DT4E电磁纯铁真空退火磁性能不合格的分析和改进

某DT4E电磁纯铁零件真空退火后存在矫顽力超出设计要求的问题。针对此问题,对DT4E电磁纯铁进行了860～1150℃×4 h真空退火处理,研究了退火温度、磁性能测试试环尺寸以及原材料中杂质成分对其磁性能的影响。结果表明,随着退火温度的升高,磁感应强度B₂₅₀₀的变化呈“M”型,矫顽力H_c呈“V”型变化,最大磁导率μ_m与矫顽力H_c的变化趋势相反。最佳的真空退火温度为900℃,此时磁感应强度B₂₅₀₀为1.63 T,矫顽力H_c为25.19 A/m,最大磁导率μ_m为23.64 mH/m,满足设计要求,且磁环试件的规格尺寸对DT4E电磁纯铁磁性能的测量结果没有明显影响。原材料中杂质元素的含量对磁性能影响较大,当C含量较高时,磁导率下降,矫顽力升高,容易导致磁性能不合格。     

铁基纳米软磁合金的制备

介绍机械合金化方法制备纳米软磁合金的试验中,不同的球磨时间与晶粒尺寸之间的变化关系,并分析了晶粒尺寸,镍、钼等元素含量对磁导率、矫顽力、单位质量功耗等软磁性能的影响,认为在铁基纳米软磁合金中适量加入钼有利于改善综合软磁性能。     

粉末注射成形Fe-50%Ni软磁合金

Fe-50%Ni合金是一种典型的高磁导率和低矫顽力的软磁材料,有着广阔的应用前景.本次实验以羰基铁粉和羰基镍粉为原料粉末,采用注射成形方法制取Fe-50%Ni软磁合金,研究了高能球磨制备粉末对注射成形工艺以及材料性能的影响.研究结果表明与未经过高能球磨的混合粉末相比,高能球磨改变了原料粉末的粒度和粒度组成,提高了粉末的振实密度,进而提高了装载量.通过显微组织分析得知,高能球磨能使两种粉末发生塑性变形并冷焊合,形成了复合粉,促进了两种成分之间发生扩散和固态反应,同时还增加了粉末颗粒的能量,使颗粒表面活化,促进了烧结,提高了烧结材料的致密度.本实验最终获得了高性能的软磁合金材料磁导率41.27 mH/m,饱和磁感应强度1.498 T,矫顽力7.533 A/m.所得到的软磁材料性能优于相应传统粉末冶金方法获得的材料性能.     

热处理温度对Fe-Ni合金薄膜微结构及磁性的影响

采用直流电沉积法在硫酸盐-氯化物镀液中制备了Fe-44wt%Ni纳米晶合金薄膜.通过原子力显微镜(AFM)、X射线衍射(XRD)、透射电子显微镜(TEM)以及开路磁测量装置,对Fe-44wt%Ni合金薄膜镀态和退火态样品的微结构和磁性能进行测量.结果表明:退火温度升高能够降低薄膜内应力,使薄膜结晶均匀,但对薄膜晶粒尺寸和磁性能影响很大.Fe-44wt%Ni合金薄膜是由γ-(Fe,Ni)相和α-(Fe,Ni)相构成.在250℃真空退火处理1h后Fe-44wt%Ni合金薄膜的晶粒尺寸在20～30 nm之间,且具有良好的软磁性能,饱和磁感应强度BS为1.06T,矫顽力HC为40A/m.     

磁粉粒径对烧结Nd-Fe-B磁性能和初始磁导率的影响

采用粉末冶金法制备了名义成分为(Pr_(25)Nd_(75))_(25)Dy_6Al_(0.5)B_1Co_1Cu_(0.2)Fe_(bal)的烧结Nd-Fe-B磁体,并研究了不同粒径磁粉制备的烧结Nd-Fe-B磁体磁性能和初始磁化阶段最大磁导率的相应演变规律。结果表明,磁粉平均尺寸为3.0μm时对应的磁体的内禀矫顽力最大,磁粉平均尺寸为3.5μm时对应的磁体的剩磁最高。从磁体的微观结构观察和性能测试发现,磁粉粒径为3.0μm时,烧结磁体主相更加规则、均匀,提高了磁体的矫顽力。随着磁粉平均尺寸进一步减小,磁粉粒径为2.5μm时,富Nd相以氧化物形式发生了团聚,且分布不均匀,磁体晶界出现孔洞,去磁耦合效率下降,导致磁体矫顽力降低;磁体氧含量随着磁粉平均尺寸的减小而增大,磁体内杂质相增多,剩磁下降;增多的杂质相使得磁化初始阶段的最大磁导率降低。     

晶粒尺寸对无取向硅钢磁性能影响的主成分回归分析

采用电子背散射衍射技术测定50SW1300冷轧无取向硅钢中不同尺寸范围晶粒的含量,利用主成分回归分析法,综合研究不同尺寸范围晶粒的含量对无取向硅钢磁性能的影响。结果表明:通过主成分回归分析法能够从不同尺寸范围晶粒的含量的多个影响因素中获取主要的因素,定量研究它们对无取向硅钢磁性能的影响规律。分析表明,无取向硅钢的铁损与不同尺寸范围晶粒的含量之间存在着可靠的多元线性关系,在一定范围内,较大尺寸晶粒的含量越多,其对铁损优化的作用越明显;而无取向硅钢的磁感与不同尺寸范围晶粒的含量之间并无线性关系。     

机械合金化制备Al_(65)Fe_(25)Ni_(10)纳米合金粉的磁性研究

用机械合金化法制备A165Fe25Ni10纳米合金粉末.采用X射线衍射(XRD)、振动样品磁强计(VSM)研究了其结构和磁性随球磨时间的演变.结果表明:在球磨初期,粉末晶粒尺寸急剧减小,内应变迅速增大:球磨50 h后晶粒尺寸、内应变基本保持稳定.矫顽力(Hc)随球磨时间的增加先增大,球磨50 h后急剧减小.在晶粒尺寸较小时,矫顽力与晶粒尺寸的六次方成正比;晶粒尺寸较大时,矫顽力与晶粒尺寸成反比.     

退火温度和铬元素对电工钢组织和性能的影响

利用显微镜、磁性测量仪等手段对不同Cr含量的电工钢经不同温度退火后的组织和磁性能进行了研究。结果表明,添加Cr元素能有效细化电工钢的晶粒尺寸和提高其组织在退火过程中的稳定性。由于受到内应力和晶粒尺寸双重影响,随退火温度的升高材料的铁损先降低后升高,Fe-6.5wt%Si-1.0wt%Cr材料的较优退火温度为1000℃。     

热处理工艺对冷轧双相钢显微组织与磁性能的影响

主要研究水淬与过时效工艺对冷轧双相钢显微组织和磁性能的影响。建立水淬及过时效工艺参数与显微组织和磁特性参数的对应关系。结果表明,水淬双相钢主要由铁素体和马氏体组成,马氏体体积分数随保温温度和水淬温度的升高而增大;矫顽力与磁滞损耗随保温温度和水淬温度的升高而增大,而剩磁和最大磁导率呈下降趋势;过时效过程中,马氏体发生分解;矫顽力和磁滞损耗随过时效温度的升高而减小,剩磁和最大磁导率呈上升趋势。     

保温时间对1J79软磁合金磁性能影响的研究

采用真空电弧炉熔炼制备1J79软磁合金,研究了热处理保温时间对1J79软磁合金磁性能的影响.通过电子探针观察其杂质的含量及晶粒的长大情况;并采用振动样品磁强计测得合金的磁滞回线,分析其磁性能的变化.实验结果表明,随着保温时间的延长,合金的矫顽力Hc显著降低,饱和磁化强度显著提高.     

Powder injection molding of Fe-Ni soft magnetic alloys

With miniaturization and complication of the shape of electronic devices in recent years, powder injection molding (PIM) seems to be a suitable process for fabricating the higher performance soft magnetic components. In this paper, high quality Fe-50Ni soft magnetic alloy was fabricated by PIM with carbonyl iron and nickel, and the effect of sintering process on its microstructure and magnetic properties were investigated. The mechanical and magnetic properties can be obviously improved by increasing the sintering temperature or using the hydrogen atmosphere instead of high vacuum, which causes by the increase of grain size and the densification. At the optimum sintering conditions, the PIM Fe-50Ni soft magnetic alloy with high properties are obtained, whose relative density, tensile strength, Bm, Hc,μm are 97%, 465MPa,1.52T, 16.62 A·m-1 , 42.5 mH·m-1 , respectively.     

Enhanced sintering of an Fe-Ni-P coated composite powder prepared by electroless nickel plating

An Fe-8.2 % Ni-6.0 % P powder was prepared by electroless nickel plating on a carbonyl iron powder, where phosphorous appeared as a contaminant of the plating process. Because of the high phosphorous concentration, persistent liquid phase sintering was effective at temperatures higher than 1000 °C. The sintered microstructure was dramatically different from the conventional approaches, where a low concentration of phosphorous was added in the form of Fe₃P. Sintering the alloy at a temperature as low as 1050 °C for 30 min yielded a sintered density of 98.6% theoretical and rounded grains having an average grain size of 53 μm. The rounded grains were surrounded by a large volume fraction of intergranular (Fe,Ni)₃P phase, arising from the high phosphorous concentration, which slightly deteriorated the magnetic saturation but significantly increased the electrical resistivity of the alloy. Generally speaking, the magnetic saturation of the sintered alloy was improved with respect to the iron-phosphorus, iron-nickel, or iron-silicon alloys fabricated by powder processing.     

The effect of heat treatment on the structure and magnetic properties of mechanically alloyed Fe-45%Ni nanostructured powders

Magnetic iron-nickel alloys generally called permalloys are of great interest due to their magnetic properties. Fe-45%Ni alloy is one of the major iron-nickel compositions, well-known for high flux density, low coercivity and their responsiveness to the magnetic annealing. In this study, nanocrystalline Fe-45%Ni alloy powders were prepared by mechanical alloying process using a planetary high-energy ball mill under an argon atmosphere. The synthesized powders were heat treated at different temperatures using a vacuum furnace. The structural properties of the as-milled and the post-heat treated powders were studied by means of X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). The magnetic measurements on the powders were carried out using a vibrating sample magnetometer (VSM). The results showed that the lattice strain decreases and the crystallite size increases with annealing temperature. It was also found that the variation of coercivity is dominated by the removal of residual stress at low annealing temperatures, whereas the value of coercivity depends on the crystallite size at higher annealing temperatures.     

Fe-32%Ni合金超细晶粒奥氏体的马氏体相变微观结构研究

通过多轴锻造的方法实现了Fe-32%Ni合金奥氏体晶粒超细化,并进行深冷处理使之发生马氏体相变.采用透射电镜(TEM)观察了超细晶粒Fe-32%Ni合金奥氏体相变后马氏体的微观结构.结果表明,超细晶粒奥氏体相变后的马氏体片变得不再完整,部分马氏体片边缘变得弯曲,部分马氏体发生了中脊断裂现象;观察马氏体片的亚结构表明,有些马氏体片的亚结构是孪晶与高密度位错共存,有些马氏体片的亚结构转变为高密度位错.分析认为强变形马氏体特殊亚结构的生成是由于奥氏体组织细化大大提高了母相强度,加大了相变切变阻力和强变形奥氏体母相中大量位错的引入破坏了母相晶格原子排列的空间规律性等原因造成的.     

直流磁场对Fe-Cr-Mo合金阻尼性能的影响

利用倒扭摆内耗仪研究了外加直流磁场对Fe-16Cr-2.5Mo合金阻尼性能的影响，采用水基磁流体观察分析了磁畴结构的变化。实验表明，在直流磁场作用下，Fe-16Cr-2.5Mo合金阻尼性能随磁场强度的增大而增大，在0．08mT磁场强度下，合金的阻尼性能达到最大，之后随磁场强度的增大又降低到最低值。施加外磁场后，磁畴显得宽大和均匀，并且发生了明显壁移。研究表明。直流磁场对磁畴结构的影响是导致合金阻尼变化的重要原因。     

New Fe-based soft magnetic amorphous alloys with high saturation magnetization and good corrosion resistance for dust core application

Fe-rich amorphous dust core alloys with minor-addition of Mo and/or Cr were synthesized because of the industrial request of mass production of high efficient low core loss Fe-based dust cores. It was found that the present Fe-(Cr, Mo)-P-B-Si-(C) amorphous alloy ribbons exhibit good soft magnetic properties of above 1.5 T for saturation magnetization, below 10 A/m for coercivity and rather good corrosion resistance in 3%NaCl aqueous solution. Besides, the amorphous alloy ribbons exhibit good bending ductility in as-spun and optimally annealed states. It is noticed that these characteristics are much superior to those for commercial Fe-Cr-Nb-P-B-Si soft magnetic dust core alloy (SENNTIX). In addition, the annealing treatment was noticed to cause the improvement of corrosion resistance without detriment to bending ductility. The new Fe-based soft magnetic alloys with good combined characteristics are expected to be used as the basic material as high-efficient soft magnetic dust cores in a high frequency range.     

Effects of phosphorus addition on the magnetic properties of sintered Fe-50 wt.% Ni alloys

Phosphorus was added to Fe-50 wt.% Ni in the form of a coated composite powder via an electroless plating process. Addition of phosphorus to Fe-50 wt.% Ni facilitated increases in density and grain size, both of which were beneficial to magnetic performance. Because of the homogeneous distribution of phosphorus in the powder, the optimal phosphorus addition was much lower than for those using Fe₃P as the phosphorus precursor. The optimal phosphorus addition was close to its maximum solubility in Fe-50 wt.% Ni (about 0.5 wt.%), above which precipitation of excessive phosphorus in the form of iron nickel phosphide, (Fe,Ni)₃P, effectively degraded the magnetic properties of Fe-50 wt.% Ni. Without the addition of phosphorus, good magnetic properties could be achieved only when the sintering temperature was high enough (>1200 °C) to result in a high sintered density and large grains in the sintered structure.     

80%Fe-10%Co-10%Ni合金粉的制备

采用共沉淀方法制备了80%Fe-10%Co-10%Ni前驱体粉,考察了搅拌强度、滴定终点溶液的pH值、反应温度和反应时间对前驱体粉回收率的影响,并通过三因素三水平的正交实验,优化了工艺条件。采用氢还原法制备了80%Fe-10%Co-10%Ni合金粉,考察了还原温度对转化率和平均粒度的影响。实验结果表明:制备前驱体粉的工艺条件为搅拌强度2000r/min、pH值为11、反应温度20℃、反应时间35min;氢还原法制备80%Fe-10%Co-10%Ni合金粉的工艺条件为:反应温度700℃、反应时间30min;还原温度越高,反应速度越快,产品粒度越大。     

Finished surface morphology,microstructure and magnetic properties of selective laser melted Fe-50wt% Ni permalloy

This work focuses on the structure and magnetic properties of Fe-50wt% Ni permalloy manufactured from the pre-alloyed powder by selective laser melting (SLM). The selective laser melted (SLMed) alloys were characterized by a 3D profilometer,optical microscope, scanning electron microscope, X-ray diffraction, etc. The effects of the volume energy density of laser(LVED) on structure, and magnetic properties with coercivity ( H _c ), remanence ( B _r ), and power losses ( P     

软磁合金的磁特性

通过对软磁合金在直流与交流磁化条件下的磁性能参数的测量、分析、比较,研讨了高磁导率合金的直流与交流磁特性之间的差异,找到了影响铁芯磁性能的原因。对如何提高软磁合金产品质量作了一些具有应用价值的探讨,以供软磁材料的研制、开发及应用时作参考。