热处理对(Fe_(0.52)Co_(0.30)Ni_(0.18))_(73)Cr_(17)Zr_(10)非晶合金的组织结构及磁性能的影响

采用单辊急冷法制备(Fe_(0.52)Co_(0.30)Ni_(0.18))_(73)Cr_(17)Zr_(10)非晶薄带,并对该合金进行等温退火。采用XRD,AFM,VSM研究退火温度对(Fe_(0.52)Co_(0.30)Ni_(0.18))_(73)Cr_(17)Zr_(10)非晶合金的组织结构和磁性能的影响。结果表明:非晶合金晶化过程为Am→α-Fe(Co)+Am′→α-Fe(Co)+Cr_2Ni_3+Fe_3Ni_2+Cr_2Zr+未知相。当退火温度Ti玻璃转变温度Tg时,由于结构弛豫、内应力的释放,合金的饱和磁化强度Ms有所提高;当晶化起始温度TxTi第一晶化峰值温度Tp1时,由于铁磁性α-Fe(Co)相的析出,Ms显著提升;当TiTp1时,由于晶粒长大和第二相的析出,Ms急剧恶化,565℃退火能够获得最好磁性能(Ms=106.8A·m~2·kg~(-1))。490℃和565℃退火后薄带表面的AFM观察表明,AFM图片所呈现的颗粒尺寸要比用Scherrer法测得的α-Fe(Co)纳米晶尺寸大得多,这是典型的包裹晶粒现象。     

Structural and magnetic behaviour of soft magnetic Finemet-type ribbons

Different kinds of magnetic anisotropies have been induced during the nanocrystallization process of Co- and Ni-rich amorphous ferromagnetic (Finemet) ribbons by the application of a constant stress or an axial magnetic field during the annealing process. Magnetization measurements have evidenced the presence od macroscopic anisotropy in the treated samples. The main goal of this work has been, after a careful DSC study, the structural analysis of the treated ribbons using X-ray Diffraction and Atomic Force Microscopy (AFM), detecting substantial differences in the crystallization state and grain size of the samples depending on the thermal treatment that was carried out. Moreover, AFM measurements revealed in all the treated samples a strong nanocrystallisation of the surface without evidences of amorphous matrix, which contrast with XRD measurements that have shown a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements have been performed with the aim to elucidate the complex magnetic behaviour that is expected for the surface of the ribbons, measuring surface hysteresis loops that showed much higher coercive field values than that obtained in the bulk material.     

High Magnetic Field Annealing Dependent the Morphology and Microstructure of Nanocrystalline Co/Ni Bilayered Films

Co/Ni bilayered films were prepared on ITO glass by electrodeposition assisted with a magnetic field up to 0.5T aligned parallel to the electrode surface. The effect of a high magnetic field annealing up to 12T on morphology and microstructure of the post-deposited films was investigated by field emission scanning electronic microscopy (FE-SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). Grain shape and grain boundary in the Co/Ni morphology were modified dramatically when the high magnetic field was applied during the annealing process. Magnetic anisotropy appeared in the films due to the preferential orientation of fcc-CoNi alloy in comparison with a weaker orientation of hcp-Co. High magnetic field annealing favored to form a more homogeneous surface with smaller grain size and lower roughness, compared with the annealed samples obtained in the absence of magnetic field. The influencing mechanisms of high magnetic field annealing on the microstructure evolution in the Co/Ni electrodeposits are interpreted in terms of the overlapping effects: diffusion, recrystallization, grain growth and magnetic domains.     

Fe77Co2Zr9B10Cu2合金的制备及其磁性能

采用单辊快淬法制备了Fe77Co2Zr9B10Cu2合金,在530～750℃等温退火40 min,利用X射线衍射和振动样品磁强计研究了Fe77 Co2 Zr9 B10 Cu2合金的微观结构和磁性能。结果表明:淬态Fe77Co2Zr9B10Cu2合金为非晶、纳米晶双相结构。随着退火温度的升高,α-Fe晶体相从非晶、基体中析出,晶粒尺寸长大,晶化体积分数增加,矫顽力先减小后增大,比饱和磁化强度逐渐增大。实验结果表明,530℃退火后合金的矫顽力最小,在670℃时迅速增大。样品的磁性与其微观结构、晶粒尺寸、晶化体积分数等因素有关.     

Corrosion behaviour and magnetic properties of melt-spun Nd-(Fe·Co·Ni)-B-(Al·Ti) ribbons

The corrosion behaviour of melt-spun Nd-Fe-B alloy ribbons in which Fe was replaced with Co and Ni and small quantities of Al and Ti added was investigated from the viewpoint of anodic corrosion, Although the addition of Ni degraded the magnetic properties of melt-spun ribbons, it improved corrosion resistance. According to EDXS and AES analyses, the corrosion products on the surface of Ni-free ribbons consisted of Nd and Fe oxides, but the Nd oxide corrosion product almost disappeared in the Ni-added samples. Also, the degradation of magnetic properties after the corrosion test was suppressed by the addition of Ni.From these results, it was thought that the improvement of corrosion resistance and the smaller degradation of magnetic properties of Nd-(Fe·Co·Ni)-B-(Al·Ti) ribbons after the corrosion test were associated with the suppressed dissolution of the Nd-rich phase at the grain boundaries.The oxidation of Ni-added melt-spun ribbons also showed similar characteristics and behaviour to the corrosion test in the morphologies of the ribbon surface and magnetic properties after the oxidation test.     

Co_(0.5)Zn_(0.5)Fe_2O_4/SiO_2磁性纳米复合粉体的制备

采用溶胶-凝胶法以正硅酸乙酯和金属硝酸盐分别作为SiO2和铁氧体的前驱体成功制得Co0.5Zn0.5-Fe2O4/SiO2磁性纳米复合粒子.利用XRD、DSC-TG、Raman和SEM研究了热处理温度和酸添加量对样品晶体结构和晶粒尺寸的影响,并用谢乐公式估算平均晶粒尺寸.最后用振动样品磁场计(VSM)对样品的磁性能进行检测.结果表明,随热处理温度的升高,样品由非晶态转变成SiO2基体中结晶较完整的尖晶石结构的单相铁氧体纳米晶,晶粒尺寸为12.65nm.晶粒尺寸随热处理温度的升高和酸添加量的增加不断变大.对材料的磁性能的研究结果表明,合成的纳米Co0.5Zn0.5Fe2O4/SiO2,其比饱和磁化强度为9.17emu/g,矫顽力为67Oe.     

FeCoBSiNb (Y)合金的玻璃形成能力及磁性能研究

采用铜模真空吸铸法、X射线衍射仪(XRD)、示差扫描量热分析仪(DSC)及振动样品磁强计(VSM),研究稀土元素Y及Fe/Co比例变化对FeCoBSiNb(Y)系合金的玻璃形成能力、热稳定性及磁性能影响.实验结果表明,添加4%(原子分数)的Y有利于(Fe0.5 Co0.5)72B19.2 Si4.8Nb4合金玻璃形成能...     

热处理对Fe_(79.5)P_(12)C_6Cu_(0.5)Mo_(0.5)Si_(1.5)软磁合金薄带的巨磁致阻抗效应(GMI)的影响

研究了不同温度热处理对Ｆｅ７９．５Ｐ１２Ｃ６Ｃｕ０．５Ｍｏ０．５Ｓｉ１．５的巨磁阻抗的影响，发现ＧＭＩ不仅与磁导率有关，而且也受到磁各向异性的作用。     

Anisotropic Magnetoresistance Effect in Amorphous and Nanocrystalline Fe(Cu,Nb)-Si-B Alloys

1. IntroductionRecent works on the properties of Fe-basednanocrystalline alloys have generated considerable interest in the filed of materials because of their excellent soft magnetic characteristi.s[1'21. As a newlydeveloped material, the origin of the excellent softmagnetic characteristics was not clear yet. H..z.r[3]et al. have suggested that smaller magnetic crystallineanisotropy is one of the most important factors whichdominate the excellent soft magnetic characteristics,but the explanat…     

纳米晶复合Nd9.5Fe81-xCoxZr3B6.5永磁材料磁性能的研究

采用熔体快淬及晶化退火工艺制备了Nd9.5Fe81-xCoxZr3B6.5(x=0、2、5、8、10)纳米晶合金条带,研究了Co的添加对快淬合金磁性能和居里温度的影响.结果表明,适量Co元素的添加能够有效降低各相晶粒的尺寸,增强了软、硬磁相晶粒的交换耦合作用,从而提高了合金的磁性能.Co含量为5%(原子分数)的合金,经670℃/4min的晶化处理后所得到的最佳磁性能为`Br=0.90T,jHc=588kA/m,(BH)max=117kJ/m3.     

The Influence of Annealing Temperature on the Magnetic Properties of Mn0.5Co0.5Fe2O4 Nanoferrites Synthesized via Mechanical Milling Method

Mn_0.5Co_0.5Fe₂O₄ nanosized ferrites have been made directly from MnFe₂O₄ and CoFe₂O₄ ferrites and from metal oxides by using high-energy ball milling. Single-phase formation and microstructure of the as-milled samples and samples annealed at 100, 200, 300, 400 and 500 ^°C under argon atmosphere were studied using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average grain sizes were estimated from XRD measurements and found to be between 7 and 11 nm. The microstrain for each sample was relieved by annealing due to crystallite growth. Room temperature magnetic properties were investigated by zero-field ⁵⁷Fe Mössbauer spectroscopy and vibrating sample magnetometer (VSM). Saturation magnetizations of the samples were estimated using the empirical law of approach to saturation. The variation of coercive field, saturation magnetization, maximum magnetization and remanent magnetization for each sample was found to depend on the annealing temperature. The coercive fields are observed to increase with increased annealing temperature (from about 300 Oe for the as-milled samples to about 1000 Oe for samples annealed at 500 ^°C) which we attribute to increases in grain sizes.     

低温应力退火Fe基合金薄带巨磁阻抗特性的研究

通过同步辐射X射线衍射技术,观测Fe73.5Cu1Nb3Si13.5B9非晶薄带经过不同温度和不同应力退火60 min后样品的微观结构,利用HP4294A型阻抗分析仪测量相应样品的巨磁阻抗比与磁各向异性。研究结果表明,在450℃下施加不同应力退火的样品仍然处于非晶结构状态,并且在应力为112.1 MPa的条件下产生优异的磁性能,样品的最大巨磁阻抗比达到了1818.7%,是自由退火条件下最大巨磁阻抗比的1.9倍,同时能够改变巨磁阻抗曲线的形状,使Fe基合金薄带的巨磁阻抗曲线具有宽线性的特性。对实验数据进行拟合后发现,样品的最大巨磁阻抗比和磁各向异性场与外加应力都具有线性关系,磁感灵敏度与外加应力具有负指数关系。通过探究发现具有非晶结构的Fe基合金薄带的磁学性能对应力敏感,可以作为研究非晶纳米晶合金材料应力敏感问题的另一个新方向。     

Further investigations on martensites in Fe-0.5 wt% C and Fe-0.5wt% C-24 wt% Ni melt spun ribbons

The types of martensites occurring in Fe–C and Fe–Ni–C melt spun ribbons in the as-solidified and after heat treatment conditions has been investigated using transmission electron microscopy. It has been found that melt spinning of Fe–0.5 wt% C induces a dislocated martensitic structure at room temperature even for grains as fine as 3m. The martensite laths are separated by thin layers of retained austenite. The martensite/austenite orientations are controlled by both the K-S and N-W relationships. Some of the martensite laths exhibit a twin relation. The dislocations within the laths are mainly screw. The counterpart alloy, Fe–0.5 wt% C–24 wt% Ni exhibits 100% austenite under similar conditions. Increasing the austenite grain size upon annealing enhances martensitic transformation. The present work is concentrated on the details of butterfly martensite obtained in these ribbons.     

快淬铜钴镍合金的晶体结构及其颗粒形貌研究

利用熔体快淬法制备了的铜钴镍合金材料Cu95-xCoxNi5（x=0,7,13,15,19,25,31）。利用场发射扫描电子显微镜及其X射线能谱附件研究了样品表面形貌以及颗粒和背景区域的Co／Ni／Cu含量比。利用X射线衍射研究了样品的晶体结构。发现样品具有面心立方结构,其晶格常数比Ni大,略小于Cu;样品表面存在着大量小颗粒,多数颗粒粒径分布在10-30nm之间,X射线能谱给出颗粒附近区域Co含量明显高于无颗粒区域。     

Magnetic and magnetocaloric properties of nanocrystalline Pr(1-x)A(x)Mn(1-y)Co(y)O3 (A = Ca, Sr) (x = 0.3; y = 0.5) manganites

Structural, magnetic and magnetocaloric properties of sol-gel prepared, nanocrystalline oxides Pr(1-x)A(x)Mn(1-y)Co(y)O3 (A = Ca, Sr) (x = 0.3; y = 0.5) (cubic, space group Fm3m) have been studied. From the X-ray data, the crystallite size of Pro.7Ca0.3Mn0.5Co0,503 and Pr0.7Sr0.3Mn0.5Co0.5O3 samples is found to be approximately 24 nm and approximately15 nm respectively. High resolution transmission electron microscopy image shows average particle size of approximately 34 nm and approximately 20 nm. Magnetization measurements indicate a Curie temperature of approximately 153 K and approximately172 K in applied magnetic field of 100 Oe for Pr0.7Ca0.3Mn0.5Co0.5O3 and Pr0.7Sr0.3Mn0.5Co0.O3 compounds. The magnetization versus applied magnetic field curves obtained at temperatures below 150 K show significant hysteresis and magnetization is not saturated even in a field of 7 T. The magnetocaloric effect is calculated from M versus H data obtained at various temperatures. Magnetic entropy change shows a maximum near T(c) for both the samples and is of the order approximately 2.5 J/kg/K.     

Microstructure of Differently Annealed NanocrystallineFe_(72.7)Cu_1Nb_(1.8)Mo_2Si_(13)B_(9.5) Alloy

The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.     

添加Zr、Co、B元素对ThCu_7型Sm-Fe合金结构的影响

采用SEM、XRD、EDX等方法分析了添加合金元素B、Zr、Co前后Sm-Fe合金铸锭的微观结构及快淬条带中的相组成.研究表明,添加合金元素B、Zr、Co前后,Sm-Fe合金铸锭均由Sm2Fe17相、富Sm相和α-Fe相组成,添加B可促使铸锭晶粒细化,富Sm相由块状向条状变化,添加Zr、Co可使铸锭晶粒进一步细化,富Sm相进一步条状化.添加合金元素B、Zr、Co前,Sm-Fe合金仅在快淬速度达到30m/s时得到ThCu7型六角晶结构的Sm10Fe90相及少量α-相;添加B、Zr、Co元素后,在不同快淬速度下合金均可得到单一的ThCu7型六角晶结构的Sm10Fe90相及部分非晶相.添加Zr、Co元素后,快淬条带晶粒进一步细化.当Zr、Co元素含量一定时,随快淬速度的加快,其晶胞体积呈先升后降的趋势,同时快淬条带中的非晶相逐渐增加,Sm10Fe90相逐渐减少.     

应力作用下电流退火对钴基非晶薄带的巨磁阻抗效应的影响研究

采用应力作用下的直流电流退火处理Co68.2Fe2.3Mo2Si12.5B15非晶薄带，详细讨论了应力退火前后Co基薄带的巨磁阻抗效应的变化，以及退火时间对巨磁阻抗效应的影响，研究表明：应力作用下的电流退火有利于巨磁阻抗效应的提高，并可以通过控制退火时间控制阻抗与外场变化关系曲线形状。     

电脉冲快速退火Fe73.5Cu1Mo3Si13.5B9合金的组织与磁性能

采用电脉冲快速退火实现了非晶合金Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５的纳米晶化。显微组织分析与磁性能测定结果表明,该合金经适当工艺的脉冲电流处理可得到较常规法晶粒密度更高、晶粒尺寸更小、软磁性能更优的纳米晶材料。基于随机无规磁各向异性模型,阐明了该合金的软磁性能与其显微结构的关系。     

电脉冲快速退火Fe_(73.5)Cu_1Mo_3Si_(13.5)B_9合金的组织与磁性能

采用电脉冲快速退火实现了非晶合金Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９的纳米晶化。显微组织分析与磁性能测定结果表明,该合金经适当工艺的脉冲电流处理可得到较常规法晶粒密度更高、晶粒尺寸更小、软磁性能更优的纳米晶材料。基于随机无规磁各向异性模型,阐明了该合金的软磁性能与其显微结构的关系