A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5...A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1), after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).展开更多
Composite coatings made of nano-Y_2O_3/cobalt-based alloy and produced by crosscurrent CO_2 laser on Ni-based superalloy are introduced. Cross-section or surface of the coatings was examined to reveal their microstruc...Composite coatings made of nano-Y_2O_3/cobalt-based alloy and produced by crosscurrent CO_2 laser on Ni-based superalloy are introduced. Cross-section or surface of the coatings was examined to reveal their microstructure using optical microscope, SEM, including EDS microanalysis, TEM and XRD. The results show that some equilibrium or non-equilibrium phases, such as γ-Co, Cr_(23)C_6, Y_2O_3 and ε-Co exist in the coatings. Fine and short dendritic microstructure and columnar to equiaxed transition (CET) occurred by adding nano-Y_2O_3 particles. With the increasing amount of nano-Y_2O_3 (1%, mass fraction), fully equiaxed crystallization appeared. These are caused by nano-Y_2O_3 particles acting as new nucleation site and rapid solidification of the melt. The results also show that inhomogeneous dispersion of nano-Y_2O_3 results in the formation of ε-Co phase in the coatings. The sub-microstructure of the clad is stacking fault. The mechanism of the formation of equiaxed grains is also analyzed.展开更多
The Al-based amorphous and nanocrystalline composite coatings with the composition of Al-Ni-Y-Co and Al-Ni-Mm-Fe were prepared on AZ91 Mg-based alloys by high velocity arc spraying technique(HVAS).The structure charac...The Al-based amorphous and nanocrystalline composite coatings with the composition of Al-Ni-Y-Co and Al-Ni-Mm-Fe were prepared on AZ91 Mg-based alloys by high velocity arc spraying technique(HVAS).The structure character of the coatings indicates that coatings contain the mixture of amorphous phases and crystalline and there are both less than 2%porosity.The electrochemical tests of the coatings and the substrate were studied.The coatings show the passivation ability during polarization,but AZ91 Mg-based alloys show little passivation.The corrosion current density of the coatings is lower than that of AZ91 Mg-based alloys.The results show that the coatings have an excellent corrosion resistance for AZ91 Mg-based alloys in 5 wt%NaCl solution.展开更多
Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique...Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique.Their structural,static magnetic properties and high-frequency magnetic characteristics were investigated.In the energetic cluster deposition method,by applying a high-bias voltage to a substrate,positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source,to form a high-density Fe-Co alloy cluster-assembled film with good high-frequency magnetic characteristics.In the conventional magnetron sputtering method,only by rotating substrate holder and without applying a static inducing magnetic field on the substrates,we produced Fe-Co-based nanocrystalline alloy films with a remarkable in-plane uniaxial magnetic anisotropy and a good soft magnetic property.The obtained Fe-Co-O,Fe-Co-Ti-N,and Fe-Co-Cr-N films all revealed a high real permeability exceeding 500 at a frequency up to 1.2 GHz.This makes Fe-Co-based nanocrystalline alloy films potential candidates as soft magnetic thin film materials for the high-frequency applications.展开更多
The thermal stability of milling Fe86Zr11-xNbxB3(x=5.5, 6) melt-spun strip powders and the influence of high-pressure sintering conditions on phase component and grain size of bulk alloys were investigated by X-ray ...The thermal stability of milling Fe86Zr11-xNbxB3(x=5.5, 6) melt-spun strip powders and the influence of high-pressure sintering conditions on phase component and grain size of bulk alloys were investigated by X-ray diffractometry(XRD), differential scanning calorimetry(DSC) and scanning electron microscopy(SEM). The results show that milling melt-spun powder remains in the amorphous state, and the crystallization temperature of which is 480530℃, the apparent activation energy Ep of crystallization process is 294.1219.5kJ/mol. The increasing Nb content can increase crystallization temperature and decrease Ep. Under the sintering conditions of 5.5GPa/3min, when Pw is 1150W, single phase α-Fe nanocrystalline (20.626.7nm) bulk alloy with relative density higher than 99.0% can be obtained. Under the sintering conditions of 5.5GPa/1150W/3min, the magnetic properties of these nanocrystalline bulk alloys are Fe86Zr5.5Nb5.5B3 alloy, Bs=1.15T, Hc=5.08kA·m-1; Fe86Zr5Nb6B3 alloy, Bs=1.26T, Hc=4.27kA·m-1.展开更多
Influence of composition and annealing temperature on structure and magnetic properties of amorphous and nanocrystalline Fe78.4-xCoxSi9B9Nb2.6Cu1 (x=27.4, 40.0, 51.0, 78.4) alloys was investigated by X-ray diffracti...Influence of composition and annealing temperature on structure and magnetic properties of amorphous and nanocrystalline Fe78.4-xCoxSi9B9Nb2.6Cu1 (x=27.4, 40.0, 51.0, 78.4) alloys was investigated by X-ray diffraction (XRD) and the temperature dependence of permeability. According to the initial crystallization temperature (Tx1) from differential scanning calorimetry (DSC) curves of as-quenched amorphous alloys, 490-700 ℃ isothermal annealing was carded out to obtain the characteristic nanocrystalline structure. Furthermore, the soft magnetic properties were measured by temperature evolution of magnetic permeability to obtain the correlation between Co content, annealing temperature and magnetic permeability. The results show that, on the one hand, the annealing temperature exerts a significant effect on phase structure and initial permeability (μi). The higher-temperature (from 550 to 610 ℃) annealed Co content nanocrystalline samples can remain higher μi at elevated temperature. On the other hand, partial substitution Fe by Co can improve the high-temperature magnetic stability;however, the room-temperature permeability of higher Co content alloys decreases obviously at the same time. This phenomenon was analyzed from the viewpoint of the saturation magnetic induction (Bs), magnetic anisotropy (〈K〉) and magnetostriction (λs).展开更多
The amorphous matrix contAlning dispersive high number density (Na) α-Fe nuclei with average grAln sizes (D) of 4.3-6.2 nm was formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx (x = 0-2) alloys, and the Nd and D v...The amorphous matrix contAlning dispersive high number density (Na) α-Fe nuclei with average grAln sizes (D) of 4.3-6.2 nm was formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx (x = 0-2) alloys, and the Nd and D values reduce with increase in the Nb content. The fine nanocrystalline structure with α-Fe grAlns of 14.0-21.6 nm in size was obtAlned for the annealed alloys, which showed high saturation magnetic flux density of 1.60-1.77 T and low coercivity (He) of 7.1-17.0 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtAlning good soft magnetic properties, while coarsens the α-Fe grAlns, leading to a slight increase in the Hc. The mechanism of the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.展开更多
The effect of Cu addition on crystallization behavior and soft magnetic properties of Fe 84xP10C6 Cux (x= 0 1.15) alloys was investigated. Low-cost FePCCu nanocrystalline alloys dispersed with α-Fe phase with an aver...The effect of Cu addition on crystallization behavior and soft magnetic properties of Fe 84xP10C6 Cux (x= 0 1.15) alloys was investigated. Low-cost FePCCu nanocrystalline alloys dispersed with α-Fe phase with an average grain size of 15-35nm were obtained by appropriately annealing the melt-spun ribbons at 683K for 5min. The Fe 83.25P10C6Cu0.75 nanocrystalline alloy exhibits a high B s of 1.65T, low H c of 3.3A/m and high eat 1kHz of21 100, which is superior to the traditional FePC soft magnetic alloys. The core loss is as low as 0.32W/kg at1.0 T and 50Hz, which is 60% that of nonoriented Fe 6.5 mass% Si-steel. It is encouraging to synthesize this Fe-based nanocrystalline alloy with excellent soft-magnetic properties even using commercially industry-grade raw materials, which is promising for the future industrial applications.展开更多
文摘A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1), after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).
基金supported by the National 863 projects by the Department of Science and Technology of China (No. 2002AA331080)the Program of Beijing Significant Science and Technology Project (No.020420050021)
文摘Composite coatings made of nano-Y_2O_3/cobalt-based alloy and produced by crosscurrent CO_2 laser on Ni-based superalloy are introduced. Cross-section or surface of the coatings was examined to reveal their microstructure using optical microscope, SEM, including EDS microanalysis, TEM and XRD. The results show that some equilibrium or non-equilibrium phases, such as γ-Co, Cr_(23)C_6, Y_2O_3 and ε-Co exist in the coatings. Fine and short dendritic microstructure and columnar to equiaxed transition (CET) occurred by adding nano-Y_2O_3 particles. With the increasing amount of nano-Y_2O_3 (1%, mass fraction), fully equiaxed crystallization appeared. These are caused by nano-Y_2O_3 particles acting as new nucleation site and rapid solidification of the melt. The results also show that inhomogeneous dispersion of nano-Y_2O_3 results in the formation of ε-Co phase in the coatings. The sub-microstructure of the clad is stacking fault. The mechanism of the formation of equiaxed grains is also analyzed.
基金National Natural Science Foundation of China(50905185)National"863"project of China(2009AA03Z342)
文摘The Al-based amorphous and nanocrystalline composite coatings with the composition of Al-Ni-Y-Co and Al-Ni-Mm-Fe were prepared on AZ91 Mg-based alloys by high velocity arc spraying technique(HVAS).The structure character of the coatings indicates that coatings contain the mixture of amorphous phases and crystalline and there are both less than 2%porosity.The electrochemical tests of the coatings and the substrate were studied.The coatings show the passivation ability during polarization,but AZ91 Mg-based alloys show little passivation.The corrosion current density of the coatings is lower than that of AZ91 Mg-based alloys.The results show that the coatings have an excellent corrosion resistance for AZ91 Mg-based alloys in 5 wt%NaCl solution.
基金supported by the National Natural Science Foundation of China (Grant Nos.50671087,50971108)the National Outstanding Youth Science Foundation of China (Grant No.50825101)the Intellectual Cluster Project of the Ministry of Education,Culture,Sports,Science,and Technology,Japan,Aichi Prefecture,Nagoya City and Aichi Science and Technology Foundation
文摘Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique.Their structural,static magnetic properties and high-frequency magnetic characteristics were investigated.In the energetic cluster deposition method,by applying a high-bias voltage to a substrate,positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source,to form a high-density Fe-Co alloy cluster-assembled film with good high-frequency magnetic characteristics.In the conventional magnetron sputtering method,only by rotating substrate holder and without applying a static inducing magnetic field on the substrates,we produced Fe-Co-based nanocrystalline alloy films with a remarkable in-plane uniaxial magnetic anisotropy and a good soft magnetic property.The obtained Fe-Co-O,Fe-Co-Ti-N,and Fe-Co-Cr-N films all revealed a high real permeability exceeding 500 at a frequency up to 1.2 GHz.This makes Fe-Co-based nanocrystalline alloy films potential candidates as soft magnetic thin film materials for the high-frequency applications.
基金Project(0452NM086) supported by the Tackling Key Science and Technology Programof Shanghai , China
文摘The thermal stability of milling Fe86Zr11-xNbxB3(x=5.5, 6) melt-spun strip powders and the influence of high-pressure sintering conditions on phase component and grain size of bulk alloys were investigated by X-ray diffractometry(XRD), differential scanning calorimetry(DSC) and scanning electron microscopy(SEM). The results show that milling melt-spun powder remains in the amorphous state, and the crystallization temperature of which is 480530℃, the apparent activation energy Ep of crystallization process is 294.1219.5kJ/mol. The increasing Nb content can increase crystallization temperature and decrease Ep. Under the sintering conditions of 5.5GPa/3min, when Pw is 1150W, single phase α-Fe nanocrystalline (20.626.7nm) bulk alloy with relative density higher than 99.0% can be obtained. Under the sintering conditions of 5.5GPa/1150W/3min, the magnetic properties of these nanocrystalline bulk alloys are Fe86Zr5.5Nb5.5B3 alloy, Bs=1.15T, Hc=5.08kA·m-1; Fe86Zr5Nb6B3 alloy, Bs=1.26T, Hc=4.27kA·m-1.
基金supported by the National Natural Science Foundation of China(Nos.51731002,51761032,51871125)。
文摘为了提高La-Y-Mg-Ni合金的储氢性能,通过对铸态合金进行5~30 h的球磨,制备具有非晶和纳米晶结构的La_(1.7)Y_(0.3)Mg_(16)Ni合金,并研究显微组织对储氢性能的影响及其机理。结果表明,随着球磨时间的延长,合金的结晶度、晶粒尺寸和粒径减小,非晶相增加。纳米晶相和非晶相的双重调节作用导致储氢动力学性能先加快,后减慢。经过15 h球磨的合金具有最好的吸、放氢动力学特性,在373 K下10 min内可以吸收3.10%(质量分数)的氢气,其放氢活化能最低,为71.2 k J/mol。球磨不同时间的合金的热力学性能的变化很小,球磨15 h后合金的放氢焓变最低,为72.9 k J/mol。
基金financially supported by the National Natural Science Foundation of China (No. 11604242)Tianjin Research Program of Application Foundation and Advanced Technology, China (No. 14JCQNJC04000)
文摘Influence of composition and annealing temperature on structure and magnetic properties of amorphous and nanocrystalline Fe78.4-xCoxSi9B9Nb2.6Cu1 (x=27.4, 40.0, 51.0, 78.4) alloys was investigated by X-ray diffraction (XRD) and the temperature dependence of permeability. According to the initial crystallization temperature (Tx1) from differential scanning calorimetry (DSC) curves of as-quenched amorphous alloys, 490-700 ℃ isothermal annealing was carded out to obtain the characteristic nanocrystalline structure. Furthermore, the soft magnetic properties were measured by temperature evolution of magnetic permeability to obtain the correlation between Co content, annealing temperature and magnetic permeability. The results show that, on the one hand, the annealing temperature exerts a significant effect on phase structure and initial permeability (μi). The higher-temperature (from 550 to 610 ℃) annealed Co content nanocrystalline samples can remain higher μi at elevated temperature. On the other hand, partial substitution Fe by Co can improve the high-temperature magnetic stability;however, the room-temperature permeability of higher Co content alloys decreases obviously at the same time. This phenomenon was analyzed from the viewpoint of the saturation magnetic induction (Bs), magnetic anisotropy (〈K〉) and magnetostriction (λs).
基金This research was supported by the National Key Research and Development Program of China (Grant No. 2017YFB0903903) and the National Natural Science Foundation of China (Grant Nos. 51571047, 51771039).
文摘The amorphous matrix contAlning dispersive high number density (Na) α-Fe nuclei with average grAln sizes (D) of 4.3-6.2 nm was formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx (x = 0-2) alloys, and the Nd and D values reduce with increase in the Nb content. The fine nanocrystalline structure with α-Fe grAlns of 14.0-21.6 nm in size was obtAlned for the annealed alloys, which showed high saturation magnetic flux density of 1.60-1.77 T and low coercivity (He) of 7.1-17.0 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtAlning good soft magnetic properties, while coarsens the α-Fe grAlns, leading to a slight increase in the Hc. The mechanism of the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.
基金supported by the National High Technology Research and Development Program of China ("863" Program) (Grant No.2009AA03Z214)the National Science Fund of China for Distinguished Young Scholars (Grant No. 50825103)+1 种基金the National Natural Science Foundation of China (Grant No. 51001112)the "Hundred of Talents Program" (Grant No. KGCX-2-YW-803) by Chinese Academy of Sciences
文摘The effect of Cu addition on crystallization behavior and soft magnetic properties of Fe 84xP10C6 Cux (x= 0 1.15) alloys was investigated. Low-cost FePCCu nanocrystalline alloys dispersed with α-Fe phase with an average grain size of 15-35nm were obtained by appropriately annealing the melt-spun ribbons at 683K for 5min. The Fe 83.25P10C6Cu0.75 nanocrystalline alloy exhibits a high B s of 1.65T, low H c of 3.3A/m and high eat 1kHz of21 100, which is superior to the traditional FePC soft magnetic alloys. The core loss is as low as 0.32W/kg at1.0 T and 50Hz, which is 60% that of nonoriented Fe 6.5 mass% Si-steel. It is encouraging to synthesize this Fe-based nanocrystalline alloy with excellent soft-magnetic properties even using commercially industry-grade raw materials, which is promising for the future industrial applications.