Irradiation effects in amorphous alloy Fe80B20

The Mössbauer effect has been used to study the irradiation effects in the amorphous alloy Fe₈₀B₂₀ after 40 keV helium ion bombardment. Conversion electron Mössbauer spectroscopy reveals the eminent irradiation effects; α-iron phase appears in the damaged region of the sample.     

Fe80B20,Fe80Si6B14金属玻璃中近邻原子间的相互作用

用转靶X射线源及弯晶EXAFS谱仪测定了Fe₈₀B₂₀及Fe₈₀Si₆B₁₄金属玻璃中铁的X射线K吸收谱。由EXAFS谱确定了两种金属玻璃的近邻结构参量。此外,通过测定XANES谱并与纯铁及其有关的化合物Fe₂B,FeB中铁的XANES比较发现:吸收边能量、“白线”结构等均出现一些变化,表明两种金属玻璃的近邻原子Fe-B,Fe-Si以及Fe-Fe之间的相互作用比铁与硼所形成的稳定化合物中要强,这对于决定金属玻璃的短程序结构具有重要的作用。 关键词：     

Temperature dependence of magnetostriction in Fe80B20 glass

The temperature dependence of the magnetostriction of Fe₈₀B₂₀ glass from 12–660 K is reported. It is well described within the theory of Callen and Callen by single-ion terms of uniaxial symmetry. The results suggest that a single-ion mechanism dominates even in crystalline iron-rich alloys.     

Electrical resistivity of amorphous metallic glasses Fe80B80 and Fe78Mo2B20 between 78 and 1000 K

Electrical resistivity (ρ) of amorphous Fe₈₀B₂₀ and Fe₇₈Mo₂B₂₀ have been studied as a function of temperature (T) between 78 and 1000 K. The ρ vs T curves, obtained with specified warming and cooling rates, show that such curves are sensitive probes of the crystallization process. Within the experimental error, no anomalies in the ρ behavior can be seen at the Curie temperature of each amorphous alloy.     

Structure-related effects in the electronic properties of Fe80B20 alloys

The electronic properties of the amorphous and sintered Fe₈₀B₂₀ alloys have been studied by electron energy loss spectroscopy. A correlation among energy loss data and X-ray absorption near edge structures has been attempted.Structure-related effects in the electronic properties of Fe₈₀B₂₀ alloy have been found and discussed.     

Mössbauer effect study of magnetization reorientation in Fe80B20 glass

ME on ⁵⁷Fe nuclei in external-stress-free samples of METGLAS 2605 at various magnetic fields was studied. In external magnetic fields an unusual spin reorientation was observe both in as-quenched and previously annealed/below/T_cryst/materials. The influence of external stress on reorientation of magnetization was tasted.     

Galvanomagnetic effects in Fe40Ni40B20

Hall effect and magnetoresistance measurements on the amorphous ferromagnet Fe₄₀Ni₄₀B₂₀ are reported. Both properties are approximately independent of temperature (1.5–300 K) and related to magnetization. The extraordinary Hall coefficient is 3.5 × 10^?8 m³/As. The temperature dependence of the resistivity (1.5–30 K) is also reported.     

Stoner excitations in the strong itinerant amorphous ferromagnets FexNi80−xB18Si2 and Fe80B20

Accurate measurements of the static magnetization of the amorphous ferromagnets Fe_xNi_80?xB₁₈Si₂ (x = 15, 20, 40, 60%) and Fe₈₀B₂₀ are reported. The results are analyzed in terms of spin-wave and Stoner excitations, and the latter indicate strong itinerant ferromagnetism with a Stoner gap Δ varying between 20 and 60 K. The other fitting parameters give values of the spin-wave stiffness and a quantity simply related to the saturation magnetization. The well-known anomaly regarding the spin-wave stiffness observed in earlier measurements in thus explained quantitatively.     

Pressure dependence of the Curie temperature of amorphous Fe80-xMnxB20 alloys

The pressure effect on the Curie temperature of Fe_{80 - x}Mn_xB₂₀ (x = 6, 10 and 20) amorphous alloys has been investigated. The pressure derivative of the Curie temperature is very large. The model of itinerant electron ferromagnets and the pair interaction model were proposed to explain the experimental results.     

Magnetic properties of amorphous ferromagnet Fe78Mo2B20

Low-field magnetic susceptibility and the magnetic field dependence of magnetization of Metglas 2605 A (Fe₇₈Mo₂B₂₀) were studied between 300 and 600 K and in fields up to 10kG. It is shown here that for an amorphous ferromagnetic alloy, the various methods of determination of Curie temperature T_c give the same value, which in this case is (564 ± 1) K. The critical exponent γ is 1.7 ± 0.1. Our low-field susceptibility measurements on Metglas 2605 (Fe₈₀B₂₀) gives a T_c of (634 ± 3) K while the reported high-field method value is 647 K. These results are discussed in terms of crystallization temperatures.     

Hyperfine field distribution in amorphous Fe40Ni40B20

From the Mössbauer investigation of amorphous Fe₄₀Ni₄₀B₂₀ and Fe₈₀B₂₀ alloys it was found that the substitution of Fe by Ni only shifts but does not influence the shape of the iron hyperfine field distribution contrary to that of crystalline f.c.c. Ni-Fe alloys suggesting a rather localized type of behaviour. The distributions of the linear combinations of isomer shift and quadrupole splitting are affected by this substitution.     

非晶Fe80B20-xMx合金的电子结构的穆斯堡尔谱学研究

从4.2K和室温下非晶Fe₈₀B_20-xM_x合金(M=P,C,Si,Ge)中超精细场和同质异能移的变化关系考察了合金的电子结构.按“刚带-施主”模型估计了从类金属原子向Fe的3d带迁移的电子数;进一步的分析表明,Fe的4s电子在这一电子迁移过程中的影响不可忽略.对于Fe原子磁矩的变化同反方向的电子迁移之间的矛盾,它给出了一个可能的解释. 关键词：     

A Mössbauer study of amorphous Fe40Ni40B20

Amorphous Fe₄₀Ni₄₀B₂₀ (VITROVAC 0040) alloy has been investigated using ⁵⁷Fe Mössbauer Spectroscopy. The Curie temperature T_c is found to be well defined and is 695 ± 1 K. The quadrupole splitting just above T_c is 0.64 mm sec^?1. The crystallization temperature is 698 ± 2 K, close to but definitely above T_c. The average hyperfine field H_eff(T) of the glassy state shows a temperature dependence of $\text{H}{}_{\mathrm{<mtext>eff</mtext>}}\text{(0)[1 ? B}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{(T/T}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{? C}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{(T/T}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{? …]}$ indicative of the existence of spin wave excitations. The values of $\text{B}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{C}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ are found to be 0.40 and 0.06, respectively, for T/T_c ? 0.72. At temperatures close to T_c, H_eff(T) varies as (1 ? T/T_c)^β where β is one of the critical exponents and its value is found to be 0.29 ± 0.02.     

Effects of oblique-incidence evaporation on magnetic properties of Fe20Ni80/Fe70Co30 bilayer film

Evaporative deposition at oblique incidence is shown to enhance the magnetic anisotropy of an Fe₂₀Ni₈₀ magnetic film and induce magnetic anisotropy in an overlying, strongly isotropic Fe₇₀Co₃₀ film. This deposition method for the formation of an underlayer of several lattice parameters in thickness and semi-hard overlayer of a few thousands Angstroms in thickness achieves a significant change in the magnetization process and strong suppression of the coercive forces of Fe₇₀Co₃₀ in the hard magnetization direction. Soft magnetization of the Fe₇₀Co₃₀ overlayer is not achieved when one of the layers is deposited at oblique incidence. It is anticipated that shape magnetic anisotropy is responsible in part for the magnetic anisotropy induced in both in Fe₂₀Ni₈₀ under- and Fe₇₀Co₃₀ overlayer by oblique incidence evaporation.     

非晶态合金Fe83B17和Ni64B36结构的研究

本文叙述了用偏振中子衍射方法对Fe₈₃B₁₇非晶合金和中子衍射方法对Ni₆₄B₃₆非晶合金的结构研究。由实验数据计算了每种合金的偏干涉函数(PSF)S_ij(Q),和偏简约径向分布函数G_ij(r)。并得到原子短程结构上的各项参数。在此基础上,讨论了这一类非晶态合金的结构模型,计算了其一种模型简单单元的中子衍射散射强度,并和实验所得的结果作了比较。 关键词：     

Studies of the relaxed amorphous phase in the Fe80Nb6B14 alloy

The paper presents measurements of magnetic permeability, magnetic after-effects, magnetostriction, DSC and XPS for the Fe₈₀Nb₆B₁₄ amorphous alloys preliminary annealed for 1 h at temperatures ranging from 300 to 770 K. It was shown that annealing out of free volume and internal stresses causes a decrease of magnetostriction coefficient and leads to the formation of the energetically stable relaxed amorphous state. The XPS spectra show local fluctuation of boron density. This effect was attributed to the formation of small iron clusters—the characteristic feature for the relaxed amorphous phase.     

退火诱导亚稳态Fe80Cu20合金固溶体的结构相变

利用扩展x射线吸收精细结构和x射线衍射研究了机械合金化制备的体心立方(bcc)的亚稳态Fe₈₀Cu₂₀合金固溶体的结构随退火温度的变化特点.结果表明，在300—873 K温度范围内，随着退火温度的升高，bcc结构物相的晶格常数近于线性降低，这主要是由于Cu原子从bcc结构Fe₈₀Cu₂₀合金固溶体中逐渐偏析出来，生成面心立方(fcc)结构的Cu物相所致.经603K退火后，Cu原子的平均键长R_Cu—Cu增加了0.003 nm左右，大约有50%的Cu原子从bcc结构的Fe₈₀Cu₂₀合金固溶体中偏析出来.在773 K退火后，bcc结构Fe_８０Cu₂₀合金固溶体近于完全相分离，生成了bcc结构的α-Fe与fcc结构的Cu物相. 关键词： 扩展x射线吸收精细结构 x射线衍射 ８０Cu₂₀合金')" href="#">Fe_８０Cu₂₀合金 机械合金化     

Magnetic thermoelectric power of Fe20Ni60B10Si10 metallic glass

The magnetic contribution to the thermoelectric power was separated for the metallic glass Fe₂₀Ni₆₀B₁₀Si₁₀ which exhibits the ferro-paramagnetic transition at T_c = 455 K remarkably below the crystallization threshold T_x = 670 K. Results are compared with the predictions of the Kasuya theory.     

Changes in the hyperfine interactions in the Fe80Nb3Cu1B16 metallic glass under tensile loading

The influence of tensile stress on the changes in hyperfine parameters obtained by Mössbauer spectroscopy of the ferromagnetic amorphous NANOPERM-type Fe₈₀Nb₃Cu₁B₁₆ alloy has been investigated. The bulk changes are obtained by Mössbauer spectroscopy in a transmission geometry using γ-rays; the surface properties are studied in a scattering geometry using conversion electrons. The Mössbauer spectra are analyzed by two distributions of hyperfine inductions, which result in high-field and low-field components corresponding with a model of clusters formed by predominantly iron atoms and intermediate phase containing mainly the Nb, Cu and B atoms. The obtained results are completed by the bulk and surface magnetic measurements, with observations of surface morphology by AFM and microstructure by SEM. The investigations yield approximately linear increase of hyperfine parameters and slight deterioration of the bulk as well as surface magnetic characteristics with tensile loading.     

Structural transformations and magnetic properties of Fe60Pt15B25 and Fe60Pt25B15 nanocomposite alloys

Structural and magnetic properties of two rapidly solidified and post-annealed Fe₆₀Pt₁₅B₂₅ and Fe₆₀Pt₂₅B₁₅ alloys are compared. The as-quenched Fe₆₀Pt₁₅B₂₅ ribbon was fully amorphous whereas in the Fe₆₀Pt₂₅B₁₅ alloy the amorphous phase coexists with an fcc FePt disordered solid solution. Differential scanning calorimetry curves of both alloys reveal a single exothermal peak with onset temperatures of 873 and 847 K for Fe₆₀Pt₁₅B₂₅ and Fe₆₀Pt₂₅B₁₅, respectively. Magnetically hard, tetragonal ordered L1₀ FePt and magnetically soft Fe₂B nanocrystalline phases were formed due to the annealing of the alloys, as indicated by X-ray diffraction and Mössbauer spectroscopy measurements. Two-phase behavior was detected in the temperature dependence of magnetization of the annealed samples. A magnetic hardening was observed for all annealed ribbons. Magnetic properties of the annealed alloys, studied by hysteresis loop measurements, were related to the differences in the relative fractions of the hard and soft magnetic phases calculated from Mössbauer spectra. The alloy with 25 at% Pt exhibits better hard magnetic properties (H_c=437 kA/m, M_r/M_s=0.74) than the alloy with smaller Pt content (H_c=270 kA/m, M_r/M_s=0.73) mainly due to the larger abundance of the ordered tetragonal FePt phase.