Crystallization Behavior and Magnetic Properties of （Fe0.6Co0.4）86Hf7B6Cu1 Alloy

(Fe0.6Co0.4)86HfTB6Cu1 nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630℃) and improve the magnetization of nanocrystalline alloy at high temperature ( ≈ 1.56T at 550℃). After annealing amorphous precursor at 550℃ for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( ≈ 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.     

Crystallization Behavior and Magnetic Properties of (Fe_(o.6)Co_(0.4))_(86)Hf_7B_6Cu_1 Alloy

MORE RECENTLY,it was found that Co substitutionfor Fe in Fe-M-B-Cu(M=Nb,Hf or Zr)alloys canimprove the magnetic properties at high temperature byincreasing the Curie temperature of amorphous phase.Attributed to the exchange coupling ofnanocrystal-amorphous-nanocrystal,the magneticanisotropy can be averaged over many grains andorientations when the grain size is smaller than theexchange coherence length,resulting in a greatlyreduced coercivity.But when the temperature is higherthan the …     

预退火对纳米晶Fe86Zr7B6Cu1合金显微组织和软磁性能的影响

研究在常规退火前的高温短时间预退火对非晶Fe86Zr7B6Cu1合金晶化过程的影响,通过分析温度对形核速率和晶粒长大速率的影响规律,讨论预退火对非晶Fe86Zr7B6Cu1合金晶化过程的影响机制。结果表明,合适的预退火引起纳米晶Fe86Zr7B6Cu1合金中结晶α-Fe相的晶粒尺寸的减小和体积分数的增加。非晶Fe86Zr7B6Cu1合金经600℃退火1 h后的结晶α-Fe相的晶粒尺寸和体积分数分别为13.2 nm和65.2%,而在750℃保温2 min再在600℃退火1 h后的结晶α-Fe相的晶粒尺寸和体积分数分别为9.5 nm和72.4%。在750℃保温2 min再在600℃退火1 h后的试样比常规退火得到的试样具有更为优良的软磁性能。     

Influence of two-step cooling method on magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy

Soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy were studied as a function of cooling condition. The results show that higher permeability and relaxation frequency can be obtained by the two-step cooling method, and the pinning field of the sample obtained by this method is smaller than that of the fitrnace-cooled and water-quenched samples. This phenomenon was interpreted in terms of internal stress and the magnetic ordering of the residual amorphous phase. The two-step cooling treatment is an effective way to improve the soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy.     

Fe- and co-based nanocrystalline soft magnetic alloys modified with Hf, Mo, and Zr: Magnetic properties, thermal stability, and structure. Alloys (Fe0.6Co0.4)86Hf7B6Cu1 and (Fe0.7Co0.3)88Hf7B4Cu1

Nanocrystalline alloys (Fe_0.6Co_0.4)₈₆Hf₇B₆Cu₁ and (Fe_0.7Co_0.3)₈₈Hf₇B₄Cu₁ have been investigated to obtain materials with improved thermal stability and new features. In order to make the alloys produced by melt quenching on a rotating wheel nanocrystalline, they have been subjected to heat (HT) and thermomechanical (TMechT) treatments. The effect of HT and TMechT conditions on the magnetic properties, thermal stability, and structure of the alloys has been studied. The optimal HT conditions for obtaining the minimum values of the coercive force (H _c) in the alloys have been determined. It is shown that TMechT of the alloys leads to the induced longitudinal magnetic anisotropy with the axis of easy magnetization along the long side of the ribbon in the studied temperature range of 520–620°C. It has been established that the alloys (Fe_0.6Co_0.4)₈₆Hf₇B₆Cu₁ and (Fe_0.7Co_0.3)₈₈Hf₇B₄Cu₁ are thermally unstable at temperatures above 500°C.     

退火温度对Fe_(52)Co_(26)Nb_6B_(15)Cu_1合金纳米晶软磁特性及微波磁谱的影响

采用熔体快淬法制备了Fe52Co26Nb6B15Cu1合金非晶薄带,使用非晶晶化法在480、500、550、600、650℃对其进行等温退火处理,后采用机械球磨法将其球磨得到Fe52Co26Nb6B15Cu1合金微细磁粉。结合X射线衍射分析、振动样品磁强计等测试技术研究热处理温度对Fe52Co26Nb6B15Cu1合金纳米晶的微结构及软磁相关性能的影响。在此基础上使用矢量网络分析仪测试并分析了热处理温度对该纳米晶复合材料在500 MHz~18 GHz磁谱的影响。结果表明,通过控制热处理温度可以有效的调控Fe52Co26Nb6B15Cu1合金样品的微结构与软磁性能,进而在较大范围内调整样品的复数磁导率(μ′(2.0~4.2),μ″(1.0~2.5))。     

Influence of low-temperature nitridation on low-frequency magnetization of Fe82Nb7B10Cu1 nanocrystalline alloy ribbons

The nanocrystaUine Fe82Nb7B10Cu1 soft magnetic ribbons were treated with the mixture gas flow of ammonia and hydrogen at 673 K. The influence of the nitridation treatment was studied by the low-frequency permeability spectra. The result shows that this kind ofnitridation treatment can improve the soft magnetic properties under some application conditions. The reason for the improvement of the soft magnetic properties by slight nitridation was discussed on the basis of domain wall bulging model. Therefore for the Fe-based nanocrystalline soft magnetic alloy ribbons, the nitridation treatment can be used as an effective and easy method to control the magnetic properties.     

Fe61Co10Zr5W4B20块体非晶合金的晶化行为与力学性能研究

采用铜模吸铸法制备Ф2mm的Fe61Co10Zr5W4B20块体非晶台金．采用XRD、SEM、DSC、硬度和压缩实验研究了非晶合金的结构组织、热稳定性、晶化特征、硬度和压缩性能。设块体非晶合金表现出二级晶化,其玻璃转变温度为561.1℃．晶化温度为619．0℃．第一晶化峰温度为632.6℃．第二晶化峰比之高约117℃;用Kissinger和Ozawa方法获得的玻璃转变激活能特别为595.1KJ/mol．578.7kJ/mol．晶化激活能分别为413.9kJ／mol,407.4kJ／mol;非晶合金的晶化行为比其玻璃转变表现出更为明显的动力学效应;非晶合金的显做硬度为1207HV．压缩强度为1707．6MPa．呈典型的脆性断裂．断口中光滑区与脉状花纹区并存。     

Fe88Zr7B4Co1软磁纳米晶薄带的巨磁阻抗效应

利用熔旋快淬技术在铜辊速度为40 m/s的条件下制备了Fe88Zr7B4Co1薄带,分别经550、600、650、700、725、750℃退火处理30 min,形成纳米晶薄带.研究了退火温度、外磁场和驱动电流频率对巨磁阻抗效应的影响.发现存在一个最佳退火温度650℃.其bcc α-Fe相的晶粒尺寸为11.3 nm,在此温度下制备的Fe88 Zr7 B4 Co1纳米晶薄带具有最强的巨磁阻抗效应:在H=90 Oe下,频率约为1 MHz时Fe88Zr7B4Co1纳米晶薄带的磁阻抗△Z/Z0达到-52%.Fe88Zr7B4Co1纳米晶薄带具有比未掺杂的Fe88Zr7B4更强的巨磁阻抗效应.     

Structural and magnetic properties of (Sm_0.5Nd_0.5)_2(Fe_(1-x)Co_x)_(17)compounds

The structure, magnetization, and magnetocrystalline anisotropy were investigated using X-ray diffraction, vibrating sample magnetometer, and AC susceptibility-meter. It is found that the microstructure of (Sm0.5Nd0.5)2(Fe1-xCox)17 alloys is an (Sm,Nd)2(Fe,Co)17 phase with the rhombohedral Th2Zn17-type structure. The Curie temperature Tc increases with the Co concentration increasing, and the magnetization first increases as the Co content increases in (Sm0.5Nd0.5)2(Fe1-xCox)17 alloys and then decreases slowly. The easy magnetization direction (EMD) of (Sm0.5Nd0.5)2(Fe0.25Co0.75)17 is along the c-axis and a strong enhancement of the crystalline anisotropy energy constant K is produced by the addition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and then decreases slowly with the Co content further increasing. The (Sm0.5Nd0.5)2(Fe0.25Co0.75)17compound is an optical candidate for the new permanent magnet, which possesses a high magnetization, a high Curie temperature,     

Fe73.5 Cu1 Nb3 Si13.5 B9机械合金化纳米晶粉末的特种烧结及磁性能

研究了放电等离子烧结和高压烧结工艺条件对MA Fe73.5Cu1Nb3Si13.5B9纳米晶粉末的烧结块体合金的组织结构与磁性能的影响.结果表明:球磨70 h后,获得了单相a-Fe纳米晶(约9.5 rm)过饱和固溶体粉末;DSC升温曲线中,出现4个不同强度的放热峰,依次发生了纳米晶过饱和固溶体的结构弛豫、非晶晶化以及过饱和固溶体相析出等过程,且相析出过程分两个阶段完成;在p=30 MPa,t=5 min放电等离子烧结(SPS)条件下,当温度达到1 050℃后,可获得相对密度为98.9%、主相为α-Fe的纳米晶(100nm)块体合金,其中,B3=1.34 T,Hc=7.34 kA/m,在p=5.5 GPa,t=5 min条件下,当Pw=1 150 W后,可获得相对密度约99.1%、单相α-Fe纳米晶(21.4 nm)块体合金,其中,Bs=1.14 T,Hc=8.22 kA/m.     

Crystallization behaviour and high coercivity of （Nd,Pr）（13）Fe（80）Nb1B6 melt-spun ribbons

Amorphous (Nd,Pr)13Fe80Nb1B6 ribbons were crystallized at 670-730℃ for 5-25 min to study the effects of isothermal crystallization on their behavior and magnetic properties. XRD results indicate that the isothermal incubation time is 12, 5, and less than 5 min at 670, 700, and 730℃, respectively. High eoercivities, with the maximum value of iHc = 1616 kA/m at 700℃ for 19 min, measured by a physical measurement system, are obtained in the crystallized ribbons. This is mainly attributed to the addition of Pr and Nb, because Pr2Fe14B has a higher anisotropic field than Nd2Fe14B, and Nb enriched in the grain boundary regions can not only reduce the exchange-coupling effects among hard grains, but also impede grain growth during the crystallization process. In addition, it should also be related to the characteristics of the furnace that the authors designed.     

Magnetic properties,thermal stability,and structure of the nanocrystalline soft magnetic (Fe0.7Co0.3)88Hf2W2Mo2Zr1B4Cu1 alloy with induced magnetic anisotropy

The effect of magnitude of tensile stresses (σ) applied to the (Fe_0.7Co_0.3)₈₈Hf₂W₂Mo₂Zr₁B₄Cu₁ alloy with refractory-metal additions during its nanocrystallization at 620°C for 20 min on the magnetic properties, structure, and thermal stability of the alloy is studied. It has been found that, during the nanocrystallization of the alloy under the effect of tensile stresses of 6–250 MPa, longitudinal magnetic anisotropy with an easy magnetization axis parallel to the long size of ribbon is induced in the alloy. The thermal stability of magnetic properties of the alloy under study has been shown to be determined by the thermal stability of induced magnetic anisotropy and to depend on the magnitude of tensile stresses applied during nanocrystallizing annealing (NA). The better thermal stability of magnetic properties has been observed for the alloy subjected to NA at σ = 170 MPa. After annealing at 570°C for 25 h, the magnetic properties of the alloy are unchanged.     

Magnetic properties and microstructure of nanocrystalline soft magnetic Fe73.5−x Co x Cu1Nb3Si13.5B9 alloys

The influence of the annealing temperature, cooling rate, and magnetic field frequency in thermomagnetic treatment on the magnetic parameters of nanocrystalline Fe_73.5?x Co _x Cu₁Nb₃Si_13.5B₉ (x=0, 10, 20, and 30) alloys has been investigated. It has been revealed that a thermomagnetic treatment in a dc magnetic field of the nanocrystalline alloys containing cobalt leads to a shift of their hysteresis loop. With increasing Co content in the alloy, the shift of the hysteresis loop increases. This fact is, apparently, connected with the precipitation of α-Co and β-Co clusters and (Fe,Co)₃Si and (Fe,Co)₂B nanophases in which the magnetization direction is determined by the direction of the magnetic field during treatment.     

Fe- and co-based nanocrystalline soft magnetic alloys modified with Hf, Mo, and Zr: Magnetic properties, thermal stability, and structure. Alloy (Fe0.7Co0.3)88Hf4Mo2Zr1B4Cu1

The alloy (Fe_0.7Co_0.3)₈₈Hf₄Mo₂Zr₁B₄Cu₁ is studied to obtain materials with improved thermal stability. The effect of the nanocrystallization conditions that occur during heat treatment (HT) and thermomechanical treatment (TMechT) in air at temperatures of 520–620°C on the structure of the alloy, as well as its magnetic properties and their thermal stability, is considered. Longitudinal magnetic anisotropy is shown to be induced in the alloy in the course of TMechT; the easy magnetization axis of the anisotropy is parallel to the long side of the ribbon. The alloy specimens subjected to heat and thermomechanical treatment have different magnetic characteristics. The (Fe_0.7Co_0.3)₈₈Hf₄Mo₂Zr₁B₄Cu₁ alloy is found to surpass the (Fe_0.6Co_0.4)₈₆Hf₇B₆Cu₁ and (Fe_0.7Co_0.3)₈₈Hf₇B₄Cu₁ alloys studied in [1] in the thermal stability of the magnetic properties. The magnetic properties of the alloy after nanocrystallization, which occurs in the course of TMechT (σ = 250 MPa) at 620°C for 20 min, hardly change during annealing at 550°C for 26 h.     

Crystallization kinetics and induced magnetic properties of bulk （Fe,Co）-Zr-Nd-B metallic glass

Crystallization kinetics and phase transformation of bulk Fe64 Co7 Zr6 Nd3B20 metallic glass were studied by X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Based on the Kissinger analyses, the activation energies for the nucleation and growth during the first, second and third crystallization-stages of the metallic glass are determined to be 294, 475 and 365 kJ/mol, respectively, and the activation energy for the glass transition is determined to be 1 242 kJ/mol. The Johnson-Mehl-Avrami (JMA) analysis under the isothermal condition reveals that the crystallization process is a three-dimensional controlled growth of nuclei at a constant nucleation rate. The crystalline grains are in the size of less than 50 nm after the selected annealing treatments. In the completely crystallized state, the alloy exhibits the maximum coercivity (Hc) of 34.8 kA/m and corresponding energy product of 11 kJ/m^3.     

Magnetic properties and crystallization kinetics of Zn_(0.5) Ni_(0.5) Fe_2O_4

Precursor of nanocrystalline Zn0.5Ni0.5Fe2O4 was obtained by grinding mixture of ZnSO4·7H2O,NiSO4·6H2O,FeSO4·7H2O,and Na2CO3·10H2O under the condition of surfactant polyethylene glycol(PEG)-400 being present at room temperature,washing the mixture with water to remove soluble inorganic salts and drying it at 373 K.The spinel Zn0.5Ni0.5Fe2O4 was obtained via calcining precursor above 773 K.The precursor and its calcined products were characterized by differential scanning calorimetry(DSC) ,Fourier transform ...     

High-pressure sintering and magnetic properties of Fe86Zr11-xNbxB3 （x=5.5, 6） amorphous alloys

1 INTRODUCTION Fe-based nanocrystalline soft magnetic alloys become the focus in the world because of their ex- cellent soft magnetic properties and high saturation induction.In engineering applications , soft mag- netic alloys are usually used in bulk form with complex shape . However , nanocrystalline soft magnetic alloys in engineering applications are pre- pared through the crystallization of amorphous al- loy which is controlled by melt spinning, accord- ingly the shape and size of th…     

Structure and magnetic properties ofhigh-performanced Sm2（Co, Fe, Cu, Zr）17 alloys

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