Fe73.5Cu1Nb3Si13.5B9非晶合金电脉冲处理与等温退火的比较

用直流高密度电脉总和可比等温退火处理Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金,并用ＸＲＤ,ＴＥＭ和穆斯堡尔谱方法进行了结构检测。结果表明,在电脉冲作用下,Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｐ９非晶合金在平均温度为４２０℃的条件下发生了纳米晶化,晶化度试样中无Ｆｅ－Ｂ相析出,无ＤＯ３型有序结构;晶化总量达３０．９％的无序ａ－Ｆｅ（Ｓｉ）相的平均尺寸为８～９ｎｍ,按二项式分布计算ａ－Ｆｅ（Ｓ     

脉冲电流处理对Fe73.5Cu1Nb3Si13.5B9合金薄带GMI效应的影响

本文研究了脉冲电流处理对Fe73.5Cu1Nb3Si13.5B9合金薄带巨磁阻抗效应和脆性的影响,并与等温退火样品的巨磁阻抗效应和脆性进行对比.结果表明,经过应力脉冲电流处理后的样品,其阻抗变化率和灵敏度都显著高于无应力脉冲处理后的样品.淬态样品在9.34MPa拉应力下,经电流密度为930A/mm2的脉冲电流处理后,阻抗变化率可达到220%,灵敏度达到0.35%/A·m-1.用应力脉冲电流处理不仅可以显著提高巨磁阻抗效应,而且可以有效抑制样品长时间的等温退火带来的脆性问题.     

Fe73.5Cu1Nb3Si13.5B9非晶合金的晶化动力学

用差热分析（ＤＴＡ）结合Ｘ射线衍射（ＸＲＤ）,研究了Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金的晶化动力学。结果表明：温度在０～７００℃范围内,该合金的晶化相为α－Ｆｅ和Ｆｅ２Ｂ;α－Ｆｅ相晶化表观激活能为４５２．３９ＫＪ／ｍｏｌ,Ｆｅ２Ｂ相的晶化表观激活能３９５．２３ＫＪ／ｍｏｌ;两相在晶化初期激活能最小,随晶化量Ｘｃ的增加而迅速境大,在α－Ｆｅ的体积分类为３０％～８０％,Ｆｅ２Ｂ的体积分     

Fe73.5Cu1Nb3Si13.5B9软磁合金晶化处理

利用综合热分析仪测量了Fe73.5Cu1Nb3Si13.5B9晶化处理的焓变和晶化温度,并制定了不同的晶化退火工艺,利用振动样品磁强计自动测量仪对晶化处理后的试样进行了磁性能测定.研究结果表明,Fe73.5Cu1Nb3Si13.5B9软磁合金从250 ℃开始加热,经过370 ℃、470 ℃二次预热处理,在560 ℃保温1 h后,炉冷到250 ℃出炉冷却,可获得较高的软磁性能.     

Fe73.5Cu1Nb3Si13.5B9纳米晶的微结构

本文分别用ＪＥＯＬ－２０００ＦＸ分析电镜和ＪＥＯＬ－２０００ＥＸⅡ高分辨电镜研究了经磁场热处理的Ｆｅ７３．５Ｃｕ１Ｎｂ８Ｓｉ１３．５Ｂ９纳米晶中Ｆｅ（Ｓｉ）固溶体晶粒的大小、形状、晶粒间的接触及取向关系，重元素的偏聚和非晶基体的有序性等微观结构。     

机械合金化对Fe73.5Cu1Nb3Si13.5B9纳米晶合金结构的影响

研究Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９纳米晶合金在机械合金化过程中的结构的变化，发现将已经形成纳米晶的合金带经过短时间的机械球磨以后可以使它变非晶态粉末，若延长球磨时间可使非晶粉末再出晶化，并具有更步的晶粒。若将以非晶态粉末再进行退火可形成晶粒更微小的纳米晶。     

W、Nb对Fe76.5Cu1Si13.5B9非晶合金晶化行为的影响

用热分析法结合ＸＲＤ、ＴＥＭ研究了添加元素Ｗ、Ｎｂ对Ｆｅ７６．５Ｃｕ１Ｓｉ１３．５Ｂ９非晶合金晶化行为的影响。结果表明,Ｗ或Ｎｂ的加入都降低了Ｆｅ－Ｃｕ－Ｓｉ－Ｂ非晶合金反应的Ａｖｒａｍｉ指数ｎ;并且添加元素Ｎｂ更有利于该合金获得较小的ａ－Ｆｅ（Ｓｉ）晶粒。     

脉冲电流退火对Fe73.5Cu1Nb3Si13.5B9合金薄带巨应力阻抗效应的影响

研究了脉冲电流退火工艺对非晶Fe73.5Cu1Nb3Si13.5B9合金薄带巨应力阻抗（GSI）效应的影响。结果表明，在外加100MPa拉应力下对非晶合金进行脉冲电流退火后，巨应力阻抗效应显著提高，并且△Z／Z最大值随退火电流密度的增加而增加，当退火电流密度为930A／mm^2时，阻抗的最大相对变化达到350％。     

纳米晶软磁合金Fe73／5Cu1Nb3Si13.5B9淬态脆化机制研究

本文采用正电子湮没、居里点与内耗等方法对纳米晶磁合金Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９淬态脆化机制进行系统研究。研究结果表明ＦｅＣｕＮｂＳｉＢ淬态脆化是由于发生／构弛豫造成,且其结构弛豫峰温度比常用Ｆｅ－Ｂ－Ｓｉ非晶低得我,说明Ｆｅ－Ｂ－Ｓｉ非晶低得多,说明ＦｅＣｕＮｂＳｉＢ比常用Ｆｅ－Ｂ－Ｓｉ非晶易产生由结构弛豫造成的淬态脆化。     

非晶合金条带Fe73.5Cu1Nb3Si13.5B9的晶化动力学研究

采用差式扫描量热方法进行热分析实验,研究不同加热速率下非晶合金条带Fe73.5Cu1Nb3Si13.5B9的晶化动力学特性.DSC曲线的晶化温度和晶化峰值温度随着加热速率的增高而向高温方向迁移,说明合金的晶化过程表现出明显的动力学特性.建立基辛格模型,拟合动力学模型函数对结晶率的实验曲线,可以获得动力学参数值,得出晶化激活能的数值为2.89 eV.研究表明:对于Fe73.5 Cu1Nb3Si13.5B9合金,采用经验的双参数Sestak-Berggre模型能更加定量描述其晶化过程,而Johnson-Mehl-Avrami模型适宜在较低加热速率下描述.     

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。     

Fe73.5CulNb3Si13.5B9非晶合金的晶化动力学

用差热分析(DTA)结合X射线衍射(XRD),研究了Fe73.5Cu1Nb3 Si13.5B9非晶合金的晶化动力学.结果表明:温度在0～700℃范围内,该合金的晶化相为α-Fe和Fe2B;α-Fe相晶化表观激活能为452.39 kJ/mol,Fe2B相的晶化表观激活能395.23 kJ/mol;两相在晶化初期激活能最小,随晶化量Xc的增加而迅速增大,在a-Fe的体积分数为30%～80%,Fe2B的体积分数为40%～80%时,呈现极大值.     

退火工艺对Fe73.5Cu1Nb3Si13.5B9纳米晶带材耐腐蚀性能的影响

采用电化学方法研究了退火工艺对Fe73.5Cu1Nb3Si13.5B9纳米晶带材耐腐蚀性能的影响.用差热分析仪分析了该纳米晶带材的晶化过程,利用X射线衍射仪对经不同温度退火后的非晶带材的晶态结构进行了分析,并用恒电位法测试了样品在3.5%NaCl溶液中的耐腐蚀性能.结果表明,在3.5%NaCl溶液中,经过不同温度退火后的Fe73.5Cu1Nb3Si13.5B9纳米晶带材的耐腐蚀性能随退火温度的升高呈先增加后降低的趋势,其中530 ℃退火后的样品具有最好的耐蚀性.     

Effects of annealing condition and Al content on novel Fe73.5Si13.5B9Cu1Nb3-xAlx alloys

The annealing condition,Al content,and field amplitude dependences of the complex permeability for Nb-poor Finemet type alloys,Fe73.5Si13.5B9Cu1Nb3-xAlx (x=0,0.5,1.5,2.0,and 3.0),were investigated using an impedance analyzer and X-ray diffraction.The results show that different Al contents lead to different optimum annealing conditions,and the Al content exerts a distinct effect on microstructure thus resulting in a variety of real permeability value.For the samples annealed at 793 K for 0.5 h,the real permeability increases with an increase in Al content when the Al content is below 2.0 at.%; as for those annealed at 793 K for 1 h and at 813 K for 0.5 h,an overall increase in real permeability can be obtained compared to those annealed at 793 K for 0.5 h.The permeability under different field amplitudes is also studied and it is found that the relaxation frequency in the lower frequency region tends to moving toward a higher frequency with an increase in field amplitude.All these might be because of the role of Nb in the annealing process and the solubility of Al in the amorphous matrix and nanocrystallized crystallites.     

Cu clustering and Si partitioning in the early crystallization stage of an Fe73.5Si13.5B9Nb3Cu1 amorphous alloy

Solute clustering and partitioning behavior in the early crystallization stage of an Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous alloy have been studied by employing a three-dimensional atom probe (3DAP) and a high resolution electron microscope (HREM). Results from the 3DAP have clearly shown that Cu atom clusters are present in the amorphous state after annealing below the crystallization temperature. The density of these clusters is in the order of 10²⁴/m³, which is comparable to that of the α-Fe grains in the optimum nanocrystalline microstructure. In the early stage of primary crystallization, Cu clusters are in direct contact with the α-Fe nanocrystals, suggesting that the α-Fe primary particles are heterogeneously nucleated at the site of Cu clusters. In the early stage of crystallization, the concentration of Si is lower in the primary crystal than in the amorphous matrix phase, unlike in the late stage of the primary crystallization, where Si partitions into the α-Fe phase with a composition of approximately 20 at.%.