In order to improve the hydrogenation and dehydrogenation performances of the Mg2Ni-type alloys, Mg was partially substituted by La in the alloy, and melt spinning technology was used for the preparation of the Mg20-x...In order to improve the hydrogenation and dehydrogenation performances of the Mg2Ni-type alloys, Mg was partially substituted by La in the alloy, and melt spinning technology was used for the preparation of the Mg20-xLaxNi10 (x=0, 2, 4, 6) hydrogen storage alloys. The structures of the alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). It was found that no amorphous phase formed in the as-spun La-free alloy, but the as-spun alloys containing La held a major amorphous phase. When La content x≤2, the major phase in the as-cast alloys was Mg2Ni phase, but with further increase of La content, the major phase of the as-cast alloys changed into LaNi5+LaMg3 phase. Thermal stability of the as-spun alloys was studied by differential scanning calorimetry (DSC), showing that spinning rate was a negligible factor on the crystallization temperature of the amorphous phase. The hydrogen absorption and desorption kinetics of the as-cast and as-spun alloys were measured using an automatically controlled Sieverts apparatus, confirming that the hydrogen absorption and desorption capacities and kinetics of the as-cast alloys clearly increased with rising La content. For La content x=2, the as-spun alloy displayed optimal hydrogen desorption kinetics at 200 ℃.展开更多
Six samples of linear high randomness 60PHB/ PET thermotropic liquid crystal copolyesters are made by melt copolymerization at 290℃ , whose randomness about 0.955 is measured by the discernible ’H-NMR spectrometer. ...Six samples of linear high randomness 60PHB/ PET thermotropic liquid crystal copolyesters are made by melt copolymerization at 290℃ , whose randomness about 0.955 is measured by the discernible ’H-NMR spectrometer. High tenacity, high module fiber is prepared by melt spinning in liquid crystal phase. The effect of molecular weight, shear rate, temperature as well as spinning drawn ratio on the mechanical behavior of 60PHB / PET copolyester fiber are shown that, lower shear rate (2<sup> </sup>10 s<sup>-1</sup>), higher temperature melting (300℃ ), lower temperature spinning (280℃ ) and higher molecular weight are favourable to the increase of the fiber mechanical properties. With the variance of drawn ratio, fiber mechanical property has a transition point due to traversion from shear-orientation to drawn-orientation. The copolyester fiber has high crystallinity, high orientation at the crystalline region, high chain orientation and high regular fibrillar structure.展开更多
La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annea...La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annealing is favorable to formation of the A2 B7-type phase and promotes the discharge capacity,cycling stability and high rate discharge ability of the as-spun alloys.Phase constitution of the annealed alloys is found to be closely related to the microstructure of the as-spun alloys.A single phase A2 B7-type microstructure is obtained in the annealed alloy which is attributed to the lower abundance of the LaNis of the original alloy spun with lower cooling rate.Formation of the single phase A2 B7-type microstructure is also ascribed to the isolated and homogeneous distribution of the morphology of the as-spun alloy.The single phase alloy presents higher discharge capacity and better cycling stability compared with other annealed alloys.展开更多
In order to architecturally and functionally mimic native Extracellular Matrix (ECM), a novel micro/nano-fibrous scaffold of hydroxyapetite/poly(lactide-co-glycolide) (HA/PLGA) composite was successfully prepare...In order to architecturally and functionally mimic native Extracellular Matrix (ECM), a novel micro/nano-fibrous scaffold of hydroxyapetite/poly(lactide-co-glycolide) (HA/PLGA) composite was successfully prepared by melt-spinning method. A porous three-dimensional scaffold fabricated by melt-molding particulate-leaching method was used as control. This kind of scaffold comprising both nanofiber and microfiber had an original structure including a nano-network favorable for cell adhe- sion, and a micro-fiber providing a strong skeleton for support. The microfibers and nanofibers were blended homogeneously in scaffold and the compression strength reached to 6.27 MPa, which was close to human trabecular bone. The typical mi- cro/nano-fibrous structure was more benefcial for the proliferation and differentiation of Bone Mesenehymal Stem Cells (BMSCs). The calcium deposition and Alkaline Phosphatase (ALP) activity were evaluated by the differentiation of BMSCs, and the results indicated that the temporary ECM was very beneficial for the differentiation of BMSCs into maturing osteoblasts. For repairing rabbit radius defects in vivo, micro/nano-fibrous scaffold was used for the purpose of rapid bone remodeling in the defect area. The results showed that a distinct bony callus of bridging was observed at 12 weeks post-surgery and the expression of osteogenesis-related genes (bone-morphogenetic protein-2, Osteonectin, collagen-I) increased because of the ECM-like structure. Based on the results, the novel micro/nano-fibrous scaffold might be a promising candidate for bone tissue engi- neering.展开更多
Structure,magnetic properties and ductile of melt-spun Fe_(83-x)Si_(4)B_(13-y)C_(y)Cu_(x)(x=0-1.7;y=0-8)alloys were investigated.The addition of 1.7 at.%Cu in a Fe_(83)Si_(4)B_(13) amorphous alloy generates abundantα...Structure,magnetic properties and ductile of melt-spun Fe_(83-x)Si_(4)B_(13-y)C_(y)Cu_(x)(x=0-1.7;y=0-8)alloys were investigated.The addition of 1.7 at.%Cu in a Fe_(83)Si_(4)B_(13) amorphous alloy generates abundantα-Fe crystals by providing nucleation sites,and further C doping promotes the growth of the crystals by suitable turning amorphous-forming ability,hence they increase saturation magnetic flux density(B_(s))and slightly worse magnetic softness of the as-spun alloys.The as-spun Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy possesses a combined structure of a fully amorphous layer in wheel side surface and predominating nanocrystalline structure with gradually enlargedα-Fe crystal,whose average size and volume fraction are determined as about 12 nm and 32%,respectively,therefore superior soft magnetic properties and ductile with a high B_(s)of 1.74 T,coercivity(H_(c))of 32.7 A/m,effective permeability(μ_(e),at 1 kHz)of 3200 and high relatively strain at fracture(ε_(f))of 3.61%can be achieved directly in this alloy by only using melt-spinning.The annealing at 578 K releases internal stress,promotes the growth of theα-Fe crystals and remains the amorphous layer of the Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy,then improves the soft magnetic properties and maintains the superior ductile with increasing the B_(s)andμ_(e)to 1.80 T and 14,100,respectively,lowering the H_(c)to9.4 A/m and slightly reducing theε_(f)to 2.39%.The combination of superior soft magnetic properties and ductile and simplified synthesis process entitles the Fe-Si-B-C-Cu nanocrystalline alloys great potentials in high performance electromagnetic applications.展开更多
A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis(methylamino)borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine(PBN).This asymmetric alkyl...A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis(methylamino)borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine(PBN).This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine(TCB) with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.展开更多
The reduction diffusion method was performed for the sludge scrap of Nd-Fe-B sintered magnets with adding Ca metal to recover the oxidized Nd-Fe-B phase. After washing the resultant powders to remove Ca metal componen...The reduction diffusion method was performed for the sludge scrap of Nd-Fe-B sintered magnets with adding Ca metal to recover the oxidized Nd-Fe-B phase. After washing the resultant powders to remove Ca metal component, the powders obtained were recycled as an isotropic magnetic powder by the melt spinning method. The magnetic properties of powders as recycled were inferior, especially for the coercivity value, due to the deletion of rare earth metals during the washing process. The adjustment of metal composition, i.e., the addition of Nd metal, at the melt spinning process improved the magnetic properties to be B r=~0.75 T, H cj=~0.93 mA·m -1, and (BH) max=~91 kJ·m -3. The magnetic properties of the bonded magnets prepared from the composition-adjusted powders were B r=~0.66 T, H cj=~0.92 mA·m -1, and (BH) max=~70 kJ·m -3, which are approximately comparable to the commercially available MQPB boned one (B r=~0.73 T, H cj=~0.79 mA·m -1, and (BH) max=~86 kJ·m -3).展开更多
A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt...A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermo-elastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.展开更多
The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets. This review first broadly discusses the...The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets. This review first broadly discusses the principle of cooling control, amorphization, crystallization, annealing, and consolidation of the melt-spun ribbons. The phase, microstructure,and magnetic properties of popular single-phase nanocrystalline magnets are reviewed, followed by the nanocomposite magnets consisting of magnetically hard and soft phases. The precipitation-hardened magnetic materials prepared by melt spinning are also discussed. Finally, the role of intergrain exchange coupling, thermal fluctuation, and reversible/irreversible magnetization processes are discussed and correlated to the magnetic phenomena in both single-phase and nanocomposite magnets.展开更多
The La-Mg-Ni system A2B7-type electrode alloys with nominal composition La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1(x=0,0.05, 0.1,0.15,0.2)were prepared by casting and melt-spinning.The influences of melt spinning on the electro...The La-Mg-Ni system A2B7-type electrode alloys with nominal composition La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1(x=0,0.05, 0.1,0.15,0.2)were prepared by casting and melt-spinning.The influences of melt spinning on the electrochemical performances as well as the structures of the alloys were investigated.The results obtained by XRD,SEM and TEM show that the as-cast and spun alloys have a multiphase structure,consisting of two main phases(La,Mg)Ni3 and LaNi5 as well as a residual phase LaNi2.The melt spinning leads to an obvious increase of the LaNi5 phase and a decrease of the(La,Mg)Ni3 phase in the alloys.The results of the electrochemical measurement indicate that the discharge capacity of the alloys(x≤0.1)first increases and then decreases with the increase of spinning rate,whereas for x>0.1,the discharge capacity of the alloys monotonously falls.The melt spinning slightly impairs the activation capability of the alloys,but it significantly enhances the cycle stability of the alloys.展开更多
Fe-based amorphous alloys with high iron content of 76at%-80at%were synthesized in the Fe-Mo-Si-P-C-B alloy system by the single roller melt-spinning technique.The amorphous ribbons exhibit high Vickers microhardness ...Fe-based amorphous alloys with high iron content of 76at%-80at%were synthesized in the Fe-Mo-Si-P-C-B alloy system by the single roller melt-spinning technique.The amorphous ribbons exhibit high Vickers microhardness and good ductility,which can be indented and bent 180°without breaking.A number of shear bands could be observed around the indents and the bending traces.Studies on the magnetic properties of the amorphous alloys show that they possess high saturation magnetizations of 1.34-1.6 T,which increases with the increase of iron content.The core losses of these Fe-based amorphous alloys at various magnetic inductions were tested and found to be significantly dependent on their components.The Fe-Mo-Si-P-C-B amorphous alloys with excellent mechanical properties and soft magnetic properties have promising potential in functional applications.展开更多
Nd8.5Fe74Co5Cu1Nb1Zr3Cr1B6.5 bonded magnets were prepared by melt-spun and subsequent heat treatment. Magnetic properties of Br=0.68 T,JHc=716 kA/m, (BH)max=77 kJ/m3 were achieved. The addition of Cr element shows to ...Nd8.5Fe74Co5Cu1Nb1Zr3Cr1B6.5 bonded magnets were prepared by melt-spun and subsequent heat treatment. Magnetic properties of Br=0.68 T,JHc=716 kA/m, (BH)max=77 kJ/m3 were achieved. The addition of Cr element shows to be significantly advantageous in reducing grain size and increasing the intrinsic coercivity.展开更多
Sn/Sb based alloy anodes have attracted considerable interest as electrodes for next-generation high performance Li-ion batteries (LIBs) owing to their high theoretical capacities. And fabricate porous structure is an...Sn/Sb based alloy anodes have attracted considerable interest as electrodes for next-generation high performance Li-ion batteries (LIBs) owing to their high theoretical capacities. And fabricate porous structure is an effective way to improve materials’ cycling performance. Here, we developed nanoporous SnSb alloy ribbon (NP-SnSb) through a melt-spinning/chemical-etching process and took it as electrode of LIB directly. Being of self-supported and binder free, the NP-SnSb shows a total outperformance over its nonporous counterparts both in cycling performance and kinetic characteristic. Besides, considering the melt-spinning/chemical-etching synthetic process is high-through-put and simple, the ribbon kind of alloy anodes have strong potential application for LIBs research.展开更多
The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used t...The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used to prepare the La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) electrode alloys. The impacts of the melt spinning and the substituting La with Zr on the structures and the electrochemical hydrogen storage characteristics of the alloys were systemically investigated. The analysis of XRD and TEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning ameliorate the electrochemical cycle stability of the alloys dramatically. Furthermore, the high rate discharge ability (HRD) of the as-spun (10 m/s) alloys notably declines with growing the amount of Zr substitution, while it first augments and then falls for the (x=0.1) alloy with rising the spinning rate.展开更多
The present study reported the influence of heavy rare-earth elements(Gd and/or Dy)on Sm-Co-based melt-spun ribbons.Microstructure and magnetic properties of Sm-Co-based(Sm_(1-x)RE_(x)Co_(5))ternary and quaternary sys...The present study reported the influence of heavy rare-earth elements(Gd and/or Dy)on Sm-Co-based melt-spun ribbons.Microstructure and magnetic properties of Sm-Co-based(Sm_(1-x)RE_(x)Co_(5))ternary and quaternary systems were investigated.The X-ray diffraction,Auger spectroscopy,scanning electron microscopy(SEM)and transmission electron microscopy(TEM)analyses reveal the presence of the 1:5H and 2:17R phases in the as-spun ribbons.A high-temperature magnetic measurement reports a Curie temperature(Tc)at~825 and~869 K in Sm0.6Gd0.4Co5(ribbon A)and Sm_(0.6)Gd_(0.3)Dy_(0.1)Co_(5)(ribbon B),respectively.A low-temperature magnetic measurement on Sm0.6Gd0.3Dy0.1Co5 ribbons exhibits a type-2 SR(spin reorientation)behaviour at~72 K,which arises due to the presence of the DyCo5 phase.Room temperature magnetic measurements reveal that overall magnetic measurement(OMP)is about 24 and 29.9 for ribbons A and B,respectively.Consequently,the comparative investigations profess that ribbon B shows better magnetic performance due to Dy addition with reduced grain size.This observation indicates that the Gd and Dy substituted Sm-Co magnet can be a potential magnet for high-temperature applications.展开更多
A new Al-based amorphous alloy with excellent corrosion resistance and high thermal stability was produced in the Al-Co-RE(Ce-La)system.In this regard,two different amorphous-nanocrystalline ribbons:Al_(87.6)-Co_(6.4)...A new Al-based amorphous alloy with excellent corrosion resistance and high thermal stability was produced in the Al-Co-RE(Ce-La)system.In this regard,two different amorphous-nanocrystalline ribbons:Al_(87.6)-Co_(6.4)-Ce_(3.8-)La_(2.2)(M_(1))and Al_(82.3)-Co_(10.1)-Ce_(4.8)-La_(2.8)(M_(2))were prepared using melt spinning.The results reveal the supercooled liquid region(ATx)of 218℃which shows that the M2alloy has higher thermal stability in comparison to the M1alloy.The M2ribbons present the superior corrosion resistance because of the formation of amorphous phase.The icorr,Ecorr,Epit,and Epit-Ecorrvalues of fully amorphous Al-Co-Ce-La metallic ribbons have a better trend of anti-corrosion performance compared to other crystalline and amorphous aluminum alloys.展开更多
To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Cei7Fe78-xTaxB6 (x = 0-1) alloys, the coercivity H...To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Cei7Fe78-xTaxB6 (x = 0-1) alloys, the coercivity Hc increases from 439 to 553 kA/m with increasing x value from 0 to 0.75. Microstructure characterizations indicate that Ta doping is helpful for grain refinement. A second phase of TaB2 is observed in Ce17Fe77.25Tao.75B6 alloy, which acts as the pinning center of the magnetic domains, resulting in the change of coercivity mechanism from nucleation type to nucleation +pinning type. The micromagnetic simulation confirms that non-magnetic particles within hard magnetic phase can increase the demagnetization field around them and it is crucial for preventing the further magnetization reverse by pinning effect. Take the advantage of Ta doping for enhancing the coercivity, Ce content of Ce-Fe-B alloy can be further cut down to increase the remanence Jr due to the reduced volume fraction of CeFe2 phase and increased Fe/Ce ratio. As a result, a good combination of magnetic properties with Hc = 514 kA/m, Jr = 0.49 T, and the maximum energy product (BH)max = 36 kJ/m^3 have been obtained in Ce15Fe79.25Tao.75B6 alloy. It is expected that the present work can serve as a useful reference for designing new permanent magnetic materials with low-cost.展开更多
The novel A1-5Ti-IB-1RE nanoribbons were synthesized by melt-spinning. The microstructure showed that the A1-5Ti- 1B-1RE nanoribbon consisted of granular-like TiB2 and core-shell-like TiA13/Ti2A120Ce. The A1-5Ti-IB-1R...The novel A1-5Ti-IB-1RE nanoribbons were synthesized by melt-spinning. The microstructure showed that the A1-5Ti- 1B-1RE nanoribbon consisted of granular-like TiB2 and core-shell-like TiA13/Ti2A120Ce. The A1-5Ti-IB-1RE nanoribbon could give rise to the excellent refining effect on as-cast A356 alloys. The refining efficiency and formation mechanism of A1-5Ti-IB-IRE nanoribbons were investigated. In accordance with the experimental results, it could be seen that the A1-5Ti-IB-1RE nanoribbon could maintain the refining effect after 60 min of holding. Additionally, owing to the addition of A1-5Ti-IB-1RE nanoribbon, the mechanical properties of A356 alloys could be enhanced significantly.展开更多
We investigated the structural and magnetic properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. Samples were arc melted then melt spun at 37 m/s up to 55 m/s to obtain ribbon for powdering. Annealing...We investigated the structural and magnetic properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. Samples were arc melted then melt spun at 37 m/s up to 55 m/s to obtain ribbon for powdering. Annealing was performed in argon atmosphere for 30- 75 min at 600-870 oC. In as-spun ribbons the hexagonal SmCo7 (TbCu7-type of structure) of crystal structure was determined from x-ray diffraction patterns, while fcc-Co has been identified as a secondary phase. After annealing, the 1:7 phase of the as-spun ribbons transformed into 2:17 and 1:5 phases. X-ray patterns for as-milled powders exhibited very broad peaks making it difficult to identify a precise structure but repre-sented the 1:7 structure after annealing at low temperature (650 oC). TEM analysis showed a homogeneous nanocrystalline microstructure with average grain size of 30-80 nm. Coercivity values of 15-27 kOe were obtained from hysteresis loops traced up to a field of 5 T. The co-ercivity decreased as temperature increases, but it maintained values higher than 5 kOe at 380 oC. The maximum energy product at room temperature increased, as high as 7.2 MGOe, for melt-spun isotropic ribbons produced at higher wheel speeds. Anisotropic ribbons had a maximum energy product close to 12 MGOe.展开更多
The effect of wheel speed on phase formation and magnetic properties of (Ndo.4La0.6)lsFeTzsBzs and (Ndo.4La0.6)13.4Fe79.9B6.7 ribbons prepared by melt-spinning method was investigated experimentally. Based on X-ra...The effect of wheel speed on phase formation and magnetic properties of (Ndo.4La0.6)lsFeTzsBzs and (Ndo.4La0.6)13.4Fe79.9B6.7 ribbons prepared by melt-spinning method was investigated experimentally. Based on X-ray diffraction results, all melt-spun ribbons consist of the main phase with the tetragonal 2:14:1 type structure and the minor α-Fe phase. Magnetic measurements show the maximum magnetic energy product ((BH)max) and the remanence (Mr) increases firstly and then decreases with the increase of wheel speed, while the coercivity (Hci) increases, resulting from the variation of the average volume fraction of the ^-Fe phase and the average grain size in the melt-spun ribbons. Using Henkel plots, the interaction between the 2:14:1 phase and the ^-Fe phase in the melt-spun ribbons was analyzed and the intergranular exchange coupling is manifested. Optimal magnetic properties of Hci - 7.27 kOe, Mr - 90.94 emu/g and (BH)max -- 12.10 MGOe are achieved in the (Ndo.4La0.6)lsFeTzsBT.s ribbon with the wheel speed of 26 m/s. It indicates that magnetic properties of Nd-Fe-B melt-spun ribbons with highly abundant rare earth element La can be improved by optimizing alloy composition and preparation process.展开更多
基金supported by 863 Program (2006AA05Z132)the National Natural Science Foundations of China (50871050 and 50701011)+1 种基金Natural Science Foundation of Inner Mongolia, China (200711020703)High Education Science Research Project of Inner Mongolia, China (NJzy08071)
文摘In order to improve the hydrogenation and dehydrogenation performances of the Mg2Ni-type alloys, Mg was partially substituted by La in the alloy, and melt spinning technology was used for the preparation of the Mg20-xLaxNi10 (x=0, 2, 4, 6) hydrogen storage alloys. The structures of the alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). It was found that no amorphous phase formed in the as-spun La-free alloy, but the as-spun alloys containing La held a major amorphous phase. When La content x≤2, the major phase in the as-cast alloys was Mg2Ni phase, but with further increase of La content, the major phase of the as-cast alloys changed into LaNi5+LaMg3 phase. Thermal stability of the as-spun alloys was studied by differential scanning calorimetry (DSC), showing that spinning rate was a negligible factor on the crystallization temperature of the amorphous phase. The hydrogen absorption and desorption kinetics of the as-cast and as-spun alloys were measured using an automatically controlled Sieverts apparatus, confirming that the hydrogen absorption and desorption capacities and kinetics of the as-cast alloys clearly increased with rising La content. For La content x=2, the as-spun alloy displayed optimal hydrogen desorption kinetics at 200 ℃.
文摘Six samples of linear high randomness 60PHB/ PET thermotropic liquid crystal copolyesters are made by melt copolymerization at 290℃ , whose randomness about 0.955 is measured by the discernible ’H-NMR spectrometer. High tenacity, high module fiber is prepared by melt spinning in liquid crystal phase. The effect of molecular weight, shear rate, temperature as well as spinning drawn ratio on the mechanical behavior of 60PHB / PET copolyester fiber are shown that, lower shear rate (2<sup> </sup>10 s<sup>-1</sup>), higher temperature melting (300℃ ), lower temperature spinning (280℃ ) and higher molecular weight are favourable to the increase of the fiber mechanical properties. With the variance of drawn ratio, fiber mechanical property has a transition point due to traversion from shear-orientation to drawn-orientation. The copolyester fiber has high crystallinity, high orientation at the crystalline region, high chain orientation and high regular fibrillar structure.
基金Project supported by the National Natural Science Foundation of China(51761032,51501095)the University Foundation of Inner Mongolia(NJZZ18142)Natural Science Foundation of Inner Mongolia(2018MS05040)
文摘La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annealing is favorable to formation of the A2 B7-type phase and promotes the discharge capacity,cycling stability and high rate discharge ability of the as-spun alloys.Phase constitution of the annealed alloys is found to be closely related to the microstructure of the as-spun alloys.A single phase A2 B7-type microstructure is obtained in the annealed alloy which is attributed to the lower abundance of the LaNis of the original alloy spun with lower cooling rate.Formation of the single phase A2 B7-type microstructure is also ascribed to the isolated and homogeneous distribution of the morphology of the as-spun alloy.The single phase alloy presents higher discharge capacity and better cycling stability compared with other annealed alloys.
基金This research was financially supported by Na- tional Natural Science Foundation of China (Projects 51103149, 51273195 and 51321062).
文摘In order to architecturally and functionally mimic native Extracellular Matrix (ECM), a novel micro/nano-fibrous scaffold of hydroxyapetite/poly(lactide-co-glycolide) (HA/PLGA) composite was successfully prepared by melt-spinning method. A porous three-dimensional scaffold fabricated by melt-molding particulate-leaching method was used as control. This kind of scaffold comprising both nanofiber and microfiber had an original structure including a nano-network favorable for cell adhe- sion, and a micro-fiber providing a strong skeleton for support. The microfibers and nanofibers were blended homogeneously in scaffold and the compression strength reached to 6.27 MPa, which was close to human trabecular bone. The typical mi- cro/nano-fibrous structure was more benefcial for the proliferation and differentiation of Bone Mesenehymal Stem Cells (BMSCs). The calcium deposition and Alkaline Phosphatase (ALP) activity were evaluated by the differentiation of BMSCs, and the results indicated that the temporary ECM was very beneficial for the differentiation of BMSCs into maturing osteoblasts. For repairing rabbit radius defects in vivo, micro/nano-fibrous scaffold was used for the purpose of rapid bone remodeling in the defect area. The results showed that a distinct bony callus of bridging was observed at 12 weeks post-surgery and the expression of osteogenesis-related genes (bone-morphogenetic protein-2, Osteonectin, collagen-I) increased because of the ECM-like structure. Based on the results, the novel micro/nano-fibrous scaffold might be a promising candidate for bone tissue engi- neering.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0300500)the Youth Innovation Promotion Association CAS(No.2021294)+1 种基金the National Natural Science Foundation of China(No.51571047)Ningbo Major Special Projects of the Plan"Science and Technology Innovation 2025"(No.2018B10084)。
文摘Structure,magnetic properties and ductile of melt-spun Fe_(83-x)Si_(4)B_(13-y)C_(y)Cu_(x)(x=0-1.7;y=0-8)alloys were investigated.The addition of 1.7 at.%Cu in a Fe_(83)Si_(4)B_(13) amorphous alloy generates abundantα-Fe crystals by providing nucleation sites,and further C doping promotes the growth of the crystals by suitable turning amorphous-forming ability,hence they increase saturation magnetic flux density(B_(s))and slightly worse magnetic softness of the as-spun alloys.The as-spun Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy possesses a combined structure of a fully amorphous layer in wheel side surface and predominating nanocrystalline structure with gradually enlargedα-Fe crystal,whose average size and volume fraction are determined as about 12 nm and 32%,respectively,therefore superior soft magnetic properties and ductile with a high B_(s)of 1.74 T,coercivity(H_(c))of 32.7 A/m,effective permeability(μ_(e),at 1 kHz)of 3200 and high relatively strain at fracture(ε_(f))of 3.61%can be achieved directly in this alloy by only using melt-spinning.The annealing at 578 K releases internal stress,promotes the growth of theα-Fe crystals and remains the amorphous layer of the Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy,then improves the soft magnetic properties and maintains the superior ductile with increasing the B_(s)andμ_(e)to 1.80 T and 14,100,respectively,lowering the H_(c)to9.4 A/m and slightly reducing theε_(f)to 2.39%.The combination of superior soft magnetic properties and ductile and simplified synthesis process entitles the Fe-Si-B-C-Cu nanocrystalline alloys great potentials in high performance electromagnetic applications.
基金support from the National 863 Program(No.2006AA03A217)
文摘A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis(methylamino)borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine(PBN).This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine(TCB) with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.
基金ProjectsupportedbyaGrant in AidfortheCreationofinnovationsthroughBusiness Academic PublicSectorCooperation
文摘The reduction diffusion method was performed for the sludge scrap of Nd-Fe-B sintered magnets with adding Ca metal to recover the oxidized Nd-Fe-B phase. After washing the resultant powders to remove Ca metal component, the powders obtained were recycled as an isotropic magnetic powder by the melt spinning method. The magnetic properties of powders as recycled were inferior, especially for the coercivity value, due to the deletion of rare earth metals during the washing process. The adjustment of metal composition, i.e., the addition of Nd metal, at the melt spinning process improved the magnetic properties to be B r=~0.75 T, H cj=~0.93 mA·m -1, and (BH) max=~91 kJ·m -3. The magnetic properties of the bonded magnets prepared from the composition-adjusted powders were B r=~0.66 T, H cj=~0.92 mA·m -1, and (BH) max=~70 kJ·m -3, which are approximately comparable to the commercially available MQPB boned one (B r=~0.73 T, H cj=~0.79 mA·m -1, and (BH) max=~86 kJ·m -3).
基金This work was supported by“863”Program under grant No.2001AA327022.
文摘A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermo-elastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.
基金Project supported by the National Natural Science Foundation of China(Grant No.51590880)National Key Research and Development Program of China(Grant Nos.2014CB643700 and 2016YFB070090)
文摘The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets. This review first broadly discusses the principle of cooling control, amorphization, crystallization, annealing, and consolidation of the melt-spun ribbons. The phase, microstructure,and magnetic properties of popular single-phase nanocrystalline magnets are reviewed, followed by the nanocomposite magnets consisting of magnetically hard and soft phases. The precipitation-hardened magnetic materials prepared by melt spinning are also discussed. Finally, the role of intergrain exchange coupling, thermal fluctuation, and reversible/irreversible magnetization processes are discussed and correlated to the magnetic phenomena in both single-phase and nanocomposite magnets.
基金Project(2007AA03Z227)supported by High-tech Research and Development Program of ChinaProjects(50871050,50701011)supported by the National Natural Science Foundation of China+1 种基金Project(200711020703)supported by the Natural Science Foundation of Inner Mongolia,ChinaProject(NJzy08071)supported by High Education Science Research Project of Inner Mongolia,China
文摘The La-Mg-Ni system A2B7-type electrode alloys with nominal composition La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1(x=0,0.05, 0.1,0.15,0.2)were prepared by casting and melt-spinning.The influences of melt spinning on the electrochemical performances as well as the structures of the alloys were investigated.The results obtained by XRD,SEM and TEM show that the as-cast and spun alloys have a multiphase structure,consisting of two main phases(La,Mg)Ni3 and LaNi5 as well as a residual phase LaNi2.The melt spinning leads to an obvious increase of the LaNi5 phase and a decrease of the(La,Mg)Ni3 phase in the alloys.The results of the electrochemical measurement indicate that the discharge capacity of the alloys(x≤0.1)first increases and then decreases with the increase of spinning rate,whereas for x>0.1,the discharge capacity of the alloys monotonously falls.The melt spinning slightly impairs the activation capability of the alloys,but it significantly enhances the cycle stability of the alloys.
基金supported by the China Postdoctoral Science Foundation(CPSF)(No.2007CB613900)the National Basic Research Priorities Program of China(No.2007CB613905)+1 种基金the Program for New Century Excellent Talents in the University,the Ministry of Education of China(No.50671050)the National Natural Science Foundation of China(Nos.50671050 and 50971073).
文摘Fe-based amorphous alloys with high iron content of 76at%-80at%were synthesized in the Fe-Mo-Si-P-C-B alloy system by the single roller melt-spinning technique.The amorphous ribbons exhibit high Vickers microhardness and good ductility,which can be indented and bent 180°without breaking.A number of shear bands could be observed around the indents and the bending traces.Studies on the magnetic properties of the amorphous alloys show that they possess high saturation magnetizations of 1.34-1.6 T,which increases with the increase of iron content.The core losses of these Fe-based amorphous alloys at various magnetic inductions were tested and found to be significantly dependent on their components.The Fe-Mo-Si-P-C-B amorphous alloys with excellent mechanical properties and soft magnetic properties have promising potential in functional applications.
文摘Nd8.5Fe74Co5Cu1Nb1Zr3Cr1B6.5 bonded magnets were prepared by melt-spun and subsequent heat treatment. Magnetic properties of Br=0.68 T,JHc=716 kA/m, (BH)max=77 kJ/m3 were achieved. The addition of Cr element shows to be significantly advantageous in reducing grain size and increasing the intrinsic coercivity.
文摘Sn/Sb based alloy anodes have attracted considerable interest as electrodes for next-generation high performance Li-ion batteries (LIBs) owing to their high theoretical capacities. And fabricate porous structure is an effective way to improve materials’ cycling performance. Here, we developed nanoporous SnSb alloy ribbon (NP-SnSb) through a melt-spinning/chemical-etching process and took it as electrode of LIB directly. Being of self-supported and binder free, the NP-SnSb shows a total outperformance over its nonporous counterparts both in cycling performance and kinetic characteristic. Besides, considering the melt-spinning/chemical-etching synthetic process is high-through-put and simple, the ribbon kind of alloy anodes have strong potential application for LIBs research.
文摘The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used to prepare the La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) electrode alloys. The impacts of the melt spinning and the substituting La with Zr on the structures and the electrochemical hydrogen storage characteristics of the alloys were systemically investigated. The analysis of XRD and TEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning ameliorate the electrochemical cycle stability of the alloys dramatically. Furthermore, the high rate discharge ability (HRD) of the as-spun (10 m/s) alloys notably declines with growing the amount of Zr substitution, while it first augments and then falls for the (x=0.1) alloy with rising the spinning rate.
文摘The present study reported the influence of heavy rare-earth elements(Gd and/or Dy)on Sm-Co-based melt-spun ribbons.Microstructure and magnetic properties of Sm-Co-based(Sm_(1-x)RE_(x)Co_(5))ternary and quaternary systems were investigated.The X-ray diffraction,Auger spectroscopy,scanning electron microscopy(SEM)and transmission electron microscopy(TEM)analyses reveal the presence of the 1:5H and 2:17R phases in the as-spun ribbons.A high-temperature magnetic measurement reports a Curie temperature(Tc)at~825 and~869 K in Sm0.6Gd0.4Co5(ribbon A)and Sm_(0.6)Gd_(0.3)Dy_(0.1)Co_(5)(ribbon B),respectively.A low-temperature magnetic measurement on Sm0.6Gd0.3Dy0.1Co5 ribbons exhibits a type-2 SR(spin reorientation)behaviour at~72 K,which arises due to the presence of the DyCo5 phase.Room temperature magnetic measurements reveal that overall magnetic measurement(OMP)is about 24 and 29.9 for ribbons A and B,respectively.Consequently,the comparative investigations profess that ribbon B shows better magnetic performance due to Dy addition with reduced grain size.This observation indicates that the Gd and Dy substituted Sm-Co magnet can be a potential magnet for high-temperature applications.
文摘A new Al-based amorphous alloy with excellent corrosion resistance and high thermal stability was produced in the Al-Co-RE(Ce-La)system.In this regard,two different amorphous-nanocrystalline ribbons:Al_(87.6)-Co_(6.4)-Ce_(3.8-)La_(2.2)(M_(1))and Al_(82.3)-Co_(10.1)-Ce_(4.8)-La_(2.8)(M_(2))were prepared using melt spinning.The results reveal the supercooled liquid region(ATx)of 218℃which shows that the M2alloy has higher thermal stability in comparison to the M1alloy.The M2ribbons present the superior corrosion resistance because of the formation of amorphous phase.The icorr,Ecorr,Epit,and Epit-Ecorrvalues of fully amorphous Al-Co-Ce-La metallic ribbons have a better trend of anti-corrosion performance compared to other crystalline and amorphous aluminum alloys.
基金financially supported by the National Natural Science Foundation of China (No. 51774146)the Guangzhou Municipal Science and Technology Program (No. 201605120111410)
文摘To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Cei7Fe78-xTaxB6 (x = 0-1) alloys, the coercivity Hc increases from 439 to 553 kA/m with increasing x value from 0 to 0.75. Microstructure characterizations indicate that Ta doping is helpful for grain refinement. A second phase of TaB2 is observed in Ce17Fe77.25Tao.75B6 alloy, which acts as the pinning center of the magnetic domains, resulting in the change of coercivity mechanism from nucleation type to nucleation +pinning type. The micromagnetic simulation confirms that non-magnetic particles within hard magnetic phase can increase the demagnetization field around them and it is crucial for preventing the further magnetization reverse by pinning effect. Take the advantage of Ta doping for enhancing the coercivity, Ce content of Ce-Fe-B alloy can be further cut down to increase the remanence Jr due to the reduced volume fraction of CeFe2 phase and increased Fe/Ce ratio. As a result, a good combination of magnetic properties with Hc = 514 kA/m, Jr = 0.49 T, and the maximum energy product (BH)max = 36 kJ/m^3 have been obtained in Ce15Fe79.25Tao.75B6 alloy. It is expected that the present work can serve as a useful reference for designing new permanent magnetic materials with low-cost.
基金Project supported by National Science and Technology Program-International Collaborative Research Project (2010DFA51920)
文摘The novel A1-5Ti-IB-1RE nanoribbons were synthesized by melt-spinning. The microstructure showed that the A1-5Ti- 1B-1RE nanoribbon consisted of granular-like TiB2 and core-shell-like TiA13/Ti2A120Ce. The A1-5Ti-IB-1RE nanoribbon could give rise to the excellent refining effect on as-cast A356 alloys. The refining efficiency and formation mechanism of A1-5Ti-IB-IRE nanoribbons were investigated. In accordance with the experimental results, it could be seen that the A1-5Ti-IB-1RE nanoribbon could maintain the refining effect after 60 min of holding. Additionally, owing to the addition of A1-5Ti-IB-1RE nanoribbon, the mechanical properties of A356 alloys could be enhanced significantly.
基金Project supported by HITEMAG European project (G5RD-CT-2000-002B)DARPA Metamaterials program (ADA458377)
文摘We investigated the structural and magnetic properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. Samples were arc melted then melt spun at 37 m/s up to 55 m/s to obtain ribbon for powdering. Annealing was performed in argon atmosphere for 30- 75 min at 600-870 oC. In as-spun ribbons the hexagonal SmCo7 (TbCu7-type of structure) of crystal structure was determined from x-ray diffraction patterns, while fcc-Co has been identified as a secondary phase. After annealing, the 1:7 phase of the as-spun ribbons transformed into 2:17 and 1:5 phases. X-ray patterns for as-milled powders exhibited very broad peaks making it difficult to identify a precise structure but repre-sented the 1:7 structure after annealing at low temperature (650 oC). TEM analysis showed a homogeneous nanocrystalline microstructure with average grain size of 30-80 nm. Coercivity values of 15-27 kOe were obtained from hysteresis loops traced up to a field of 5 T. The co-ercivity decreased as temperature increases, but it maintained values higher than 5 kOe at 380 oC. The maximum energy product at room temperature increased, as high as 7.2 MGOe, for melt-spun isotropic ribbons produced at higher wheel speeds. Anisotropic ribbons had a maximum energy product close to 12 MGOe.
基金Project supported by the National Basic Research Program of China(973 Program)(2014CB643703)the National Key Research and Development Program of China(2016YFB0700901)+1 种基金the National Natural Science Foundation of China(51761008,51461013)the Guangxi Natural Science Foundation(2016GXNSFDA380015,2016GXNSFGA380001)
文摘The effect of wheel speed on phase formation and magnetic properties of (Ndo.4La0.6)lsFeTzsBzs and (Ndo.4La0.6)13.4Fe79.9B6.7 ribbons prepared by melt-spinning method was investigated experimentally. Based on X-ray diffraction results, all melt-spun ribbons consist of the main phase with the tetragonal 2:14:1 type structure and the minor α-Fe phase. Magnetic measurements show the maximum magnetic energy product ((BH)max) and the remanence (Mr) increases firstly and then decreases with the increase of wheel speed, while the coercivity (Hci) increases, resulting from the variation of the average volume fraction of the ^-Fe phase and the average grain size in the melt-spun ribbons. Using Henkel plots, the interaction between the 2:14:1 phase and the ^-Fe phase in the melt-spun ribbons was analyzed and the intergranular exchange coupling is manifested. Optimal magnetic properties of Hci - 7.27 kOe, Mr - 90.94 emu/g and (BH)max -- 12.10 MGOe are achieved in the (Ndo.4La0.6)lsFeTzsBT.s ribbon with the wheel speed of 26 m/s. It indicates that magnetic properties of Nd-Fe-B melt-spun ribbons with highly abundant rare earth element La can be improved by optimizing alloy composition and preparation process.