纳米晶软磁材料的磁性能

介绍了纳米晶软磁材料所具有的独特结构和优异的磁性能。从纳米晶软磁材料的微观组织结构和宏观磁特性紧密相关的角度,探讨了铁基纳米晶合金的结构与磁性之间的依赖关系。     

不锈软磁合金研究

探讨了不锈软磁合金的产生、发展和应用。提出了开发不锈软磁合金、提高磁性能和耐蚀性的设计理念和方法。推荐了磁感应强度B25,电阻率ρ与合金成分关系的经验方程式。     

Balancing the strength and ductility of Mg-6Zn-0.2Ca alloy via sub-rapid solidification combined with hard-plate rolling

In this study,we successfully prepared a Mg-6Zn-0.2Ca alloy by utilizing sub-rapid solidification (SRS)combined with hard-plate rolling (HPR),whose elongation-to-failure increases from ～17 ％ to ～23 ％without sacrificing tensile strength (～290 MPa) compared with its counterpart processed via conven-tional solidification (CS) followed by HPR.Notably,both samples feature a similar refined grain structure with an average grain size of ～2.1 and ～2.5 μm,respectively.However,the high cooling rate of ～ 150 K/s introduced by SRS modified both the size and morphology of Ca2Mg6Zn3 eutectic phase in comparison to those coarse ones under CS condition.By subsequent HPR,the Ca2Mg6Zn3 phase was further refined and dispersed uniformly by severe fragmentation.Specially,the achieved supersaturation containing exces-sive Ca solute atoms due to high cooling rate was maintained in the SRS-HPR condition.The mechanisms that govern the high ductility of the SRS-HPR sample could be ascribed to following reasons.First,refined Ca2Mg6Zn3 eutectic phase could effectively alleviate or avoid the crack initiation.Furthermore,excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability during tension.The findings proposed a short-processed strategy towards superior performance of Mg-6Zn-0.2Ca alloy for industrial applications.     

新型耐蚀软磁合金的研制

新型耐蚀软磁合金,其化学成分为(质量分数,%)≤0.02C,13～18Cr,Si和/或Al 1～3,0.3～0.8Ti,0.003～0.03B,0.003～0.03Ce-La,同时含有或无0.4～3Mo和0.4～3Cu,余Fe.合金B25(H=25A/cm)≥1.15T,Hc≤48A/m,P0.75T/400Hz≤12W/kg(0.35mm冷轧带),电阻率ρ≥70μΩ·cm.按国军标GJB360.2-87规定的盐雾试验,96h无锈蚀.合金适于制作耐蚀航空微电机,汽车发动机电磁阀喷油器等耐蚀电磁元器件.     

经验电子理论在纳米晶软磁材料中的应用及展望

概述了固体与分子经验电子理论（简称EET理论）在一般材料和纳米晶软磁材料中的应用现状,提出了EET理论在纳米晶软磁材料应用中尚存在的问题,并给出了一些解决方案,最后展望了EET理论在纳米晶软磁材料中的应用前景。     

添加Ni对FeZrNbB合金的非晶形成能力与软磁性能的影响

利用单铜辊甩带法制备Fe(86-x)Zr2Nb2B10Nix(x=0、1、3和5)非晶合金带材。采用X射线衍射仪、差示扫描量热仪、振动样品磁强计以及精密磁性器件分析仪研究Ni元素对FeZrNbB合金带材的非晶形成能力和软磁性能影响。结果表明Ni元素能明显提高该体系合金的非晶形成能力,并使淬火态非晶合金带材的一级起始晶化温度提高;通过合金的退火处理,在Fe(86-x)Zr2Nb2B10Nix合金体系中含Ni元素的合金带材可以析出最小粒径为12(12.15)nm的α-Fe(a)纳米晶,获得较低的矫顽力为8.1A/m;其中Fe85Zr2Nb2B10Ni1非晶合金带材经过510℃保温20min热处理后可以获得较高的饱和磁感应强度为1.61T,有效磁导率提升到48.4k,矫顽力下降到8.3A/m。     

Si的添加对FeNiMoB合金非晶形成能力与软磁性能的影响

利用单铜辊甩带法制备Fe40Ni38Mo4B(18-x)Six(x=0,2,4,6,8,10和12)非晶合金带材,并用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、振动样品磁强计(VSM)以及精密磁性器件分析仪研究Si元素对Fe Ni Mo BSi合金带材的非晶形成能力和软磁性能影响。结果表明,随着Si元素的添加,合金带材的矫顽力Hc先减小后增大,并在x=4时最小为5.8 A/m;Fe40Ni38Mo4B14Si4合金带材在405℃保温10 min热处理后获得较高的饱和磁化强度为112.63 A·m2/kg,在345℃保温10 min热处理后获得较低的矫顽力为7.0A/m。     

Fe78Si9B13非晶合金磁芯封装及其软磁性能

研究了Fe78Si9B13非晶合金磁芯进行环氧封装及封装后对非晶合金磁芯软磁性能的影响。结果表明对磁芯进行环氧封装,有效改善磁芯的机械强度同时,能改善带材表面的平整度,在带材表面形成一层绝缘层,显著降低了非晶合金磁芯高频下的损耗值,封装后的非晶合金磁芯在Bm=1T,f=1kHz下,损耗值比封装前下降了14%。综合考虑机械强度大小、磁化难易、损耗高低等因素,封装胶浓度为2%时封装效果最佳。     

Fe-36%Ni软磁合金电沉积条件的研究

采用电沉积法制备Fe-36%Ni软磁合金薄膜,通过正交实验方法研究了Fe2 /Ni2 摩尔比、镀液pH值、电流密度、镀液温度与合金中铁含量的关系,用极差法分析了各工艺参数对Fe-Ni合金薄膜成分影响的显著性,并确定了最佳工艺条件.优化验证实验结果表明,所得合金薄膜光亮、致密、外观平整,合金薄膜中Fe含量为64.99%(质量分数),Ni含量为35.01%(质量分数),其饱和磁通密度(Bs)0.84T,剩余磁通密度(Br)0.27T,矫顽力(Hc)65A/m.     

Shape controlled synthesis of iron-cobalt alloy magnetic nanoparticles using soft template method

Fe_xCo_1 − x alloy nanoparticles of spherical (x = 0.25, 0.68, 0.85), hollow spherical (x = 0.60) and sheet like (x = 0.60) shapes were prepared at room temperature by reduction of iron chloride tetrahydrate and cobalt chloride hexahydrate with sodium borohydride, using N-Cetyl-N,N,N-trimethyl ammonium bromide (CTAB)/water/hexanol system as soft template. The size and shapes of nanostructures were found to depend on the concentrations of CTAB and hexanol in water. Composition and shape dependence of magnetic properties of spherical, hollow spherical and sheet like Fe_xCo_1 − x alloy nanostructures were discussed. The highest saturation magnetization of 235 emu/g with a coercivity of 160 Oe was obtained for spherical Fe_0.68Co_0.32 nanoparticles.     

热处理工艺对Finemet软磁合金高频磁性能影响的研究

利用XRD和TEM研究了Finemet非晶软磁合金的热处理诱发纳米晶化过程中的结构和组织形貌变化,利用Scherrer公式计算了晶化过程中产生的α-Fe颗粒的尺寸大小.由XRD及TEM的相关图谱表明,Finemet非晶软磁合金的晶化过程主要发生在500℃之后,当退火温度为560℃时,纳米晶化充分且晶粒分布均匀,合金材料具有优异的软磁性能.     

铁基纳米晶软磁合金的研究

本文主要评述了铁基纳米晶软磁合金的晶化过程、组织结构及其与磁性能之间的关系,分析了优异磁性能的起源,并详细论述了解释其优异磁性能的各向异性模型,提出了目前在该模型上存在的问题.此外,还介绍了纳米晶软磁材料的制备方法,并在最后对纳米晶软磁材料的应用及发展趋势作了展望.     

FeNHf软磁薄膜中磁各向异性对太赫兹波调控的研究

本文制备了具有磁各向异性的纳米FeNHf软磁薄膜,表征了FeNHf薄膜的微结构、磁性能、微波磁动力学行为和磁各向异性对太赫兹波传输特性的影响.FeNHf薄膜的难轴方向具有410的磁导率,易轴方向没有磁导率信号,磁各向异性场为2537.65 A/m.FeNHf薄膜在1.04 THz时出现了共振吸收峰,当调控磁化强度方向分...     

Microstructure and mechanical properties of Mg-Al-Zn alloy under a low-voltage pulsed magnetic field

Effect of a low-voltage pulsed magnetic field on the solidified microstructure and mechanical properties of Mg-Al-Zn alloy has been investigated. When the low-voltage pulsed magnetic field is applied during solidification, the as-cast microstructure is significantly refined and α-Mg is modified from developed dendrite to fine rosette. This morphology modification is caused by the accumulation of Joule heat on the dendrite tip. The yield strength is improved with the application of the low-voltage pulsed magnetic field under normal casting and semi-continuous casting conditions. The ultimate tensile strength is decreased slightly under normal casting condition due to the occurrence of plenty of shrinkage under the low-voltage pulsed magnetic field. The shrinkages are removed and the yield strength and ultimate tensile strength are increased under semi-continuous casting condition with low-voltage pulsed magnetic field.     

深过冷Fe82B17Si1合金的凝固组织与软磁性能

采用扫描电镜、X射线衍射仪等分析方法,系统研究了凝固组织对深过冷Fe82 B17 Si1合金软磁性能的影响.结果表明:该合金的最佳软磁性能位于Fe2B相完全粒化的超细球状非规则共晶组织区,通过减小该组织中Fe2B相尺度可进一步改善其软磁性能;该合金的磁损耗机制与常规软磁材料不同,材料中存在较大的剩余损耗,其磁损耗大幅度降低的Fe2B相临界尺寸为0.5μm左右.     

Impact of B alloying on ductility and phase transition in the Ni-Mn-based magnetic shape memory alloys: Insights from first-principles calculation

Brittleness is a bottleneck hindering the applications of fruitful functional properties of Ni-Mn-based multiferroic alloys.Recently,experimental studies on B alloying shed new light on this issue.However,the knowledge related to B alloying is limited until now.More importantly,the mechanism of the improved ductility,which is intrinsically related to the chemical bond that is difficult to reveal by routine experiments,is still unclear.In this context,by first-principles calculations,the impact and the correlated mechanism of B alloying were systemically studied by investigating four alloying systems,i.e.,(Ni2-xBx)MnGa,Ni2(Mn1-xBx)Ga,Ni2Mn(Ga1-xBx) and (Ni2MnGa)1-xBx.Results show that B prefers the direct occupation manner when it replaces Ni,Mn and Ga.For interstitial doping,B tends to locate at octahedral rather than tetrahedral interstice.Calculations show that the replacement of B for Ga can effectively improve (reduce) the inherent ductility (inherent strength) due to the weaker covalent strength of Ni(Mn)-B compared with Ni(Mn)-Ga.In contrast,B staying at octahedral interstice will lead to the formation of new chemical bonds between Ni(Mn) and B,bringing about a significantly improved strength and a greatly reduced ductility.Upon the substitutions for Ni and Mn,they affect both the inherent ductility and strength insignificantly.For phase transition,the replacement of B for Ga tends to destabilize the austenite,which can be understood in the picture of the band Jahn-Teller effect.Besides,the substitution for Ga would not lead to an obvious reduction of magnetization.     

纳米晶的形成对FeCSiBPCu非晶合金软磁性能的影响

研究了Fe76-xC7.0Si3.3B5.0P8.7Cux(x=0、0.3%或0.7%(原子分数))非晶合金中Cu的添加及纳米晶的形成对其软磁性能的影响,对合金的微观结构进行了X射线衍射实验和高分辨透射电镜观察,对合金的热稳定性和晶化激活能进行了测量和分析。结果表明,该合金退火之后的饱和磁化强度与合金中α-Fe纳米晶粒的密度和大小密切相关。Cu的添加可以影响合金的非晶形成能力、热稳定性和晶化激活能,添加少量的Cu(少于0.3%(原子分数))可以有效地提高合金的非晶形成能力,抑制退火过程中α-Fe纳米晶粒的析出,增强合金的热稳定性,而当Cu的添加量达到0.7%(原子分数)时可以降低合金的晶化激活能,促进α-Fe纳米晶粒的形核,提高α-Fe纳米晶粒的密度,使合金的饱和磁化强度达到1.79T。     

Phase transformations in sputtered Ni-Mn-Ga magnetic shape memory alloy thin films

Ni-Mn-Ga magnetic shape memory alloy films have been prepared by the DC magnetron sputtering technique. As-deposited films show a quasi-amorphous structure that crystallizes at ~ 500 K. Crystallization study using Kissinger's analysis reveals a relatively low activation energy indicating partial crystallinity in the films. In situ X-ray diffraction studies show reversible martensite phase transformations, and phase segregation to non-transforming L1₂ precipitates at higher temperatures. It was observed that the phase segregation can be suppressed by low temperature heat treatment.     

Strengthening via deformation twinning in a nickel alloy

Nanograins and nanotwins are produced in specimens using one processing technique to allow direct comparison in their nanohardnesses. It is shown that the hardness of nanotwins can be close to the lower end of the hardness of nanograins. The resistance of nanotwins to dislocation movement is explained based on elastic interactions between the incident 60° dislocation and the product dislocations. The latter includes one Shockley partial at the twin boundary and one 60° dislocation in the twinned region. The analysis indicates that a resolved shear stress of at least 1.24 GPa is required for a 60° dislocation to pass across a twin boundary in the nickel alloy investigated. It is this high level of the required shear stress coupled with a limited number of dislocations that can be present between two adjacent twin boundaries that provides nanotwins with high resistance to dislocation movement. The model proposed is corroborated by the detailed analysis of high-resolution transmission electron microscopy.     

高性能软磁合金的研究进展EI北大核心CSCD

软磁材料是一种极为重要且应用十分广泛的能源材料,近年来,随着磁性元件的日益高频化和小型化,以及节能环保的号召,开发和研究高性能软磁材料具有重要意义。本工作概述了软磁合金的发展历史,重点归纳出各类软磁合金(包括传统软磁合金、非晶/纳米晶软磁合金、高熵软磁合金)的成分、微观组织、磁性能以及应用范围,并总结出不同软磁合金的优、缺点;指出典型合金的微观组织对合金软磁性能(尤其矫顽力)具有关键性的主导作用,进而探讨了影响软磁合金矫顽力的因素及其微观机制,发现控制晶粒尺寸(或纳米粒子尺寸)是获得低矫顽力的关键,并描述了矫顽力的微观影响机制在高熵软磁合金中的发展;最后,展望了高熵软磁合金因多主元混合的成分特性带来的组织多样化,更有利于实现对合金性能的调控,并有望作为新一代高温软磁体材料。