Fe基非晶态合金的低温电阻研究

本文报道Fe_100-xB_x,Fe_87-xSi_xB₁₃,(Fe_1-xCo_x)₇₈Si_9.5B_12.5,(Fe_1-xM_x)_80-84B_16-20(M=Zr,V,Nb,Ta,Cr,Mo,W,Mn)非晶态合金的 关键词：     

铁基非晶合金磁致伸缩的温度效应

本文研究了Fe_80-xCu_xSi₅B₁₅,(Fe_1-xCo_x)₈₂Cu_0.4Si_4.4B_13.2两系列非晶合金的磁致伸缩系数λ₄随温度T的变化关系,温度范围分别为室温至非晶态居里点和室温至晶在居里点。分析了Fe基非晶合金随温度变化所产生的结构变化,并讨论了其磁致伸缩的单离子微观机制。 关键词：     

成分和过渡金属对FeZr基非晶态合金晶化温度的影响

本文系统研究了Fe_100-xZr_x,(Fe_1-xZr_x)₈₄B₁₆和Fe_90-xM_xZr₁₀(M=V,Cr,Mn,Co,Ni,Si,B)非晶态合金的晶化温度与成分的关系。主要结果有:用Zr替代Fe使晶化温度明显提高;在FeMZr非晶态合金系列中,晶化温度依M=Mn,Cr,V元素的顺序和M含量x的增大而提高,而依 关键词：     

非晶态Fe90-xMnxZr10合金的磁性

本文报道用单辊急冷方法制备的非晶态合金Fe_90-xMn_xZr₁₀(x=0,4,6,10,15)的磁性,讨论了样品中每个原子的平均磁矩和居里温度T_c随Mn含量x的变化以及类自旋玻璃特性,给出了非晶态Fe_90-xMn_xZr₁₀合金的磁相图。观察到非晶态Fe₈₄Mn₆Zr₁₀合金晶化后的热磁曲线 关键词：     

退火加热速度对Fe-Cu-Nb(V)-Si-B纳米晶合金磁性的影响

研究了退火温度为550℃的纳米晶化过程中加热速度对Fe_72.7Cu₁Nb₂V_1.8Si_13.5B₉与Fe_73.5Cu₁Nb₃Si_13.5B₉合金磁性的影响．磁性测量结果表明，退火加热速度对这两种合金软磁性能有明显的影响，快速加热可显著提高合金的初始磁导率μ_{i 关键词：}     

非晶Fe73.5Cu1Nb3Si13.5B9合金激光纳米化的超精细结构研究

在CO₂激光功率为50—300W、扫描速度为20mm/s、激光散光斑为20mm照射条件下 ，诱导非 晶Fe_735Cu₁Nb₃Si_135B9带中发生结构重组，产生定量纳米α-F e(Si)晶相形成双相组织结构材料. 利用穆斯堡尔谱研究了非晶Fe_735C u₁Nb₃Si_135B₉合金激光纳米化的 超精细结构. 实验结果表明，激光诱导非晶 Fe_735Cu₁Nb₃Si_135B ₉纳米化后，其超精细磁场的分布随 着激光功率变 化由单峰向双峰变化，在高功率辐照时， 出现了双峰分布，并且峰位向高场移动. 高激光 功率辐照非晶Fe_735Cu₁Nb₃Si_{135B9合金纳米晶化相有四种超精细结 构，即2个超精细磁场较小的初晶相和2个超精细磁场较大的纳米晶化相. 其中超精细磁场较 大(17—25MA/m)的α-Fe(Si)相为DO3结构. 关键词： 激光 纳米晶α-Fe（Si) 735}Cu₁Nb< sub>3Si_135B₉')" href="#">非晶Fe_735Cu₁Nb< sub>3Si_135B₉ 超精细结构 超精细磁场     

Fe73.5Cu1Nb3B9Si13.5非晶态合金的激波纳米晶化研究

实验表明,非晶态合金在激波影响下会转变为纳米晶.最近的实验进一步发现,Fe_73.5Cu₁Nb₃B₉Si_13.5非晶态合金中的Cu,Nb在激波晶化中的细化作用被抑制,且样品在这种转变之后作进一步的退火处理,其晶粒度变大而晶格常数变小.在激波晶化机理分析中提出了“激波流体晶化”构想. 关键词：     

非晶态FeZrB合金的电阻率与温度的关系

本文研究了非晶态(Fe_1-xZr_x)_84.5B_15.5(x=0,0.02,0.04,0.06,0.08,0.1,0.15)和Fe_90-xB_xZr₁₀(x=0,4,10,16,20)合金的电阻率ρ与温度T的关系。实验结果表明,当Zr含量在0.02≤x≤0.08时,ρ-T曲线出现两个线性斜率,在略高于居里温度T_c处出现转折,在T关键词：     

非晶态铁磁Fe-Ni基合金的穆斯堡尔谱研究

本文研究了非晶态合金Fe_81-xNi_xSi_3.5B_13.5C₂(x=5,10,15,20,25,30,35)及坡莫合金Fe₅₀Ni₅₀在室温和外加磁场下的穆斯堡尔谱,用拟谱方法获得了超精细相互作用的参量及超精细场分布P(H).实验结果表明,非晶态Fe-Ni基合金存在两种磁性铁原子且有类因瓦特性,在x=15左右存在异常现象.文中提出了外加磁场和低温的外界条 关键词：     

La3Co29-xFexSi4B10的择优占位、电子结构和晶格振动性质的理论研究

分别用第一性原理及原子间相互作用势对初始模型进行几何优化, 所得稳定结构的晶格参数均与实验值符合较好. 通过第一性原理密度泛函理论, 计算了稳定结构La₃Co_29-xFe_xSi₄B₁₀化合物择优占位情况, 计算结果表明, Fe原子最择优替代Co 原子的2c晶位, 择优占位顺序为2c > 8j1 > 8i2 > 8j2 > 8i3 > 16k > 8i1, 这与实验结果非常符合. Fe原子每次只替代不同晶位的一个Co原子时, La₃Co_29-xFe_xSi₄B₁₀ 体系的晶格常数几乎不变, 磁矩却发生了有趣的变化. 当Fe原子沿着择优顺序依次替代不同晶位的所有Co原子时, 随着La₃Co_29-xFe_xSi₄B₁₀体系中Fe原子含量的增多, 其电子态密度整体向左移动. Fe原子完全替代Co时, 与未掺杂时相比体系的总磁矩增加. 最后, 利用原子间相互作用势进一步预测了La₃Co_29-xFe_xSi₄B₁₀体系的晶格振动及热力学性质. 在低频部分, 振动模式主要由质量较大的Co, Fe和La元素作贡献; 随着掺杂原子Fe的增多, 体系的截止频率先减小后增多, 中频部分由Si元素引起的振动模式减少; B-B强相互作用引起了高频部分的振动模式. 基于声子态密度预测了不同数量Fe掺杂后体系的比热、熵和德拜温度的变化, 当Fe 含量大于Co时, 德拜温度明显升高.     

Partial crystallization of an amorphous alloy by electronic energy deposition

The first experimental evidence is reported of crystallization induced in an amorphous alloy by a high density of electronic excitation deposited along the path of swift heavy ions. The formation of nanocrystalline iron boride phases was observed in an amorphous Fe73.5Cu1Nb3Si13.5B9 alloy irradiated at low temperature with 5 GeV Pb ions up to fluences of 1 x 10(11) ions cm-2. No evidence for the formation of the Fe(Si) phase was found. This phenomenon was interpreted in terms of the relaxation of the high level of energy deposited in electronic excitations along the path of Pb ions in the target, which induces extensive stress and strain that could destabilize the amorphous structure.     

Microstructure and magnetic properties of Fe72.5Cu1M2V2Si13.5B9 (M=Nb, Mo, (NbMo), (MoW)) nanocrystalline alloys

The microstructure and magnetic properties of Finemet-type Fe_72.5Cu₁M₂V₂Si_13.5B₉ (M=Nb, Mo, (NbMo), (MoW)) alloys have been systematically studied. Results show that the nanocrystalline alloy with M=NbMo has the smallest grain size of about 8 nm. The order of the effect of Nb, Mo and W additions in decreasing the α-Fe grain size in nanocrystalline alloys is Nb>Mo>W. The best DC soft magnetic properties are obtained in the alloy with M=Nb. In the case of AC soft magnetic properties, the Nb alloy also exhibits a very low core loss comparing with typical Finemet alloy. Therefore, the Nb alloy is suitable for use as a transformer core material. In addition, it is shown that a narrow grain size distribution and a uniform dispersion of α-Fe grains in the amorphous matrix are very crucial for the development of new Finemet-type nanocrystalline alloys with good soft magnetic properties.     

Ga替代对纳米晶Nd(Fe,Co)B黏结磁体磁性能的影响

探讨了微量的Ga替代Fe对Nd₂(Fe,Co)₁₄B/(Fe,Co)₃B+(少量)α-Fe永磁材料的晶体结构及磁性能的影响,并讨论了双相纳米晶磁体性能的变化机理以及所适用的理论模型.结果表明,Ga的添加不仅使晶粒尺寸显著变小,而且在Ga含量x<1at%的范围,随着x的增加,B_r和(BH)_max随退火时间的变化关系由形似马鞍的曲线转化为抛物曲线;矫顽力_jH_c先下降到一个最小值后再上升;当x=0.2时,综合磁性能较好 关键词： 双相纳米晶磁体 快淬 退火 交换耦合 磁性能     

Magnetic Properties of Amorphous and Nanocrystalline Fe-Zr-B-Al Alloys

We have investigated the influence of aluminium substitution for iron on the magnetic properties of amorphous and nanocrystalline Fe_88-x Zr₇B₅Al _x alloys (x = 0, 1, 3, 5, 7 and 9 at.%). Thermomagnetic curves show an increase of Curie and crystallization temperature of amorphous phase with the increase of the content of aluminium in the alloy. The increase of aluminium content up to 3 at.% Al does not cause the decrease of a saturation magnetization in the as-quenched sample. In addition, magnetostriction of the annealed alloys has been studied. Also, the increase of aluminium content in the alloy causes an increase of the magnetostriction constant.     

Invar effects on some iron-base amorphous alloys

The thermal expansion and magnetic properties of Fe-B and Fe-P amorphous alloys prepared from melts have been investigated. These amorphous alloys show distinct Invar characteristics. heir magnetic properties are also very similar to those of Fe-Ni crystalline Invar alloys; that is, the high-field susceptability and forced-volume magnetostriction are remarkably large, the magnetic moment per Fe atom does not increase linearly, the Curie temperature decreases with a decrease in concentration of B or P, and their reduced their magnetization curves are much flatter than those of crystalline pure Fe.     

Study of structural and magnetic properties of Fe_(80)P-_9B_(11) amorphous alloy by ab initio molecular dynamic simulation

The structural and magnetic properties of Fe_(80)P_9B_(11) amorphous alloy are investigated through ab initio molecular dynamic simulation. The structure evolution of Fe_(80)P_9B_(11) amorphous alloy can be described in the framework of topological fluctuation theory, and the fluctuation of atomic hydrostatic stress gradually decreases upon cooling. The left sub peak of the second peak of Fe–B partial pair distribution functions(PDFs) becomes pronounced below the glass transition temperature, which may be the major reason why B promotes the glass formation ability significantly. The magnetization mainly originates from Fe 3d states, while small contribution results from metalloid elements P and B. This work may be helpful for developing Fe-based metallic glasses with both high saturation flux density and glass formation ability.     

预退火时间对Fe_(80.8)B_(10)P_8Cu_(1.2)非晶合金微结构及磁性能的影响

研究了预退火时间对Fe_(80.8)B_(10)P_8Cu_(1.2)非晶合金微结构及磁性能的影响.穆斯堡尔谱研究表明:在660 K的预退火温度下,随着预退火时间的增加,Fe原子不断富集,非晶基体中的类Fe_3B化学短程有序结构向类Fe B结构转变,并且非晶基体中Fe第一近邻壳层中Cu原子的逐渐脱离以及Fe-P配位键数量的明显减少可间接表征CuP团簇的形成过程.同时,本研究通过调节预退火时间来调控非晶基体中CuP团簇和Fe团簇的数量,促进后续退火晶化过程中α-Fe纳米晶相的析出,并细化纳米晶尺寸,从而获得综合磁性能更加优异的非晶/纳米晶软磁合金.     

STRUCTURE AND MAGNETIC PROPERTIES OF LaCo13-BASED ALLOYS

The structure and magnetic properties of two series of LaCois-based alloys, LaCo_13-xFe_x(0≤x≤6) and La_1-xR_x(Co, Fe)₁₃ (x=0.1,0.2; R=Y, Ge, Pr, Nd Sm, Gd, Tb, Dy, Ho, Er, and Yb), are studied by X-ray diffraction and magnetic mea- surements. In the above-mentioned composotions, all the samples display a structure of NaZn₁₃ type (space group: Fm3c). In LaCo_13-xFe_x system, as the iron content increases, its Curie temperature decreases, while thc magnetic moment per 3d atom increases. This may be explained by a rigid band model. In the other alloy system, the Curie temperature goes through a maxium at R=Gd, and this reflects the influ- ence of R - T interaction. It is also observed that saturation magnetization varies with R and gets lower when R is a heavy rare earth element. The contribution of R is close to that of a free-ion moment. La_0.9Pr_0.1Co₉Fe₄ has the largest value 29μ_B/f.u.     

Fe、Co、Ni混合团簇磁性的密度泛函研究

基于13原子二十面体结构,采用密度泛函方法系统计算研究了Fe、Co及Ni单质及二元混合团簇的磁性.发现有限温度下团簇磁性随结构畸变的敏感性随Fe、Co、Ni顺序逐渐减弱,同时发现二十面体结构Fe_(13)及Co_(13)均具有不同磁矩的近简并低能态.对FeNi及CoNi混合团簇、其磁矩随组分的变化不存在反常现象,但对于FeCo混合团簇、其磁矩随组分的演化行为存在个别反常现象.我们认为:这种反常现象能够对FeCo非晶合金中的实验观测结果提供一种可能的理论解释.     

NANOSTRUCTURED AND AMORPHOUS MATERIALS BY MECHANICAL ALLOYING

Mechanical Alloying is particularly attractive because it can be used to process structurally uniform and isotropic bulk quantities of powdered materials that have a fine length scale. Furthermore, it appears to be applicable to many combinations of elements. Here experimental results regarding the synthesis and characterization of several binary and ternary nanocrystalline and amorphous alloys of Ti, Zr, Hf, V, Nb and Fe with other transition elements and with B, C and Si are reported. The nanocrystalline and amorphous powders, with effective particle size between 7 and 30nm, were prepared by mechanical alloying in a high-energy ball-mill using commercial elemental powders and/or alloy powder.