Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to domi...Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous asdeposited film. The hardness increases with increasing deposition tempera ture and may even exceed that of crystalline A1MgB14 mate rial. The high hardness may be attributed to the existence of randomly distributed B 12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.展开更多
The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger elect...The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.展开更多
The results of thermomagnetic (TM) and calorimetric (DSC) measurements have been compared in order to clarify some details of the mechanism of nanophase-formation from Finemet-type precursors with different Nb content...The results of thermomagnetic (TM) and calorimetric (DSC) measurements have been compared in order to clarify some details of the mechanism of nanophase-formation from Finemet-type precursors with different Nb contents. It was found that the main features of the DSC thermograms (shape, relative separation and amplitude of the exothermic peaks characteristic for the precipitation of the Fe-(Si) solid solution and the transition metal borides) depend mainly on the composition of the precursor glass, and are only slightly affected by the heating rate between 20 and 80 K/min. The amplitude of the uprise of the magnetization in the TM curves (attributed to the precipitation of bcc-Fe(Si) and borides) decreases with increasing Nb-content. The Curietemperature of the precursor glasses. Tc(am1), the remainder amorphous phases, Tc(am2) and the bcc nanophase, Tc(n-Fe) are determined from the thermomagnetic curves. The shape of the TM curves is interpreted on the basis of the reactions describing the crystalIization of the hypo-eutectic Fe-B glasses.展开更多
L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is f...L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is found the L1_(0)-FeNi in annealed samples at 400℃mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 600 C lower than the measured onset temperature of the second stage with a50 C/min heating rate.Annealing at 4000 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1_(0)phase,or the removal of B from L1_(0)lattice and improvement of the ordering quality of L1_(0)phase due to the reduced temperature from520℃to 400℃.The first stage of crystallization has hardly direct contribution to L1_(0)-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1_(0)-FeNi has the effect of enhancing the thermal stability of L1_(0)phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1_(0)-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.展开更多
The surface nanocrystallization of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by CO2 laser was studied by means of M（oe）ssbauer spectroscopy, transmission electro iroscope and X-ray diffraction. The result shows that ...The surface nanocrystallization of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by CO2 laser was studied by means of M（oe）ssbauer spectroscopy, transmission electro iroscope and X-ray diffraction. The result shows that under certain technical conditions, nanocrystalline is fiound on the surface of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by laser; the crystallization phase is α-Fe（Si） crystalline, and its size is about 10-20 nm; the nanocrystalline is uniformly distributed on amorphous base to keep the amorphous and crystallized phase in balance; the a mount of crystallization reaches 23% when the laser power is 300 W, the diameter of light spot is 20 mm, and the radiation speed is 20 mm/s. The phase balance can be controlled by adjusting the laser technology parameter. Laser radiation on the amorphous Fe73.5 Cu1Nb3Si13.5B9 alloy is an important technique for surface nanocrystallization of the amorphous alloys.展开更多
We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1-yNiy:H:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in prese...We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1-yNiy:H:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T -1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.展开更多
Amorphous Ti-Cu-Zr-Ni filler foils with low melting point of 1 133 K were synthesized using a melt-spinning method in argon atmosphere. A Ti2A1Nb based alloy was brazed at 1 153-1 223 K for 600-3 000 s. The effects of...Amorphous Ti-Cu-Zr-Ni filler foils with low melting point of 1 133 K were synthesized using a melt-spinning method in argon atmosphere. A Ti2A1Nb based alloy was brazed at 1 153-1 223 K for 600-3 000 s. The effects of brazing temperature （Tb） and time （tb） on the shear strength of the joints were investigated. The results showed that the joint strength was significantly affected by the reaction layer thickness. The optimum brazing parameters can be determined as follows： Tb=l 173 K, and tb=600 s. The maximum tensile strength of the joint obtained can reach 260 MPa. Furthermore, the activation energy Q and the growth velocity A0 of the reaction layer in the brazed joints were calculated to be 161.742 kJ/mol and 0.213 m2/s, respectively. The growth of the reaction layer （y） could be expressed by the expression： ya =0.213exp（-19 454/Tb）tb.展开更多
The crystallographic structure of La1/3NbO3 perovskite was studied at high pressures using a diamond-anvil cell and synchrotron radiation. High-pressure energy dispersive (EDS) x-ray diffraction and high-pressure angl...The crystallographic structure of La1/3NbO3 perovskite was studied at high pressures using a diamond-anvil cell and synchrotron radiation. High-pressure energy dispersive (EDS) x-ray diffraction and high-pressure angle dispersive (ADS) x-ray diffraction revealed an irreversible amorphization at ~10 GPa. A large change in the bulk modulus accompanied the high-pressure amorphization.展开更多
On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si1-yNiy:H exhibits that the electrical co...On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si1-yNiy:H exhibits that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T-1/2. This behaviour showed that long range electron-electron interaction reduces the Density Of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature TC, we obtained the Mott Variable Range Hopping regime with T-1/4, indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature TC decreases with nickel content in the alloys.展开更多
The Curie temperature increases but crystallization temperature decreases with the in- crease of Ga content,x,of amorphous(Fe_(1-x)Ga_x)_(77.5)Nd_4B_(18.5) alloys.The average magnetic moment of Fe atoms is almost a co...The Curie temperature increases but crystallization temperature decreases with the in- crease of Ga content,x,of amorphous(Fe_(1-x)Ga_x)_(77.5)Nd_4B_(18.5) alloys.The average magnetic moment of Fe atoms is almost a constant.By X-ray diffraction and ther- momagnetic measurements,the crystalline phases of the alloys,an unknown phase and α-(Fe,Ga)besides Fe_3 B as major one,were identified.The relationship between room temperature coercive field and Ga.content was also studied.展开更多
The influence of 1H-benzo[f]indole(Bd) and its derivatives on room temperature phosphorescence(RTP)has raised great concern since they were found to significantly affect RTP of the extensively studied carbazole(Cz) de...The influence of 1H-benzo[f]indole(Bd) and its derivatives on room temperature phosphorescence(RTP)has raised great concern since they were found to significantly affect RTP of the extensively studied carbazole(Cz) derivatives. However, the role of Bd itself existing in Cz-based or other doping systems was still unclear. In order to clarify its intrinsic phosphorescent property, Bd was introduced as a vip into different organic matrixes including substituted Cz derivatives and polymers. The phosphorescence located in 560–620 nm was confirmed to be derived from Bd itself, which can be detected whatever Bd was doped in the crystal or amorphous state of Cz derivatives. The suitable energy gap between Cz derivatives and Bd is the key to achieve ultralong RTP of Bd. Additionally, when doped in polymers with plenty of hydrogen bonds, RTP of Bd with lifetime over 280 ms was easily obtained. Among them, Bd@PHEMA(poly(hydroxyethyl methacrylate) exhibited superior phosphorescence, with yellow afterglow lasting for over 2.5 s. Therefore, this work demonstrated that a new organic RTP phosphor, Bd, is discovered, and ultralong RTP of Bd can be achieved not only doped in Cz derivatives but also in polymers as the hosts.展开更多
Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magn...Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.展开更多
The nanocrystalline structure of annealed Fe73.5 Cu1 W3Si13.5B9 alloy has been investigated by using the XRD and the TEM methods. The relation between the initial permeability and the microstructure of the annealed al...The nanocrystalline structure of annealed Fe73.5 Cu1 W3Si13.5B9 alloy has been investigated by using the XRD and the TEM methods. The relation between the initial permeability and the microstructure of the annealed alloy has been discussed. The crystalline phase in annealed Fe73.5 Cu1 W3Si13.5B9 alloy is the α-Fe(Si) phase with DO3 superstructure. The volume fraction, Si content and degree of order of the αFe(Si) phase increase with increasing annealing temperature. In the temperature range of 490-570℃, the α-Fe(Si) phase has a size of 13 nm, and its grain number increases as the annealing temperature is increased. The DO3 ordered region in the α-Fe(Si) grain is spherical approximately, and its size increases as the annealing temperature increases. The size of the DO3 ordered region is 12.8 nm at the temperature of 570℃,which is close to that of the α-Fe(Si) grain. There is obvious change in the structure of the residual amorphous phase during annealing, and the nearest atomic distance and the short-range order of residual amorphous phase reach maximum and minimum at 530℃, respectively. The initial permeability of annealed Fe73.5 Cu1 W3Si13.5 B9 alloy is not only dependent on the size, volume fraction and Si content of the α-Fe(Si) phase but also related to the structure state of the residual amorphous phase.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.DUT10JN08)the Natural Science Foundation of Jiangsu Province(No.BK2011252)the Industry Science and Technology Supported Plan of Changzhou(No.CE20110012)
文摘Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous asdeposited film. The hardness increases with increasing deposition tempera ture and may even exceed that of crystalline A1MgB14 mate rial. The high hardness may be attributed to the existence of randomly distributed B 12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.
文摘The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.
文摘The results of thermomagnetic (TM) and calorimetric (DSC) measurements have been compared in order to clarify some details of the mechanism of nanophase-formation from Finemet-type precursors with different Nb contents. It was found that the main features of the DSC thermograms (shape, relative separation and amplitude of the exothermic peaks characteristic for the precipitation of the Fe-(Si) solid solution and the transition metal borides) depend mainly on the composition of the precursor glass, and are only slightly affected by the heating rate between 20 and 80 K/min. The amplitude of the uprise of the magnetization in the TM curves (attributed to the precipitation of bcc-Fe(Si) and borides) decreases with increasing Nb-content. The Curietemperature of the precursor glasses. Tc(am1), the remainder amorphous phases, Tc(am2) and the bcc nanophase, Tc(n-Fe) are determined from the thermomagnetic curves. The shape of the TM curves is interpreted on the basis of the reactions describing the crystalIization of the hypo-eutectic Fe-B glasses.
基金supported by the National Natural Science Foundation of China(Grant Nos.51971179 and 51971180)the Natural Science Foundation of Chongqing,China(Grant No.cstc2019jcyj-msxmX0328)+3 种基金Shaanxi Provincial Natural Science Foundation,China(Grant No.2020JM-112)Guangdong Provincial Science and Technology Program,China(Grant No.2019B090905009)the Fundamental Research Funds for the Central Universities of China(Grant No.D5000210731)Shaanxi Provincial Key R&D Program,China(Grant No.2021KWZ-13)。
文摘L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is found the L1_(0)-FeNi in annealed samples at 400℃mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 600 C lower than the measured onset temperature of the second stage with a50 C/min heating rate.Annealing at 4000 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1_(0)phase,or the removal of B from L1_(0)lattice and improvement of the ordering quality of L1_(0)phase due to the reduced temperature from520℃to 400℃.The first stage of crystallization has hardly direct contribution to L1_(0)-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1_(0)-FeNi has the effect of enhancing the thermal stability of L1_(0)phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1_(0)-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.
文摘The surface nanocrystallization of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by CO2 laser was studied by means of M（oe）ssbauer spectroscopy, transmission electro iroscope and X-ray diffraction. The result shows that under certain technical conditions, nanocrystalline is fiound on the surface of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by laser; the crystallization phase is α-Fe（Si） crystalline, and its size is about 10-20 nm; the nanocrystalline is uniformly distributed on amorphous base to keep the amorphous and crystallized phase in balance; the a mount of crystallization reaches 23% when the laser power is 300 W, the diameter of light spot is 20 mm, and the radiation speed is 20 mm/s. The phase balance can be controlled by adjusting the laser technology parameter. Laser radiation on the amorphous Fe73.5 Cu1Nb3Si13.5B9 alloy is an important technique for surface nanocrystallization of the amorphous alloys.
文摘We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1-yNiy:H:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T -1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.
基金Funded by the National Natural Science Foundation of China(No.50904021)Scientific Research Starting Foundation of Anhui Polytechnic University(No.2012YQQ006)
文摘Amorphous Ti-Cu-Zr-Ni filler foils with low melting point of 1 133 K were synthesized using a melt-spinning method in argon atmosphere. A Ti2A1Nb based alloy was brazed at 1 153-1 223 K for 600-3 000 s. The effects of brazing temperature （Tb） and time （tb） on the shear strength of the joints were investigated. The results showed that the joint strength was significantly affected by the reaction layer thickness. The optimum brazing parameters can be determined as follows： Tb=l 173 K, and tb=600 s. The maximum tensile strength of the joint obtained can reach 260 MPa. Furthermore, the activation energy Q and the growth velocity A0 of the reaction layer in the brazed joints were calculated to be 161.742 kJ/mol and 0.213 m2/s, respectively. The growth of the reaction layer （y） could be expressed by the expression： ya =0.213exp（-19 454/Tb）tb.
文摘The crystallographic structure of La1/3NbO3 perovskite was studied at high pressures using a diamond-anvil cell and synchrotron radiation. High-pressure energy dispersive (EDS) x-ray diffraction and high-pressure angle dispersive (ADS) x-ray diffraction revealed an irreversible amorphization at ~10 GPa. A large change in the bulk modulus accompanied the high-pressure amorphization.
文摘On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si1-yNiy:H exhibits that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T-1/2. This behaviour showed that long range electron-electron interaction reduces the Density Of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature TC, we obtained the Mott Variable Range Hopping regime with T-1/4, indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature TC decreases with nickel content in the alloys.
文摘The Curie temperature increases but crystallization temperature decreases with the in- crease of Ga content,x,of amorphous(Fe_(1-x)Ga_x)_(77.5)Nd_4B_(18.5) alloys.The average magnetic moment of Fe atoms is almost a constant.By X-ray diffraction and ther- momagnetic measurements,the crystalline phases of the alloys,an unknown phase and α-(Fe,Ga)besides Fe_3 B as major one,were identified.The relationship between room temperature coercive field and Ga.content was also studied.
基金supported by Natural Science Foundation of China (Nos. 51733010, 51873237 and 52073315)Natural Science Foundation of Guangdong (No. 2020A1515010476)+1 种基金Guangdong Natural Science Funds for Distinguished Young Scholar (No. 2017B030306012)Fundamental Research Funds for the Central Universities。
文摘The influence of 1H-benzo[f]indole(Bd) and its derivatives on room temperature phosphorescence(RTP)has raised great concern since they were found to significantly affect RTP of the extensively studied carbazole(Cz) derivatives. However, the role of Bd itself existing in Cz-based or other doping systems was still unclear. In order to clarify its intrinsic phosphorescent property, Bd was introduced as a vip into different organic matrixes including substituted Cz derivatives and polymers. The phosphorescence located in 560–620 nm was confirmed to be derived from Bd itself, which can be detected whatever Bd was doped in the crystal or amorphous state of Cz derivatives. The suitable energy gap between Cz derivatives and Bd is the key to achieve ultralong RTP of Bd. Additionally, when doped in polymers with plenty of hydrogen bonds, RTP of Bd with lifetime over 280 ms was easily obtained. Among them, Bd@PHEMA(poly(hydroxyethyl methacrylate) exhibited superior phosphorescence, with yellow afterglow lasting for over 2.5 s. Therefore, this work demonstrated that a new organic RTP phosphor, Bd, is discovered, and ultralong RTP of Bd can be achieved not only doped in Cz derivatives but also in polymers as the hosts.
基金This work was supported by the National Natural Science Foundation of China(No.59871013).
文摘Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.
文摘The nanocrystalline structure of annealed Fe73.5 Cu1 W3Si13.5B9 alloy has been investigated by using the XRD and the TEM methods. The relation between the initial permeability and the microstructure of the annealed alloy has been discussed. The crystalline phase in annealed Fe73.5 Cu1 W3Si13.5B9 alloy is the α-Fe(Si) phase with DO3 superstructure. The volume fraction, Si content and degree of order of the αFe(Si) phase increase with increasing annealing temperature. In the temperature range of 490-570℃, the α-Fe(Si) phase has a size of 13 nm, and its grain number increases as the annealing temperature is increased. The DO3 ordered region in the α-Fe(Si) grain is spherical approximately, and its size increases as the annealing temperature increases. The size of the DO3 ordered region is 12.8 nm at the temperature of 570℃,which is close to that of the α-Fe(Si) grain. There is obvious change in the structure of the residual amorphous phase during annealing, and the nearest atomic distance and the short-range order of residual amorphous phase reach maximum and minimum at 530℃, respectively. The initial permeability of annealed Fe73.5 Cu1 W3Si13.5 B9 alloy is not only dependent on the size, volume fraction and Si content of the α-Fe(Si) phase but also related to the structure state of the residual amorphous phase.
