金属玻璃(Fe_(0.8)Ni_(0.15)Cr_(0.05))_(78)Si_8B_(14)的起始磁导率减落现象

在77—553K范围内的不同温度下测量了金属玻璃(Fe_(0.8)Ni_(0.15),Cr_(0.05))_(78)Si_8B_(14)的起始磁导率减落。测量结果表明,减落的温度关系表现为一个具有单一弛豫峰的不对称谱。在273K下考察了减落的动力学行为。用Hesse-Rubartsch方法拟合动力学曲线得到一个左右不对称的单峰激活能谱,最可几激活能大约为1.40eV。考察了减落的退火效应及退火动力学行为,结果表明,在宽的温度范围内,减落呈现明显的退火效应,而且退火动力学行为近似服从lnt动力学。     

金属玻璃(Fe1-xCox)78Si10B12的感生各向异性

本文研究了金属玻璃(Fe_1-xCO_x)₇₈Si₁₀B₁₂的磁化感生各向异性、应变感生各向异性随成分和温度的变化。磁化感生各向异性常数K_um为正值,x=0.7时为最大;不可逆的应变感生各向异性常数K_usi为正值,x=0.5时为最大;可逆的应变感生各向异性常数K_usr除了x>0.975区均为负值,在x=0.7时为最大;感生各向异性常数在温度变化时与M_s^α成正比,α在3.4和7.5之间随成分和退火工艺而变化。用短程有序模型解释了部分实验结果。 关键词：     

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：     

(Fe0.1Co0.55Ni0.35)78Si8B14金属玻璃的晶化过程及压力的影响(Ⅰ)——晶化时的相析出过程

用X射线衍射法研究了(Fe_0.1Co_0.55Ni_0.35)₇₈Si₈B₁₄金属玻璃在常压下及20kbar高压下晶化过程中的析出相及析出过程。结果表明在上述压力下晶化过程都分成两个阶段,分别对应于初级晶化和共晶晶化。在常压下,初级晶化时析出fcc-Co晶体,而共晶晶化对应着Ni₃₁Si₁₂和(FeCoNi)₃(SiB)相的析出。随着回火温度的增高或时间的延长,(FeCoNi)₃(SiB)相逐渐转变为(FeCoNi)₂₃B₆相。20kbar高压下的晶化析出过程与常压下不同的是:提高了晶化温度,在共晶晶化阶段出现了Co₂B相。此外,压力还阻止(FeCoNi)₂₃B₆相的形成。从热力学和动力学的角度讨论了压力对金属玻璃晶化过程的影响。 关键词：     

非晶(Fe0.99Mo0.01)78Si9B13,Fe78Si9B13合金激波晶化主相α-Fe变化研究

研究激波对非晶FeBSi,FeMoBSi合金的影响,经X射线衍射分析,测定主晶化相α-Fe(Mo,B,Si)晶格常量.结果表明：晶格常量比正常值偏小,用双势模型计算晶格常量,理论值与实验符合得很好.从而肯定晶格常量变小是形成B的替代式固溶体和缺位式固溶体所致. 关键词：     

纳米微晶Fe69.5(CuCrV)9.5Si13B8超铁磁性研究

经813K温度退火后的纳米微晶Fe_(?)(CuCrV)_(9.5)Si_(13)B_8由α-Fe(Si)晶粒和晶界两种磁相组成,温度从10—8l3K的穆斯堡尔研究显示晶粒的超精细场随着温度的变化曲线上有一个转折.用超铁磁性模型进行拟合,结果表明晶界和晶粒间存在强的交换耦合作用,使晶粒的有效磁各向异性常数减小为原来的六分之一. 关键词：     

由观测无胁强作用下的热膨胀和电阻研究金属玻璃(Fe0.85Ni0.15)84B16的结构弛豫

本文通过长度、电阻和热膨胀系数的测量研究了(Fe_0.85Ni_0.15)₈₄B₁₆金属玻璃结构弛豫和退火温度T_a的关系。基于上述物理量对结构弛豫的关系,对曲线作了分析和讨论。在退火温度为175℃至250℃之间结构弛豫随T_a的变化率最大。 关键词：     

(Fe0.1Co0.55Ni0.3578Si8B14金属玻璃的晶化过程及压力的影响(Ⅱ)——晶化温度和晶化激活能

本文用高压下原位电阻测量法研究了3GPa以下(Fe_0.1Co_0.55Ni_0.35)₇₈Si₈B₁₄金属玻璃的晶化温度T_x,并用Kissinger法求得不同压力下金属玻璃的晶化激活能△E_x。测量结果表明,施加压力时这种合金的T_x并不是单调地、更不是线性地升高的,而是在上升的总趋势中还存在某些局部的转折。这和一些被广泛引用的结论是不同的。晶化激活能△E_x也随压力作类似趋势的变化。分析认为,压力促进晶化时的成核过程,而抑制晶核的扩散性长大。两者的综合作用是造成△E_x、从而也构成T_x非单调变化的原因。压力除了通过△E_x影响T_x以外,指数前因子的压力效应也可以使晶化温度产生重要的改变。 关键词：     

非晶Fe82Si5B13合金的磁导率驰豫

在0—300℃范围内考查了非晶Fe₈₂Si₅B₁₃合金的磁导率等温弛豫动力学行为,给出了等时弛豫谱,观察到四个弛豫峰。测量表明,总的磁导率弛豫由两种弛豫过程组成,即对于退磁可逆的普通减落和对于退磁不可逆的磁导率连续衰减。计算了弛豫时间和激活能的分布,表明弛豫时间和激活能有宽的分布。普通减落和磁导率衰减过程的最可几激活能分别为1.0eV和1.4eV。对退火的样品,观察到磁导率先是增大而后是衰减的广义cross-over效应。 关键词：     

非晶态(Fe1-xCox)78Si9.5B12.5合金的X射线光电子能谱研究

本文报道非晶态(Fe_1-xCo_x)₇₈Si_9.5B_12.5合金的X射线光电子能谱的实验结果,分别给出了Fe,Co,Si,B元素的内层电子能级的结合能以及费密面态密度随Co含量的变化关系。 关键词：     

Magnetic phase transition in (Mn0.95Ni0.05)3B4

It was found that the metallic compound (Mn_0.95Ni_0.05)₃B₄ was ferromagnetic below 195 K and antiferromagnetic between 195 and 354 K. The transition temperature from ferromagnetic to antiferromagnetic increases with increasing external magnetic field. On the other hand, the transition temperature from antiferromagnetic to paramagnetic decreases with increasing magnetic field. It is expected that the present results might be explained by the theoretical results on the coexistence of ferro- and antiferromagnetism in the itinerant electron system reported by Moriya and Usami.     

非晶合金Fe78Si9B13在脉冲电流作用下的单相晶化

对非晶合金Fe₇₈Si₉B₁₃进行了超短脉冲电流处理，实现了晶化时α-Fe（Si）单相结构析出．可以认为，脉冲电流作用时，电子运动与非晶中空位型结构缺陷间的周期性排斥效应促进了类金属原子从非晶结构单元中析出，使Fe（Si）原子局部富集，导致基体金属相在较低温度下优先成核．而在空位的定向迁移的同时，将伴随B原子的扩散，则B原子局域富集，Fe-B化合物的形核析出就要受到这两个因素的抑制 关键词：     

Patterning of amorphous and polycrystalline Ni78B14Si8 with a focused-ion-beam

The machining response of amorphous and crystalline Ni₇₈B₁₄Si₈ was investigated when structuring substrates using focused-ion-beam (FIB) milling. In particular, the sputtering yield as a function of the scan speed, and the effects of ion fluence and scan speed on the milled depth were studied. The ion fluence dependent evolution of the cross-sectional profiles of trenches was examined by atomic force microscopy (AFM). When milling amorphous Ni₇₈B₁₄Si₈, it was found that the sputtering yield first decreased with increasing the beam scan speed, then kept constant within the scan speed range, up to 710 nm/s, investigated in this work; it was also found that the milled depth was almost proportional to the ion beam fluence. The patterning of polycrystalline Ni₇₈B₁₄Si₈ resulted in anisotropic milling-rates due to the varying orientation of the grains in the material. The analysis of the profile evolution in both materials indicated that the surface finish of trenches was scan speed, ion beam fluence and scan strategy dependent. The study demonstrated that direct patterning by FIB could be used for producing masters in amorphous Ni-based alloys for injection moulding and hot embossing.     

Critical phenomena of amorphous Nd4(Fe0.75Cr0.25)77.5B18.5 alloys

The magnetic behavior of amorphous Nd₄(Fe_0.75Cr_0.25)_77.5B_18.5 alloys was investigated in the critical region. The Curie temperature T_C and critical exponents β, γ and δ are found to be 141 K, 0.45±0.02, 1.64±0.08 and 4.66±0.10, respectively. The data are fitted to a magnetic equation of state characteristic of a second-order phase transition over a rather wide range of temperatures both above and below T_C. It is noted that the values of the exponents are in disagreement with those derived for a three-dimensional Heisenberg ferromagnet and show an enhancement. This anomalous critical behavior may originate from magnetic inhomogeneity.     

Critical behavior of Fe15Ni65B18Si2 ferromagnetic glass

AC susceptibility, magnetization and electrical resistivity around the Curie temperature (T_c) were measured for Fe₁₅Ni₆₅B₁₈Si₂ glass. The results yield T_c = (307.6±0.1) K and the following critical exponents γ = 1.50±0.03, β = 0.375±0.01, δ = 5.1±0.1 andα = -0.29±0.05. These values were obtained in the reduced temperature interval $\text{1×10}{}^{-3}\text{?}\text{|T?T}{}_{\mathrm{c}}\text{|}\text{T}{}_{\mathrm{c}}\text{?5 ×10}{}^{-2}$. In spite of the fact that these values for the critical exponents were obtained from different measurements they obey the equality relations γ = β(δ?1) and γ+2β+α = 2. Reduced magnetisation and field follow a magnetic equation of state derived for a second-order phase transition over a wide temperature range. This set of critical exponents is compared with those derived from the Heisenberg model as well as with the usual ones for a pure crystalline ferromagnets. The comparison shows that the values of |α| and γ, for our alloy, are considerably larger than those from the model and the usual crystalline ones. A similar difference is also observed in some other amorphous and dilute crystalline ferromagnets and is probably due to magnetic inhomogeneities.