye degradation capability and reusability of FeSiBNbCu amorphous ribbons are largely enhanced due to the surface activation by ball milling.The time required for degrading 50%of acid orange 7 solution by the activated FeSiBNbCu amorphous ribbons is only 1/6 of that by the as-quenched ribbons,while the reusable times of the activated ribbons is 6 times larger than that of the as-quenched ribbons.The superior degradation capability and better reusability of the activated FeSiBNbCu amorphous ribbons come from not only the uneven topography of the ribbon surface induced by ball milling,but also the stored deformation energy,including the structural rejuvenation and the enlarged residual stress.The structural rejuvenation in the activated FeSiBNbCu amorphous ribbons is verified by heat relaxation analysis,and the increased residual stress is confirmed by the magnetic domain measurements on the ribbon surfaces.Besides,the environmental adaptability of the activated FeSiBNbCu amorphous ribbons is also investigated.The possible pathways for degradation of acid orange 7 using the activated ribbons,including azo bond cleavage and hydroxylation of benzene ring,are proposed.This work provides a new method to effectively improve the degradation performance of amorphous ribbons.
基金the National Key Research And Development Program(No.2018YFB0703402)the National Natural Science Foundation of China(Nos.51790484,U1738101and 51801209)+2 种基金the Liao Ning Revitalization Talents Program(Nos.XLYC1802078 and XLYC1807062)the Dong Guan Innovative Research Team Program(No.2014607134)the Natural Science Foundation of Liaoning Province of China(No.20180550338)。
文摘So far,some investigations related to the corrosion mechanism of Zr-based metallic glasses in solutions containing Cl-have been developed.However,few attentions have been paid to the situation in F--containing solution.This paper describes the corrosion behaviours of Zr52Al10Ni6Cu32 bulk metallic glass(BMG)in Na F and Na Cl aqueous solutions.The corrosion mechanism of Zr-based BMG in F–containing solution was proposed for the first time.It was found that in Na Cl solutions,Zr-based BMG samples underwent typical pitting corrosion.Selective dissolution of Zr,Al and enrichment of Cu were observed in corrosion pits.However,corrosion occurred in the form of general breakdown of passive film in Na F solutions.Such difference is interpreted in terms of the binding ability of anions to surrounding molecules,i.e.,Cl-with loose surrounding water passes through the passive film to cause pitting;F-with a tight surrounding molecules layer absorbs on passive film then coordinates with cations from matrix.
基金financially supported by the National Key Research and Development Program of China(Grant No.2018YFC1902400)the National Natural Science Foundation of China(Grant No.51975582)。
文摘High-temperature structural metals remain in high demand for aerospace aircraft,gas turbine engines,and nuclear power plants.Refractory high-entropy alloys(RHEAs)with superior mechanical properties at elevated temperatures are promising candidates for high-temperature structural materials.In this work,a WTaMoNbTi RHEA with adequate room temperature plasticity and considerable strength at 1600℃was fabricated by vacuum arc-melting.The room temperature fracture strain of the as-cast WTaMoNbTi RHEA was 7.8%,which was about 5.2 times that of the NbMoTaW alloy.The alloy exhibited a strong resistance to high-temperature softening,with a high yield strength of 173 MPa and compressive strength of 218 MPa at 1600℃.The WTaMoNbTi RHEA possessed excellent phase stability in the range of room temperature to 2000℃.The dendritic grains grew into equiaxed grains after compression test at 1600℃due to the dynamic recrystallization process at high temperature.This work presents a promising high-temperature structural material that can be applied at 1600℃.
基金supported by the National Natural Science Foundation of China(Grant Nos.51631003 and 51871054)the Fundamental Research Funds for the Central Universities(Grant No.2242019k1G005)supported by the Department of Energy(DOE)Office of Science(DE-AC02-06CH11357)。
文摘The correlation betweent deformation behavior and atomic-scale heterogeneity of bulk metallic glasses(BMGs)is critical to understand the BMGs'deformation mechanism.In this work,three typical[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_4,Fe_(39)Ni_(39)B_(14.2)Si_(2.75)P_(2.75)Nb_(2.3),and Fe_(50)Ni_(30)P_(13)C_(7)BMGs exhibiting different plasticity were selected,and the correlation between deformation behavior and atomic-scale heterogeneity of Fe-based BMGs was studied.It is found that the serrated flow dynamics of Fe-based BMGs transform from chaotic state to self-organized critical state with increasing plasticity.This transformation is attributed to the increasing atomic-scale heterogeneity caused by the increasing free volume and short-to-medium range order,which facilitates a higher frequency of interaction and multiplication of shear bands,thereby results in a brittle to ductile transition in Fe-based BMGs.This work provides new evidence on heterogeneity in plastic Fe-based BMGs from the aspects of atomic-scale structure,and provides new insight into the plastic deformation of Fe-based BMGs.
基金supported by the National Natural Science Foundation of China(Grant Nos.51631003 and 51871054)the Fundamental Research Funds for the Central Universities(Grant Nos.2242019k1G005 and 2242019K40183)。
文摘The effects of cryogenic thermal cycling on deformation behaviour and structural variation of{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1) bulk metallic glass(BMG)were studied and compared with Cufree[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4) BMG.After thermal-cycled treatment between 393 K and cryogenic temperature,the{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1)BMG obtained a plastic strain of 7.4%combined with a high yield strength of 4350 MPa.The excellent soft magnetic properties were maintained after CTC treatment.The minor addition of Cu element results in an initial nano-sized heterogeneity in the matrix,which facilitates the rejuvenation process during thermal cycling,and brings to a low optimal thermal temperature of 393 K,making the{[(Fe_(0.5)Co_(0.5))_(0.75)B_(0.2)Si_(0.05)]_(96)Nb_(4)}_(99.9)Cu_(0.1) BMG more attractive in industrial application.During thermal cycling,the formation of more soft regions leads to the increase of structural heterogeneities,which is beneficial to the initiation of shear transition zones and the formation of multiple shear bands,and thus results in the enhancement of plasticity.This study links the subtle variation of specific structure with macroscopic mechanical properties,and provides a new insight of composition selection for cryogenic thermal cycling treatment.
文摘In assessing the relationship between calcium supplementation and maintaining bone mass or reducing the risk of fracture, the effectiveness of calcium supplementation has never been decisive. Freshwater crayfish rely on amorphous calcium carbonate (ACC), an instable polymorph of calcium carbonate, as the main mineral in the exoskeleton and in the temporary storage organ, the gastrolith. Inspired by the crayfish model, we have previously shown an increase in calcium bioavailability in rats administered with synthetic stable ACC vs. crystalline calcium carbonate (CCC). The current study compared the effects of amorphous calcium derived from either gastrolith or synthetic ACC with those of crystalline calcium, found in commercial CCC or calciumcitrate supplements, in a bone loss prevention model. Rats were subjected to either sham or ovariectomy (OVX) operation (n^20/ group) followed by administration of food pellets supplemented with 0.5% calcium from either source over 12 weeks. Micro-computed tomography (μCT) and histomorphometric analyses revealed bone loss prevention by both gastrolith and ACC treatments, manifested by an increase in morphometric bone parameters, compared to both CCC-?and calcium citrate-treated groups. Both gastrolith and ACC treatments resulted in bone formation in the tibia cancellous bone, indicated by dynamic histomorphometry parameters, compared to either the CCC or calcium citrate treatments. Levels of urine deoxypyridinoline (DPD), suggested an anti-resorptive effect of ACC, which was also the only treatment that led to a significant increase in vertebral mechanical strength, as supported by μCT analysis of topology and orientation parameters of the vertebral trabeculae. To our knowledge, such levels of bone loss prevention by calcium supplements have never been reported. These findings thus suggest the potential of both natural (crayfish gastrolith) and, to a greater extent, synthetic ACC sources for the prevention of metabolic bone disorders and possibly of osteoporotic processes.
基金financially supported by the Young Scientists Fund of the National Natural Science Foundation of China(No.52001120)the Hunan Provincial National Science Fund for Distin-guished Young Scholars(No.2022JJ10015)+2 种基金the State Key Labora-tory of Advanced Metals and Materials(No.2021-Z09)the Univer-sity of Science&Technology Beijing,China.X.Q.Li was supported by the Swedish Research Council(No.2020-03736)funded by the Swedish Research Council through grant agreement(No.2018-05973)。
文摘Molybdenum(Mo)has been recognized as an essential alloying element of the MP35N(Co_(35.4)Cr_(22.9)Ni_(35.5)Mo_(6.2),at.%)superalloy for enhancing strength and corrosion resistance.However,a full understanding of the addition of Mo on microstructure and mechanical properties of the Mo-free parent alloy is lacking.In this work,we consider five(Co_(37.7)Cr_(24.4)Ni_(37.9))_(100-x)Mo_(x)(x=0,0.7,2.0,3.2,and 6.2)alloys,and reveal that yield/tensile strength and ductility are continuously increased for these alloys with increasing Mo content while a single-phase face-centered cubic structure remains unchanged.It is found that strong solid solution strengthening(SSS)is a main domain to the improved yield strength,whereas grain boundaries are found to soften by the Mo addition.The first-principles calculations demonstrate that a severe local lattice distortion contributes to the enhanced SSS,and the grain boundary softening effect is mostly associated with the decreased shear modulus.Both first-principles calculations and scanning transmission electron microscopy observations reveal that the stacking fault energy(SFE)reduces by the Mo addition.The calculated SFE value decreases from 0.4 mJ/m^(2) to-11.8 mJ/m^(2) at 0 K as Mo content increases from 0 at.%to 6.2 at.%,and experimentally measured values of SFE at room temperature for both samples are about 18 mJ/m^(2) and 9 mJ/m^(2),respectively.The reduction of SFE promoted the generation of stacking faults and deformation twins,which sustain a high strain hardening rate,thus postponing necking instability and enhancing tensile strength and elongation.
基金the National Natural Science Foundation of China(Grant Nos.51631003 and 51871054)the Fundamental Research Funds for the Central Universities(Grant Nos.2242019k1G005 and 2242019K40183)the Department of Energy(DOE)Office of Science(DE-AC02-06CH11357)。
文摘The strength and plasticity of Fe_(39)Ni_(39)B_(12.82)Si_(2.75)Nb_(2.3)P_(4.13)bulk metallic glass(BMG)are improved simultaneously by modulating atomic-scale structure through fluxing treatment.The compression strength increases from 3074 to 4220 MPa,and the plastic strain is enlarged from 10.7%to more than 50%.The increased mechanical properties of the fluxed Fe Ni BSi Nb P BMG originate from the optimization of atomic-scale structure.More icosahedral-like clusters(ILCs)and crystal-like clusters(CLCs)are found in this Fe Ni-based BMG with fluxing treatment,and the ILCs are usually surrounded by CLCs.Furthermore,phase separation and a sandwich-like heterogeneous structure of SB are also observed during deformation,indicating the multiscale deformation mechanism and a stable shear-band evolution.The unique"ILC surrounded by CLCs"structure and phase separation lead to a stable plastic deformation process with strong interactions of multiple shear bands,thereby the improved plasticity and strength.This work provides useful guidelines to develop strong and plastic Fe-based BMGs from a structural aspect.
基金support from the Recruitment Program of Global Experts“1000 Talents Plan”(Grant No.WQ20121200052)the National Natural Science Foundation of China(Grant No.51771131)+2 种基金the Deanship of Scientific Research(DSR),at King Abdulaziz University,Jeddah,Saudi Arabia funded this project,under Grant No.(FP-101-42)the Ministry of Education and Science of the Russian Federation in the framework of the program aimed to increase the competitiveness of the National University of Science and Technology,“MISiS”(Grant No.K2-2019-002)support from the European Research Council under the European Union’s Horizon 2020 research and innovation program(Grant No.ERC-2015-Ad G-695487:Extend Glass)。
文摘Multicomponent alloys of Zr_(50)M_(50),Zr_(50)(M,Ag)_(50)and Zr_(50)(M,Pd)_(50)(M=Fe,Co,Ni,Cu)can be melt-spun to obtain amorphous ribbons.The maximum thickness for fully amorphous ribbons varies with composition in the range 34-53μm.In contrast,fully amorphous ribbons are not obtainable for binary Zr_(50)Ni_(50)or ternary Zr_(50)(Ni,Cu)_(50)alloys.Heating-induced crystallization occurs through:two stages of amorphous[am]→[~(am')+B2]→[B2+B33]for Zr_(50)M_(50);and[am]→[am'+B2]→[B2+AgZr]for Zr_(50)(M,Ag)_(50);and a single stage of[am]→[B2]for Zr_(50)(M,Pd)_(50),while no B2 phase is formed for the binary and ternary Zr_(50)Q_(50)(Q=Ni or/and Cu)alloys.As-spun amorphous ribbons have good bending plasticity.Remarkably,Zr_(50)M_(50)ribbons in tension show 0.22-0.28%plastic elongation and work-hardening(the yield stress is~820 MPa,the fracture stress is~1200 MPa).When cold-rolled at room temperature to 30%reduction in thickness,Zr_(50)M_(50)ribbons show 10%increase in hardness,while retaining good bending plasticity.Cold-rolling induces precipitation of spheroidal B2 and irregular B33 particles,while deformation in tension induces B2,B33 and also plate-like monoclinic precipitates.The B2 and B33 particles form by polymorphic transformation,and include a high density of internal defects.This novel deformationinduced precipitation has not been recognized for any Zr_(50)Q_(50)binary or ternary alloys.The new multicomponent systems are encouraging for future progress as structural amorphous alloys.
基金the National Natural Science Foundation of China(Nos.51631003,51571131,51971061 and 51471050)the National Key Research Program of China(No.2016YFB0300500)。
文摘Liquid dynamics plays an essential role in glass formation.Here we observed a distinct change of liquid dynamics in Gd_(55)Co_(20)Al_(25)metallic glass induced by microalloying Si element.In the equilibrium melt,minor Si(0.5 at.%)addition leads to a more fragile liquid behavior and a smaller strength of liquid-liquid transition with the transition strength(F)decreasing from 0.76 to 0.35.However,in the supercooled liquid,Si-doped liquid exhibits a remarkable enhanced fragile-to-strong transition(FST),and the value of FST factor f increases sharply from 1.63 to 3.84,resulting in a stronger liquid behavior and more sluggish crystallization kinetics for Gd_(55)Co_(20)Al_(24.5)Si_(0.5)metallic glass.Moreover,minor Si addition promotes the formation of a crystal-like structure with a size of 1-2 nm.The interactions between the crystal-like structures and other local favored clusters frustrate the further growth of crystal-like phases,thus stabilizes the amorphous structure.As a result,the glass-forming ability(GFA)was largely improved.The critical diameter of Gd_(55)Co_(20)Al_(25)metallic glass increased from 2 to 7 mm with 0.5 at.%Si addition without deterioration of the magnetocaloric effect.This study provides valuable insight for understanding the distinct effect of microalloying on GFA of metallic glasses from the aspect of the evolution of the liquid.
基金supported by the National Natural Science Foundation of China(No.51871237)the Natural Science Foundation of Jiangsu Province(No.BK20201282)Atom probe tomography research was conducted at the Inter-University 3D Atom Probe Tomography Unit of City University of Hong Kong supported by the CityU(No.9360161).
文摘The Fe_(81.3)Si_(4)B_(13–x)PxCu_(1.7) soft magnetic alloys with high Cu and proper P elements addition were synthesized with the aim of ensuring the amorphous forming ability(AFA)while expanding the crystallization window(CW).It is found that the atomic ratio of P/Cu of∼3 is advantageous for AFA whereas a small amount of P addition promotes the precipitation ofα-Fe grains and excessive P addition induces surface crystallization behavior of the present alloys.High Cu concentration can expand the annealing temperature(Ta)window whereas proper P addition effectively expands the annealing time(ta)window.The Fe_(81.3)Si_(4)B_(13-x)PxCu_(1.7) soft magnetic alloy was successfully synthesized with a large Ta window of up to 130°C and ta window of 90 min,which is a breakthrough for nanocrystalline alloys with high saturation magnetization.Microstructure analysis reveals that the ultra-wide CW is related to the unique nucleation mechanism,that is,theα-Fe grains are precipitated attaching to the Cu or CuP clusters and enveloping the Cu clusters,resulting in the high number density ofα-Fe nanocrystals.The ultra-wide CW promises the potential material in flexibly choosing the annealing process according to the performance.
文摘The mechanical properties, thermodynamic features and their correlation were studied for La-Ce-Ni-Cu-Al high-entropy bulk metallic glasses （HE-BMGs）. Compressive testing indicated that the HE-BMGs are ductile on a microscopic scale but brittle on a macroscopic scale, because of the low fragility index rn of the HE-BMGs. In the non-isothermal process, the activation energies for glass transition for these HE-BMGs are the lowest of the known HE-BMGs. Large values of the Avrami exponent n imply that the crystallization process proceeded through three-dimensional growth and with an increasing nucleation rate. The activation energy for glass transition （Eg） is almost proportional to the HE-BMG fracture strength, because a higher Eg is required to dislodge the molecules from the glassy configuration for the HE-BMGs with a high strength. The findings provide unambiguous evidence for the correlation between the mechanical and thermodynamic properties.
基金This research was funded by the Major States Basic Research Development Program of China （973 Program, No. 2011CB606300） and China Postdoctoral Science Foundation （Nos. 2012M520263 and 2013T60110）.
文摘Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the Fe-6.5Si-0.02B alloy is FezB with body-centered tetragonal structure, and its nano-hardness is 15.0 GPa which is higher than that of the matrix （- 8.5 GPa）. In the as-cast alloys, most of the intragranular precipitates are coarse lath-like with the length of 5-15 μm and width of 2-5 μm, and the precipitates formed at the grain boundaries are of about 2-3 μm in width. After oil quenching followed by heat treatment at 1100 ℃ for more than 30 min, the precipitates inside grains are refined with a size of several hundred nanometers and the precipitates at the grain boundaries are refined with a size of 〈 1 μm. After compression test, transgranular and intergranular cracks occur in the as-cast alloys with coarse precipitates. For the quenched alloys with fine precipitates, the number of cracks decreases significantly, and no transgranular cracks happen because some cracks are blocked or the propagation direction is changed by grain boundary.
文摘Empirical linear combination of atomic orbitals(LCAO)calculations are performed to investigate the electronic structure of Sb_(2)Se_(3),Sb_(2)Te_(3),In_(2)Se_(3) and In_(2)Te_(3).The bands of bonding p states are overlapped with the bands of lone pair states in these materials.The absorption edges of these materials correspond to indirect gap,and the calculation agrees with experimental values.
