非晶Nd6Fe81B13合金的晶化和磁性

本文研究了非晶Nd_6Fe_(81)B_(13)合金的磁性和晶化及其对样品结构和磁性的影响。讨论了非晶样品的低温磁性和Nd对昌化温度和Curie温度的影响。在873K退火的样品中得到一个新相。     

MAGNETIC PROPERTIES AND CRYSTALLIZATION OF RAPIDLY QUENCHED(Fe_(1-x)Ga_x)_(77.5)Nd_4B_(18.5) ALLOYS

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 averagemagnetic 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 andα-(Fe,Ga)besides Fe_3 B as major one,were identified.The relationship between roomtemperature coercive field and Ga.content was also studied.     

Effect of pulsed laser heating on the magnetic properties of amorphous alloy 30KSR

It has been established using magnetometric methods that irreversible magnetic anisotropy appears in the amorphous ribbon of a 30KSR alloy after pulsed laser heating in an external magnetic field. Effects of laser heatings on the physical properties of the alloy, in particular, on the Curie temperature and the temperature of crystallization have been studied. It has been shown that the direction of the arising magnetic anisotropy does not coincide with the field direction during laser heating. A mechanism of the appearance of the uniaxial magnetic anisotropy of amorphous ribbons during pulsed laser heatings in a magnetic field by regimes which do not lead to crystallization has been suggested.     

MAGNETIC PROPERTIES AND CRYSTALLIZATION OF AMORPHOUS ALLOYS Co_(90-x)Cr_xZr_(10)

Curie temperature of amorphous alloys Co_(90-x)Cr_x Zr_(10) decreases linearly with increas-ing x.Average magnetic moment per magnetic atom Co or Cr is 1.51 μB or -3.62 μBrespectively.The temperature dependence of spontaneous magnetization at low temper-atures is in agreement with Bloch's T~(3/2) law.The spin wave stiffness constant decreaseswith increasing x from 4 to 20.The range of interaction is 2—3 atoms for x=4 andnearest neighbour atom for x=20.The crystallization temperature increases mono-tonically with increasing x.It may relate to the average number of outer electrons peratom.The crystalline phase components of heat-treated alloys were analyzed by X-raydiffration and thermomagnetic measurement.     

Crystallization process and soft magnetic properties of nanocrystalline (Fe0.5 Co0.5 ) 86 Hf7 B6 Cu1 alloy used in elevated temperature applications

Nanocrystalline (Fe0.5 Co0.5 )86 Hf7 B6 Cu1 HITPERM alloy was investigated as the candidate of soft magnetic material for high temperature applications, compared with Fe86 Hf7B6 Cu1 NANOPERM alloy. Amorphous alloy ribbons were prepared by single-roller melt-spinning technology. Crystallization process of as-quenched ribbon was investigated using differential scanning calorimeter at different heating rates. The coercivity was determined from quasi-static hysteresis loop measured at room temperature using a computerized hysteresis loop tracer. X-ray diffraction with Cu Kα radiation was used to determine the structure. The vibrating sample magnetometer was usedto measure the magnetization as a function of temperature of the nanocrystllized alloys. That Co substitution for Fein alloy enhances the Curie temperature of amorphous alloy and the magnetization of nanocrystalline alloy at hightemperature. After annealing amorphous precursor, the optimum nanocrystalline alloy obtained shows the local minimum coercivity. The coercivity increases with the increasing annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization.     

Ferro-paramagnetic transition in a Fe-Ni-Si-B alloy in amorphous and crystalline states

The effect of annealing of an initially amorphous Fe-Ni-Si-B alloy (2HCP) on its Curie temperature for the amorphous and crystalline states has been studied. Annealing at temperatures that correspond to the region of existence of the amorphous phase was found to lead to an increase in the Curie temperature as the annealing temperature increases up to the temperature of the onset of crystallization. The dependence of variations in the Curie temperature on the annealing temperature is described by an exponential function that indicates the development of temperature-activated processes directly in the amorphous phase. In the case of annealing at temperatures above the crystallization temperature, the Curie temperature of the crystalline phase increases with increasing annealing temperature.     

预退火对Fe73.5Cu1Mo3Si13.5B9非晶合金的晶化及磁性的影响

本文研究了预退火温度和时间对Ｆｅ(７３．５)Ｃｕ１Ｍｏ３Ｓｉ(１３．５)Ｂ９非晶合金在最后退火过程中发生的 晶化及软磁性能的影响。结果表明：在较低温度下预退火能有效地控制合金的晶化过程,降低了最 后退火时所放出的晶化潜热。该合金在４５０℃进行１ｈ预退火发生部分晶化,释放约３２％的晶化 潜热,再经５１０℃保温１ｈ最后退火其磁性能与制备态样品经５１０℃退火后的磁性能相比,最大磁 导率ｍ显著提高,矫顽力Ｈｃ明显下降,Ｂｓ和Ｂｒ无明显变化。     

非晶态Fe_(90-x)V_xZr_(10)合金吸氢现象及磁性变化的研究

利用Mossbauer谱、磁测量技术,X射线衍射以及二次离子质谱分析(SIMS)技术,对三元非晶合金Fe_(90-x)V_xZr_(10)吸氢现象及磁性变化进行了研究.实验结果表明:随充氢时间(相同的充氢电流密度)的增加,非晶态合金同质异能移位增加,表明充氢后Fe核处电子密度发生变化.随充氢量增加,室温下合金由顺磁状态转变为铁磁状态,超精细分布逐渐展宽,其最大值也向高场方向移动.吸氢后合金原子磁矩及Curie温度T_C有大幅度增加.0K时饱和磁化强度从未充氢合金的120emu/g增加到174emu/g.Curie温度T_C从257K增加到384K.吸氢导致磁性变化的机理,利用杂化理论模型能够给出很好的解释.     

Effect of pulsed laser heating on the magnetic properties of the amorphous alloy Fe76Si13B11

The appearance of magnetic anisotropy has been established by magnetometric methods in the amorphous Fe₇₆Si₁₃B₁₁ ribbon after pulsed laser heating in an external magnetic field. Effects of laser heating on the physical properties of the alloy, in particular, on the Curie temperature and the temperature of crystallization, have been investigated. It is shown that the value of the remanence of the alloy samples after such treatments in a longitudinal magnetic field increases by a factor of more than three. There is suggested a mechanism of the appearance of a uniaxial magnetic anisotropy of amorphous ribbons during the pulsed laser heating in a magnetic field under conditions that do not lead to the crystallization of the alloy.     

EFFECT OF HYDROGEN ABSORPTION ON MAGNETIC PROPERTIES OF AMORPHOUS Fe_(90-x) V_x Zr_(10) ALLOYS

The amorphous Fe_(90-x)V_xZr_(10) alloy after electolytic hydrogenation procedure was studied bymeans of Mossbauer effect,magnetic measurement.X-ray diffaction and secondary ionmass spectroscopy(SIMS)techniques.The experimental results show that the magneticproperties of amorphous Fe_(90-x)V_xZr_(10) alloy are highly sensitive to the presence of hydrogen.The isomer shift(IS)has a small positive change and the magnetic properties transfer fromparamagnetic to ferromagnetic State by hydrogenation,and the effect of hydrogen absorptionis to raise Fe magnetic moment(from the increase of saturation maguetization)and Curietemperature T_c from 257 to 384 K.Finally.the considerable increase of magnetic properttesof amorphous Fe_(90-x)V_xZr_(10) alloy by hydrogenation is attributable to the change ofhybridization effect between outer electrons of Zr atoms and 3d electrons of Fe atoms.Fromthe results of SIMS experiment,it is concluded that the hydrogen atoms is localized aroundZr atoms wheh hydrogen atoms enter into the allor.     

Effect of Nd substitution on the soft magnetic properties of a nanocrystalline Fe84Nb7B9 Alloy

The substitution effect of Nd for Nb on the structure and magnetic properties of a Fe₈₄Nb₇B₉ alloy has been investigated. The substitution of Nd causes the formation of Fe₃B phase in the as-quenched state; Decrease the crystallization temperature and increase the Curie temperature of the amorphous phase. After annealing at an optimum temperature; The soft magnetic properties are improved by substitution of 0.05 to 0.4 at% Nd and Fe₈₄Nb_6.9Nd_0.1B₉ alloy exhibits the permeability (μ′) at 1kHz of 39000 and the coercivity (H_c) of 4.3 A/m.     

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.     

On the effect of annealing temperature on Curie point in amorphous alloys

The change in the Curie point of the amorphous alloys of the Fe-Ni-Si-As system is investigated after annealing at temperatures below the crystallization temperature. It is shown that, the higher the crystallization temperature of the alloy, the greater the increase in the Curie point during annealing.     

纳米晶(FeCo)78Nb6B15Cu1合金晶化过程及其磁特性研究

采用熔体快淬法制备(FeCo)78Nb6B15Cu1非晶薄带,通过DSC测试薄带的晶化特性,并据此在400,500,700和750℃进行1h退火处理。用XRD和SEM分析薄带在不同退火温度下的晶化行为,并用VSM测试薄带与粉体的静态磁参数。结果表明:对于固定成分的Hitperm合金,选择合适的退火温度,可控制晶粒大小和晶相比例。由于晶粒表面无序磁矩含量的变化,导致材料比饱和磁化强度发生变化,同时更小的纳米晶粒对降低矫顽力有利。由于淬态引入的微量结晶,薄带存在表面晶化现象,这在一定程度上会恶化材料的静态磁特性。     

EFFECT OF ROTATIONAL FIELD ANNEALING ON MAGNETIC ANISOTROPY OF Fe_5Co_(73)Si_(10)B_(12) AMORPHOUS ALLOY

根据非晶态Fe_5Co_(73)Si_(10)B_(12)合金薄带不同方向磁化曲线与磁致伸缩曲线随退火状态的变化规律,发现Curie温度低于晶化温度的非晶态合金经旋转磁场热处理时,可以消除由于自发磁化场所感生的磁各向异性。初步分析和讨论了淬火态(制备)非晶态合金具有磁各向异性的原因。     

MAGNETIC MOMENT,CURIE TEMPERATURE AND SPIN WAVE EXCITATION FOR AMORPHOUS Fe_(90-x)Si_xZr_(10) ALLOYS

The magnetization curves at 1.5 K and thermomagnetic curves for amorphous Fe_(90-x)Si_xZr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique have been measured with an extracting sample magnetometer.It is obtained that the average magnetic moment,,per magnetic atom and Curie temperature,T_c,in the amorphous FeSiZr alloys increase with increasing Si content.The and T_c are found to be quite small,compared with amorphous FeSiB alloys.This unusual behavior is suggested to be due to the presence of the Fe—Fe antiferromagnetic interactions.The temperature dependence of magnetization at lower temperature is in accordance with Bloch's T~(3/2) law.Calculation shows that the spin wave stiffness constant,D,increases with increasing Si content from 0.37 meV·nm~2 for x=0 to 0.538 meV·nm~2 for x=10.The values ofindicate that the range of the exchange interaction is roughly the mean atomic distance of nearest neighbours.     

Boron content dependence of crystallization, glass forming ability and magnetic properties in amorphous Fe-Zr-B-Nb alloys

The glass forming ability (GFA) was investigated in Fe_91−xZr₅B_xNb₄ alloys with B contents of 0–36 at.%. The GFA changes with B content, and fully amorphous alloys were prepared by melt spinning for B contents between 5 and 30 at.%. The amorphous alloys crystallize with a primary crystallization mode in the low B content range of 5≤x≤20 at.%, but in the eutectic mode in the high B content range of 20<x<30 at.%. A single new metastable Fe-Zr-B-Nb cubic phase with a lattice constant of 1.0704 nm, a saturation magnetization of 137 emu/g and a coercivity of 7.3 Oe at room temperature is formed when crystallizing in a polymorphous mode at x=30 at.%. The glass transition temperature (T_g), crystallization temperature (T_x), Curie temperature (T_c) and saturation magnetizations (M_s) of the amorphous alloys increase with increasing B content, but the coercivity (H_c) decreases. As the B content exceeds 20 at.%, not only increase the T_g, T_x and GFA sharply, due to the change of crystallization mode, but also the concentration dependence of the T_c and M_s changes. It is concluded that the amorphous alloys have better GFA, thermal stability and soft magnetic properties for the high B contents of 25–30 at.% than for the low B contents of 5–20 at.%.     

循环处理对Fe基非晶合金微观结构、晶化及磁性能的影响

采用XRD、DSC、TEM等检测方法,研究了深冷循环处理、473K退火循环处理及冷-热循环处理对Fe_(68)Ni_1Al_5Ga_2P9 (6.5)B_(46)Si_3C_(6.75)非晶合金的微观结构、晶化过程及磁性能的影响.结果表明:经不同的循环处理后,试样仍然保持非晶结构,发生了结构弛豫,微观结构改变.但与淬态试样相比,玻璃转变温度、晶化温度及晶化峰值温度存在一定的变化.退火品化后,各试样中析出相的种类、数量、晶粒尺寸等有明显的不同.磁性能数据表明:品化后,循环处理的试样其磁性能较淬态有所提高.     

非晶态Fe_(1-x)(Si,B)_x合金的内禀磁性和磁各向异性

非晶态Fe_(1-x)(Si,B)_x合金的磁矩和磁致伸缩随着Si和B含量的增多而缓慢降低,而Curie温度约在25%(Si+B)含量时呈现出最大值;Si与B的含量对磁各向异性并无明显影响,但表面条纹退磁效应对磁各向异性却有较大的影响。这些实验现象可以借助电子转移和非晶态合金的结构模型得到定性的解释。     

Gd60Co26Al14大块非晶合金的磁熵变

利用铜模吸铸法制备了Gd60Co26Al14非晶合金.采用示差扫描量热法(DSC),X射线衍射(XRD)和超导量子磁强计(SQUID)研究了其结构与磁热性能.XRD分析表明:铸态Gd60Co26Al14合金是完全的非晶结构;DSC测试显示Gd60Co26Al14合金在加热过程中在571 K发生玻璃化转变,并且出现了两个结晶温度,分别是602 K和642 K.SQUID测试结果表明:Gd60Co26Al14合金出现两个居里温度,分别是82 K和128 K;合金在外磁场5 T下82 K处的磁熵变达到7 J·(kg·K-1).