MSSBAUER STUDY ON MAGNETIC ANISOTROPY OF AMORPHOUS ALLOY Fe_(71)Ni_(10)B_(13)Si_4C_2

本文研究了Fe_(71)Ni_(10)B_(13)Si_4C_2非晶态合金在磁场退火时的反常磁各向异性变化。结果表明,在430℃磁场热处理时优先发生了表面晶化现象,导致垂直磁各向异性的反常增大。磁矩取向的择优性取决于压应力引起的和磁场热处理感生的两种磁各向异性。     

非晶态合金Fe_(71)Ni_(10)B_(13)Si_4C_2磁各向异性的Mssbauer谱研究

本文研究了Fe_(71)Ni_(10)B_(13)Si_4C_2非晶态合金在磁场退火时的反常磁各向异性变化。结果表明,在430℃磁场热处理时优先发生了表面晶化现象,导致垂直磁各向异性的反常增大。磁矩取向的择优性取决于压应力引起的和磁场热处理感生的两种磁各向异性。     

磁场退火对纳米晶合金软磁性能的影响

利用真空退火,将非晶合金纳米晶化,并通过XRD试验手段验证了其纳米晶结构,研究了磁场退火对纳米晶合金软磁性能的影响。研究表明,在外加磁场条件下,对Fe_(74.5)Cu_1Nb_2Si_(13.5)B_9、(Fe_(0.5)Co_(0.5))_(73.5)Cu_1Nb_3Si_(13.5)B_9和Ni_(25)(Fe_(0.5)Co_(0.5))_(48.5)Cu_1Nb_3Si_(13.5)B_9纳米晶合金进行二次热处理,可以不同程度地减小合金的饱和磁致伸缩程度。然而,磁场退火后纳米晶合金在较低温度下的初始磁导率出现了不同程度的降低,原因可以归结为:在磁场退火的过程中,感生出的单轴各向异性增加了合金总的各项异性。     

纳米晶Fe-Cu-Nb-Si-B系合金的感生磁各向异性和磁性

纳米晶Ｆｅ-Ｃｕ-Ｎｂ-Ｓｉ-Ｂ系合金的感生磁各向异性和磁性日立公司磁性材料研究所吉泽先生等人报道了他们对纳米晶Ｆｅ-Ｃｕ一Ｎｂ—Ｓｔ-Ｂ系合金磁场处理后感生磁各向异性和磁性的研究结果。利用单辊法制得的厚约１８卜。的Ｆｅ--Ｃｕ-Ｎｂ-Ｓｔ-Ｂ非晶合金薄带，卷?..     

Fe73.5Cu1Nb3Si13.5B9纳米晶铁芯的应力退火研究

将环状Fe73．5Cu1Nb3Si13．5B9非晶合金在540℃应力退火,形成具有蠕变感生各向异性的Fe73．5Cu1Nb3Si13．5B9纳米晶铁芯。在炉冷条件下,应力退火的剩磁Br随退火时间的延长可降至0．22T;退火时间超过20min后,Br无明显改变。炉冷条件下获得的剩磁要低于空冷的剩磁。应力的作用对晶化过程中析出相的微观结构没有影响。     

零磁伸非晶合金的λ_s与退火温度的关系

非晶合金没有磁晶各向异性,其磁伸应力各向异性在磁化过程中起重要作用.在发现(Fe_(1-x)Co_x)_(75)Si_(15)B_(10)系列的λ_s在x=0.94处过0以后,已对不少零磁伸合金进行了研究,但关于热处理对λ_s大小的影响尚未见报道.最近,作者提出了一种用冲击法通过张应力感生各向异性测量软磁薄带λ_s的方法,建立了相应的装置,测量了几种零磁伸非晶合金在不同温度退火后的λ_s,得到一组初步结果.     

新型铁基纳米晶合金软磁性能的研究

本文研究了(FeCo)73．5Cu1Nb3(SiB)22．5铁基纳米晶合金在不同退火条件下的磁性能。与典型成分的Finemet合金相比，该合金铁损和矫顽力很低，有优良的综合软磁性能且磁场退火效果很好，这种更好的磁场退火效果来源于该合金有大的磁感生各向异性常数Ku。     

纵向磁场动态电脉冲快速退火FeBSi非晶合金的力性与磁性

采用动态电脉冲纵向磁场退火法，对Fe78B13Si9非品合金条带实施连续快速退火．测定了该合金条带的应力松弛、退火脆化及软磁性能随动态脉冲加热工艺参数的变化规律．试验结果表明，适当的动态脉冲加热工艺参数的配合，可以使Fe78B13Si9非晶合金条带的液淬内应力基本上完全松弛，磁性能优于最佳常规退火处理的条带性能，同时也完全消除了退火脆化现象．     

纵向磁场动态电泳冲快速退火FeBSi非晶合金的力性与磁性

采用动态电脉冲纵向磁场退火法，对Ｆｅ７８Ｂ１３Ｓｉ９非晶合金条带实施连续快速退火，测定了该合金条带的应力松弛，退火脆化及软磁性能随动态脉冲加热工艺参数的变化规律，试验结果表明，适当的动态脉冲加热工艺参数的配合，可以使Ｆｅ７８Ｂ１３Ｓｉ９非晶合金条带的液淬内应力基本上完全松弛，磁性能优于最佳常规退火处理的条带性能，同时也完全消除了退火脆化现象。     

去应力退火对Ti40合金力学性能的影响

Ti40合金常规热处理后进行不同温度的去应力退火,观察并测试合金在不同去应力退火后的组织和力学性能。结果表明,不同的去应力工艺对材料的力学性能有较大的影响。当去应力温度在500℃到550℃之间时,Ti40合金室温、高温力学性能的强塑性匹配达到最好,此时持久性能虽有所降低,但能满足使用要求;而当去应力温度达到600℃以上时,合金的强度变化不大但是塑性急剧下降。推荐550℃×4 h为合金常规热处理后的最优退火工艺。     

Magnetic properties of nanocrystalline FeMCuNbSiB alloys (M: Co,Ni)

The magnetic properties and microstructure of nanocrystalline FeMCuNbSiB alloys (M: Co, Ni) annealed under a transverse field have been studied. Large induced magnetic anisotropy and good properties in the high frequency range were obtained in Co-rich nanocrystalline FeCo(Cu)NbSiB alloys.     

Magnetic properties and time-temperature stability of properties of on iron-and cobalt-based amorphous and nanocrystalline alloys with a destabilized domain structure

Magnetic properties of amorphous and nanocrystalline alloys with a saturation magnetostriction close to zero and a destabilized magnetic domain structure have been studied. A change in the magnetic characteristics has been investigated after two treatments leading to a destabilization of the domain structure: magnetic annealing in a high-frequency magnetic field of 80 kHz and quenching in water. It has been shown that the destabilization by both the first and the second methods markedly improves magnetic properties of amorphous alloys. Nevertheless, upon quenching of amorphous alloys a time-temperature instability of the magnetic properties has been observed. The quenching in water of the nanocrystalline alloys under study results in a deterioration of the magnetic properties.     

FeCoNiSiB非晶合金感生各向异性对磁性能的影响

研究了恒温张力退火和横磁退火工艺对FeCoNiSiB非晶合金各向异性及磁性能的影响。结果表明,合金经恒温张力退火后表现出高直流偏置性能和高损耗的特点,而经横磁退火后具有优异的综合软磁性能,即具有高直流偏置能力的同时具有低损耗的特点。其中,恒温张力退火过程中提高退火温度时合金直流偏置能力增加,550 ℃下张力退火5 min的直流偏置场强度H_0.98为195 A/m,对应的损耗值P_cm为7255 W/kg;而经450 ℃横磁退火后,合金直流偏置场强度H_0.98可达374 A/m,对应的损耗值P_cm仅为200 W/kg。除此之外,经恒温张力退火和横磁退火后FeCoNiSiB非晶合金内部均形成180°条形磁畴结构,但其磁化矢量方向分别平行和垂直于磁化方向。     

冷却速率对FeSiBCuNb合金条带磁学和耐腐蚀性能的影响

采用X射线衍射仪(XRD),振动样品磁强计(VSM),电化学工作站以及扫描电子显微镜(SEM)等试验仪器对辊速为14.65和43.96 m/s旋淬制备的Fe_73.5Si_13.5B₉Cu1Nb₃(C1和C2)合金条带进行了测试分析。XRD结果显示,低冷速下制备获得了非晶/纳米晶双相(C1)合金,高冷速制备的合金(C2)为非晶态。VSM结果显示,C1和C2合金均具有优异的软磁性能。低冷速制备的纳米晶(C1)合金相比高冷速制备的非晶态(C2)合金具有较强的磁各向异性,C1合金磁各向异性的增强是由纳米晶相的键对有序性以及纳米晶相与非晶基体相互作用引起的磁弹各向异性所致。合金的电化学测试显示,C2合金耐腐蚀性能要好于C1合金,合金耐腐蚀性能的差异与制备过程中不同冷速所导致的合金表面组织结构和应力不均匀性相关。     

Precipitation of a-Fe from Fe84-xSi4B12+x (x=1,3) Amorphous Alloys Under High Magnetic Field Annealing

This work aims to investigate the effects of high magnetic field annealing (HMFA) on the precipitation of α-Fe from Fe84-xSi4B12+x (x =1,3) amorphous precursors.Isothermal annealing process for Fe81Si4B15 and Fe83Si4B13 amorphous ribbons has been performed with and without the magnetic field.The magnetic field shows the effects of increasing the nucleation rate and decreasing the grain size of α-Fe crystals simultaneously,during the crystallization processes of the investigated amorphous alloys.By applying HMF,α-Fe crystals with more homogeneous distribution and smaller grain size are achieved in the amorphous matrix,which is crucial helpful to improve the magnetic properties for Fe-Si-B amorphous alloys.The mechanism of HMFA affecting the crystallization microstructure is also discussed in the present work.     

Magnetic properties of Fe-Co-Mo-Cu-B nanocrystalline ribbons with stressing surfaces

Magnetic properties of Fe-Co-Mo-Cu-B alloy system with Co up to 26 at.% were investigated. After proper thermal treatment, the nanocrystalline grain remains tiny, the density hardly increases, but the room-temperature saturation attains 1.5 T mainly due to a high enough Curie temperature. The generally observed slant hysteresis loops point to ribbon surfaces, which stress the ribbon interior and induce a specific magnetoelastic contribution to hard-ribbon-axis magnetic anisotropy even after vacuum annealing. The effect does not come from cobalt but rather from the lack of silicon. Partial removal of the surfaces resulted in a decrease of the loop tilt.     

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.     

熔体温度对快淬法制备纳米晶复合Nd_(8.5)Fe_(77)Co_5Zr_3B_(6.5)合金微观结构和磁性能的影响

将Nd_(8.5)Fe_(77)Co_5Zr_3B_(6.5)(at%)合金熔化至不同温度后,以18 m/s的甩带速度快淬,对淬态条带进行了退火处理,分析了其微观结构和磁性能的变化。结果表明,熔体温度对淬态及其退火态合金的微观结构和磁性能可以产生重要影响,熔体温度为1210℃时制备的快淬条带由Nd_2Fe_(14)B相和部分非晶相组成,具有一定的硬磁性;随着快淬时熔体温度的升高,淬态条带中非晶相的质量分数逐渐增加,其磁性逐渐转变为软磁性。几种合金经退火处理后均由大量Nd_2Fe_(14)B相与少量软磁相组成,熔体温度较低的合金退火后其晶粒尺寸较小,磁性能较好。熔体温度为1210℃时制备的合金退火后磁性能最佳,内禀矫顽力Hci为559.2 kA/m,剩余磁化强度Br为0.98 T,最大磁能积(BH)_(max)为127.8 kJ/m~3。