矩形脉冲电流退火与激励电流对Co基非晶带巨磁阻抗效应的影响

利用矩形脉冲电流对Co_(66.3)Fe_(3.7)Si_(12)B_(18)非晶带进行退火处理,研究了退火电流密度对非晶带巨磁阻抗效应的影响,同时研究了激励电流频率对退火处理后的非晶带巨磁阻抗效应的影响。结果表明,该非晶带的特征频率为1.4 MHz。最大巨磁阻抗所对应的磁场随激励电流频率的增加逐渐向高磁场方向移动。     

退火工艺对Co71．8Fe4．9Nb0．8Si7．5815非晶薄带巨磁阻抗效应的影响

采用四端法研究了退火处理T艺对Co71.8Fe4.9Nb0.8Si7.5B15非晶薄带巨磁阻抗效应的影响.结果表明,Co71.8Fe4.9Nb0.8Si7.5B15非晶薄带试样经350 ℃保温60 min退火处理后,样品的内应力得到有效释放,大大改善了样品的软磁特性,得到了最大的巨磁阻抗效应(GMI).在8 MHz的交变电流频率下,得到了24%的最大磁阻抗比.XRD分析表明,样品发生晶化后将降低巨磁阻抗(GMI)效应.     

磁场退火对CoFeNiNbSiB薄带巨磁阻抗的影响

本文研究了磁场退火对CoFeNiNbSiB非晶薄带巨磁阻抗（GMI）效应的影响，样品在不同条件下进行了退火热处理，结果表明，在300℃下经横向磁场退火处理后获得了最佳的软磁特性，从而得到了最大的GMI效应，在800KHz的交变电流频率下，得到了236%的最大磁阻抗比，在低场下，材料的磁阻抗磁场灵敏度达到1152%/mT。     

非晶FeCuNbSiB带材压磁性能的特点

采用点压方式研究非晶FeCuNbSiB带材的压磁性能,利用X-Ray测试带材结构,用DSC确定相转变,用4294A阻抗分析仪测试阻抗.结果表明:非晶FeCuNbSiB带材具有优越的压磁性能和压磁稳定性,压磁敏感性可以通过调整退火工艺来实现.当退火温度为300℃,保温时间为1 h时非晶FeCuNbSiB带材的压磁性能最佳,在压力为1.42 MPa,频率为100MHz时,|△Z|可达2.88Ω.     

Fe_(72.5)Cu_1Nb_2V_2Si_(13.5)B_9纳米晶薄带的巨磁阻抗效应

Fe72.5Cu1Nb2V2Si13.5B9非晶薄带经晶化退火处理,随退火温度增加,析出纳米晶bccα-Fe(Si)相,当超过550℃,薄带在析出纳米晶bccα-Fe(Si)的同时,还析出硬磁性的Fe2B相。Fe72.5Cu1Nb2V2Si13.5B9纳米晶薄带具有巨磁阻抗(GMI)效应,其效应强度灵敏依赖于退火温度,当退火温度为550℃、退火时间为30 min时,bccα-Fe(Si)平均晶粒尺寸约为16nm,其巨磁阻抗存在最大值。巨磁阻抗效应还强烈依赖于频率。对于550℃退火30min的Fe72.5Cu1Nb2V2Si13.5B9纳米晶薄带,其在50kHz下,ΔX/X(H=7 162A/m)可达到-500%,3 MHz下,ΔR/R(H=7 162A/m)约为-150%。700kHz下,GMI效应值有最大值,ΔZ/Z(H=7 162A/m)约为-121%。     

Co-Fe-Si-B非晶丝的巨磁阻抗效应研究

通过傅立叶分析模型研究了CoFeSiB非晶丝的GMI效应，将得出的阻抗计算结果与实验比较，发现该模型较符合实验规律。同时计算了非晶丝半径、饱和磁化强度以及电阻率对GMI效应的影响，结果表明增大非晶丝半径，增大饱和磁化强度以及降低电阻率都能使非晶丝的巨磁阻抗效应增大。     

Fe88Zr7B4Co1软磁纳米晶薄带的巨磁阻抗效应

利用熔旋快淬技术在铜辊速度为40 m/s的条件下制备了Fe88Zr7B4Co1薄带,分别经550、600、650、700、725、750℃退火处理30 min,形成纳米晶薄带.研究了退火温度、外磁场和驱动电流频率对巨磁阻抗效应的影响.发现存在一个最佳退火温度650℃.其bcc α-Fe相的晶粒尺寸为11.3 nm,在此温度下制备的Fe88 Zr7 B4 Co1纳米晶薄带具有最强的巨磁阻抗效应:在H=90 Oe下,频率约为1 MHz时Fe88Zr7B4Co1纳米晶薄带的磁阻抗△Z/Z0达到-52%.Fe88Zr7B4Co1纳米晶薄带具有比未掺杂的Fe88Zr7B4更强的巨磁阻抗效应.     

低频脉冲电流退火对CoFeSiB非晶薄带巨磁阻抗效应的影响

研究了经不同低频脉冲电流密度退火的Co66.3Fe3．7Si12B18非晶薄带的巨磁阻抗（GMI）效应。结果表明，在低频脉冲电流下，巨磁阻抗效应的大小与退火电流密度密切相关。非晶带的GMI变化率△Z／Z先随退火电流密度的增加而增强，当电流密度为104A／mm^2时，△Z／Z达到最大值53．8％，此后随电流密度增大，GMI变化率开始减小。对脉冲电流退火影响巨磁阻抗效应的机制作了定性分析。并分析了由脉冲电流退火在材料内感生的横向各向异性场凤对GMI效应的影响，发现HK有利于提高GMI效应的峰值，但同时存在一个临界值，当超过这个值时，GMI效应的峰值减弱。     

电塑性冷拔对水淬非晶丝GMI性能的影响

电塑性冷拔是基于金属材料电塑性效应的一种加工工艺,在非晶丝材料后处理中引入电塑性冷拔工艺,对非晶丝材料的塑性变形、组织结构有显著影响。适当的脉冲电流不仅能显著改善非晶丝的加工性能及力学性能,还能减少非晶丝表面的缩孔、缩松,提高非晶丝材料的表面光洁度,改善非晶丝材料的巨磁阻抗(GMI)性能。     

FeSiB-La合金的非晶形成能力和磁阻抗效应

将稀土La元素掺杂Fe78Si9B13合金,采用单辊法制备了FeSiB-La非晶带材,再将非晶带材在不同温度下进行退火处理。用DSC和XRD分析了带材的非晶形成能力和晶化行为,用阻抗分析仪测试了非晶带材的磁阻抗效应。结果表明,掺杂稀土La元素可提高带材的非晶形成能力,延缓带材中Fe-Si、Fe-B晶化相的析出,增强带材的热稳定性;Fe Si B-La非晶带材的磁阻抗效应随测试频率的升高和磁场强度的增大而增大;随退火温度升高,非晶带材的磁阻抗效应呈先增大后减小的趋势。     

Effect of glass removal on the GMI effect of Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires

During the past several years, giant magneto-impedance effect (GMI) in amorphous wires has generated growing interest in the science community because of theirapplications in sensors. The giant magneto-impedance effect in Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires (AGCW) consists of strong changes in the high frequency impedance with a small DC magnetic field. When f =1 MHz, there is no GMI effect due to the fact that the magnetic penetration depth is higher than their radius. As the frequency increases, the GMI effect becomes important in both the glass-covered wire and the wire afterglass removal. Field dependence of the impedance has a similar behaviour to the AGCW ones, when a tensile stress is applied to the wire without glass cover.     

玻璃包覆钴基非晶细丝的巨磁阻抗研究

深入研究了玻璃包覆的成分为Ｆｅ６８．２５Ｃｏ４．５Ｓｉ１２．２５Ｂ１５,直径为２５ｕｍ的非晶细丝的巨磁阻抗效应。在频率为０．１～１２ＭＨｚ,磁场在０～５．２ｋＡ／ｍ的范围内测量了交流磁电阻、磁电抗、磁阻抗对频率及磁场的依赖关系。发现该细丝材料的巨磁阻抗ＧＭＩ（Ｚ）值在测量频率范围内随频率增大而增大。     

Effect of Cooling Rate in Heat Treatment on the Magnetic Properties of Amorphous Cobalt-Based Alloys of the AMAG Type

Results of a study of the effect of a wide range of cooling rates in thermal and thermomagnetic treatment on the magnetic properties (permeability, coercive force, and coefficient of squareness) of amorphous strips from magnetically soft cobalt-based alloy AMAG 176 of the Co – Fe – Ni – Si – B system are considered. Variation of these properties is discussed.     

Improvement of giant magneto impedance of Co-rich melt extraction wires by stress-current annealing

In order to improve the giant magneto impedance(GMI) of Co-rich wires for high sensitive sensor applications,Co68Fe4.5Si15B12.5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile stresses applied.And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz.It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments,because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy,which improved the circular permeability and GMI effect.Their impedance ratio △Z/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/(A/m) at 5 MHz,when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min.It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.     

铜模吸铸法制备的Fe74Al4Sn2P10Si4B4C2非晶合金圆棒及圆管块体

利用铜模吸铸法制备了直径1．0mm,1．5mm和2．0mm的Fe74Al4Sn2P10Si4B4C2块体非晶合金圆棒,利用振动样品磁强计测试了圆棒的磁性能,其饱和磁感应强度较高,矫顽力较低。利用铜模吸铸法制备了Ф5mm×庐7mm×15mm的Fe74Al4Sn2P10Si4B4C2块体非晶合金圆管,并测试了其DSC曲线,块体非晶合金圆管与块体非晶合金圆棒的热性质一致。Fe74Al4Sn2P10Si4B4C2块体非晶合金显示出优良的铸造性能。     

pH值对电沉积FeNi／Cu复合丝巨磁阻抗性能的影响

采用脉冲电沉积方法在φ90μm的Cu丝上制备出Fe20＋δNi80-8／Cu复合丝，并测试了巨磁阻抗（GMI）特性。实验表明：电镀液的pH值在1．48～3．1范围内变化，对于复合丝的镀层成分、厚度、表面质量及其巨磁阻抗（GMI）效应具有显著的影响。在pH为1．9～2．5时复合丝表面平整、缺陷少，在pH=2．03时获得了厚度为11μm、成分为Fe20．3Ni79．7的电镀沉积层。采用10mA的激发电流，频率f=29．6kHz时GMI效应达到631．5％，磁场的灵敏度在10kHz时达到560％／Oe，该频率远远低于CoFeSiB非晶丝材的频率。     

Fe73.5Cu1Nb3Si13.5B9非晶丝扭矩阻抗（TGI）效应的研究

本文研究了测量频率、焦耳退火处理及扭矩焦耳退火处理对Fe73.5Cu1Nb3Si13.5B9非晶丝TGI效应的影响。实验表明淬态Fe73.5Cu1Nb3Si13.5B9非晶丝TGI效应的最佳测量频率为7 MHz;对样品进行焦耳退火处理可以提高样品的阻抗变化率,测量频率为7 MHz时,焦耳退火处理的最佳电流密度为32 A/mm2,最大阻抗变化率达198%;扭矩焦耳退火处理后,样品TGI效应的非对称性随着预加扭矩的增大而增大,同时阻抗变化率峰值减小。     

镍基非晶态合金材料真空钎焊特性研究

研究了非晶态Ｎｉ（８０－ｘ）Ｃｒ１０Ｂ２．５Ｓｉ４，５Ｆｅ３Ｃｕｘ合金钎料真空钎焊１Ｃｒ１８Ｎｉ９Ｔｉ的钎焊特性，并对铜的影响进行了探讨。结果表明，非晶态合金钎料钎焊性能优于晶态合金钎料，铜的适量添加有利于提高钎焊接头的综合性能。     

Crystallization kinetics of （Ni0.75Fe0.25）78-xNbxSi10B12 （x = 0, 5） amorphous alloys

Amorphous ribbons of （Ni0.75Fe0.25）78-xNbxSi10B12 （x = 0, 5） were prepared by a single roller melt-spinning technique in air atmosphere. The crystallization kinetics of the alloys were investigated by means of continuous heating, and the activation energies of the alloys were calculated using Kissinger plot method and Ozawa plot method on the basis of differential thermal analysis data. The crystallization products were analyzed by X-ray diffraction. After the （Ni0.75Fe0.25）78Si10B12 amorphous alloy was annealed at the temperatures 715 and 745 K, a single phase of γ-（Fe, Ni） solid solution with grain sizes of about 10.3 and 18.5 nm, respectively, precipitates in the amorphous matrix. The crystallized phases are γ-（Fe, Ni） solid solution, Fe2Si, Ni2Si, and Fe3B after annealing at 765 K. The （Ni0.75Fe0.25）73NbsSi10 B12 amorphous alloy was annealed at 720, 750, and 800 K; and the crystallization phases, γ（Fe, Ni） solid solution, （Fe, Ni）23B6. Ni31Si12 and Nb2NiB0.16 form simultaneously.     

添加剂对低压烧结Zr50Al15Ni10Cu25非晶态粉末力学性能的影响

以商业纯元素粉末为原料,用机械合金化方法在低真空条件下合成了以非晶态为主的Zr50Al15Ni10Cu25粉末。研究了一定量的外界添加剂C、Si3N4和SiC对体系热稳定性和晶化行为的影响。混合粉末用手工预压成形,然后在氩气氛下进行低压烧结。利用X射线衍射（XRD）、扫描电镜（SEM）、差热分析（DSC）和电子拉伸实验机对粉末样和块状样进行了测试。结果表明,合适的外界添加剂可以提高体系的析晶活化能,增强体系的热稳定性。适量的Si3N4能促进Zr50Al15Ni10Cu25非晶粉末的低压烧结性能,即有助于提高样品的烧结致密度和样品的抗弯强度。