HIGH-TEMPERATURE AC MAGNETIC PROPERTIES OF NANOCRYSTALLINE FINEMET ALLOYS WITH Co ADDITION

High-temperature AC magnetic properties for (Fe0.5Co0.5)73.5Cu1Nb3Si13.5B9 alloy annealed at various temperatures have been investigated using an impedance analyzer. Annealing temperature Ta has obvious effects on high-temperature AC magnetic properties of the alloy. The Hopkinson peak appears only in the amorphous alloy when Ta ≤ 703K. As Ta increases above 733K, the real part of the complex initial permeability μi' descends gradually, μi' decreases more slowly with temperature in the high temperature range. The high-temperature (about 750K) AC initial permeability for the alloy annealed at Ta=763K has been found to maintain a stable high value of 950 up to a frequency of ~ 1 × 105Hz. Partial substitution of Co for Fe in the Fe73.5Cu1Nb3Si13.5B9 alloy leads to an increase of around 110K of the Curie temperature of the amorphous phase, much higher than Ge-containing Finemet alloy.     

NANOCRYSTALLINE STRUCTURE AND INITIAL PERMEABILITY OF ANNEALED Fe_（73．5）Cu_1W_3Si_（13．5）B_9 Alloy

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Fe基非晶及纳米晶合金的制备和电化学腐蚀行为

分别采用单辊甩带法和非晶晶化退火法制备出非晶及纳米晶合金Fe73.5Si13.5B9Nb3Cu1;利用DSC、XRD和TEM对该非晶合金的晶化行为进行了分析;并用电化学极化曲线的方法和电化学阻抗技术研究了该非晶合金经不同温度退火后在1mol/LHCl溶液里的电化学腐蚀行为。结果表明,该非晶合金的晶化过程出现2个阶段。当退火温度为500℃时,合金尚未晶化,仍保持非晶态;当温度达到550℃时,出现了晶化衍射峰,晶粒平均直径约13nm;当温度达到600℃时,晶粒平均直径约为15nm。经过退火得到的纳米晶合金的腐蚀电位大于未退火的非晶,且阳极电流密度变得更低,表明纳米晶状态时的耐腐蚀性能比非晶状态的更好。该非晶合金未退火、550℃退火和600℃退火时的EIS均由单一容抗弧构成,具有一时间常数;且随着退火温度升高,电化学反应电荷转移电阻在增大。     

Magnetic properties of nanocrystalline Finemet alloys with Co addition

This report focuses on ac magnetic properties of (Fe_0.5Co_0.5)_73.5Cu₁Nb₃Si_13.5B₉ alloy in the high temperature. The effects of replacing 50% Fe by Co in Fe_73.5Cu₁Nb₃Si_13.5B₉ alloy on the static magnetic properties have also been studied. Addition of Co leads to an increase around 110 K of the Curie temperature of the amorphous phase, much higher than Ge-containing Finemet alloy. The material has much better ac magnetic properties than Hitperm alloy. An excellent stability of initial permeability in high temperature (up to 650 K) and high frequency (up to 5 × 10⁵ Hz) can be observed with respect to the Co-free alloy.     

铁基非晶及纳米晶合金在NaOH溶液中的耐蚀性比较

冶炼制备了纳米晶Fe73.5Si13.5B9Nb3Cu1和非晶带材Fe78Si13B9。在电化学工作站上测试了两种合金在不同浓度的NaOH碱溶液里的极化曲线。随着NaOH溶液浓度的不同,非晶Fe78Si13B9和纳米晶Fe73.5Si13.5B9Nb3Cu1合金极化曲线具有相似的变化规律,且纳米晶合金比非晶合金的腐蚀电位要高,耐腐蚀性要好。     

Effects of Mo substituted Nb on magnetic properties of Finemet alloy

Different Mo contents have been added into traditional Finemet alloy to form Fe73.5Cu1Nb3-x MoxSil3B9.5( x = 0 - 3) alloys. The change in DC and AC magnetic properties with Mo for Nb substimtlon was investigated. The results show that, with adding Mo, although the DC relative permeability decreases and the coercive force increases slightly,the saturation flux density Bs can be increased, and the core loss of the alloy can be decreased. The AC permeability of samples contained Mo is higher than that of alloy without Mo content. Fe73.sCu1Nb1Mo2Si13B9.5 alloy has the highest saturation flux density Bs. Fe73.sCu1Nb2Mo1Si13B9.5 alloy has the best frequency dependence on the AC permeability and core loss.     

Fe基非晶合金的晶化及其在NaCl溶液中的电化学腐蚀行为

采用单辊甩带法制备出完全非晶态的Fe_(78)Si_(13)B_9和Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1薄带,并利用非晶晶化退火法制备非晶和纳米晶双相合金Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1薄带.利用X射线衍射仪和示差扫描量热计对该非晶薄带的非晶特性及其晶化过程进行研究,并用电化学极化曲线的方法和电化学阻抗技术对比研究非晶Fe_(78)Si_(13)B_9和双相合金Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1在1 mol/L NaCl溶液里的电化学腐蚀行为,用SEM对极化测试后的试样形貌进行观察;同时还研究不同的热处理温度对材料的结构及在1 mol/L NaCl溶液里耐腐蚀性能的影响.结果表明:该非晶薄带的晶化过程分为两步;双相合金比非晶合金的耐腐蚀性要好;随着热处理温度升高,非晶合金和双相合金的耐腐蚀性能都得到提高.     

Fe73.5Cu1Nb3-xTixSi13.5B9 (x=0, 1, 2, 3)合金粉的结构与磁性

将Fe73.5Cu1Nb3-xTixSi13.5B9(x=0,1,2,3)合金快淬带进行高能球磨制成粉末样品,在550℃真空退火1h,研究了磁粉的相结构及磁性。结果表明,随球磨时间延长,不添加Ti的Fe73.5Cu1Nb3Si13.5B9合金中析出晶化相的晶格常数增大。添加Ti的Fe73.5Cu1Nb3-xTixSi13.5B9(x=0,1,2,3)合金在球磨60h后再退火,可以得到单一α-Fe(Si)软磁相,且随Ti含量增大,析出晶化相的晶格常数减小,饱和磁化强度增大、矫顽力降低。     

测量非晶合金激活能的新方法

介绍了一种测量非晶晶化激活能的新方法－MTGA法。分别用DSC和MTGA研究了Fe73.5Cu1Nb3Si13.5B9非晶合金的晶化动力学。结果表明,MTGA法不但比DSC法能更加详细反映出晶化动力学和相变的过程,而且用DSC和MTGA测量的α－Fe(Si)相的晶化激活能基本一致。     

预退火对Fe73.5Cu1Mo3Si13.5B9非晶合金的晶化及磁性的影响

本文研究了预退火温度和时间对Ｆｅ(７３．５)Ｃｕ１Ｍｏ３Ｓｉ(１３．５)Ｂ９非晶合金在最后退火过程中发生的 晶化及软磁性能的影响。结果表明：在较低温度下预退火能有效地控制合金的晶化过程,降低了最 后退火时所放出的晶化潜热。该合金在４５０℃进行１ｈ预退火发生部分晶化,释放约３２％的晶化 潜热,再经５１０℃保温１ｈ最后退火其磁性能与制备态样品经５１０℃退火后的磁性能相比,最大磁 导率ｍ显著提高,矫顽力Ｈｃ明显下降,Ｂｓ和Ｂｒ无明显变化。