Non-monotonic influence of a magnetic field on the electrochemical behavior of Fe78Si9B13 glassy alloy in NaOH and NaCl solutions

The corrosion behavior and microstructure of Fe78Si9B13 glassy alloy in NaOH and NaCl solutions under a 0.02-T magnetic field were investigated through electrochemical testing and scanning electron microscopy （SEM）. The current-density prepeak （PP） in the anodic polarization curves in low-concentration NaOH solutions （classified as type I） tends to disappear when the NaOH concentration is increased to 0.4 mol/L and the magnetic field is applied. Under the magnetic field, the height of the second current-density peak is increased in low-concentration NaOH solutions （type I） but decreased in high-concentration NaOH solutions （type Ⅱ）. The non-monotonic effect of the magnetic field was similarly observed in the case of polarization curves of samples measured in NaCl solutions, Ring-like corroded patterns and round pits are easily formed under the magnetic field in NaOH and NaC1 solutions. These experimental results were discussed in terms of the magnetohydrodynamic （MHD） effect.     

The mechanism study on annealing embrittlement of Al_(88)Ce_2Ni_9Fe_1 metallic glass

The mechanism of annealing embrittlement of Al88Ce2Ni9Fe1 metallic glass is studied by using SAXS. For this alloy the activation energy for embrittlement, Eb=(160±10) kJ·mol-1 is obtained It approaches the value of the activation energy for crystallization, Ec= (170± 10} kJ·mol-1 . The significant change in SAXS intensity is observed as the sample transformed from the ductile to the brittle state. About 0. 1 volume fraction of Al crystalline particle and 60 m2/cm3 of specific inner surface between crystalline and amorphous phase appear as the sam ple transformed from the ductile to the brittle state. The annealing embrittlement is caused by crystallization of this alloy.     

Crystallization of Pd40Cu30Ni10P20 bulk metallic glass with and without pressure

The glass-transition behavior of Pd40Cu30Ni10P20 bulk metallic glass was investigated by differential scanning calorimetry （DSC） and X-ray powder diffraction （XRD）. The effect of pressure on the crystallization behavior of Pd40Cu30Ni10P20 bulk glass was studied by in situ high-pressure and high-temperature X-ray powder diffraction using synchrotron radiation. Phase analyses show at least six crystalline phases in the crystallized sample, namely, monoclinic, tetragonal CuaPd-like, rhombohedral, fcc-Ni2Pd2P, fcc-（Ni, Pd） solid solution, and body-centered tetragonal （bct） NiaP-like phases. The onset crystallization temperature increases with pressure having a slope of 1 1 K/GPa in the range of 0 to 4 GPa. The results are attributed to the competing process between the thermodynamic potential barrier and the diffusion activation energy under pressure.     

Crystallization of Fe78Si9B13 Bulk Crystaline/Amorphous (c/a) Composite

A metallic crystalline/amorphous (c/a) bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction (XRD),differential scanning calorimetry (DSC) and scanning electron microscope (SEM), the composite consists of the primary dendrite a-Fe (without Si) as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays (EDAX), SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy （Fe, Co）-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) and [(FexCo1-x)0.72B0.192Si0.04]Nb0.04]96Y4 (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability,and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding lat% to 6at% of yt-trium, the bulk glassy alloy rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe1-xCox)B0.192Si0.048Nb0.04]96Y4 (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (Ms) increased.     

Plastic deformation behavior of Fe_(40)Ni_(40)P_(14)B_6 bulk metallic glass investigated by nanoindentation

Fe40Ni40P14B6 bulk metallic glass rods have been prepared by water quenching the fluxed alloy. The deformation behavior was investigated by nanoindentation tests and compressing tests. The average hardness and elastic modulus of the as-prepared Fe40Ni40P14B6 BMG (bulk metallic glass) measured by nanoindentation tests are 8.347 and 176.61 GPa respectively. The displace- ment-load curve shows “pop-in” characteristics which correspond to the loading rate bursts. Many shear bands around the indent were observed. The as-prepared Fe-based BMG exhibits a compressive plastic strain of 5.21%, which is much larger than that of other Fe-based glassy alloys and most of other BMGs.     

两种处理工艺下Fe_(78)Si_9B_(13)非晶薄带的磁致伸缩系数

采用低频脉冲磁场和等温退火工艺分别对非晶合金Fe78Si9B13样品进行处理,用自制磁致伸缩测量系统对处理前后样品的磁致伸缩系数进行测量。实验结果表明,两种处理工艺都使样品的饱和磁致伸缩系数λs减小,饱和磁致伸缩系数与退火时间t有关,在300℃温度下等温退火40min,样品的饱和磁致伸缩系数最小,其值为49.52×10-5。饱和磁致伸缩系数λs与低频脉冲磁场强度Hp为非线性关系,饱和磁致伸系数λs对脉冲磁场处理参数有所选择,当Hp为19 900A/m、脉冲频率f为30Hz、t为240s时,饱和磁致伸缩系数最小,其值为2.70×10-5。低频脉冲磁场处理对样品的饱和磁致伸缩系数的影响明显大于等温退火。     

Nd_(60)Al_(10)Ni_(10)Cu_(20)大块金属非晶的玻璃转变和晶化特性研究

用铜模吸铸法制得了一种直径为5 mm、成分为Nd60Al10Ni10Cu20的大块非晶合金.与富Fe类Nd基非晶不同的是,这种新型的Nd基大块非晶具有明显的玻璃转变过程和稳定的过冷液相区.磁性测试表明,在室温下表现为顺磁性.热分析实验发现,随着升温速率的增大,样品的过冷液相区变宽,并且玻璃转变温度和晶化温度有明显的向高温方向移动的趋势.研究了该大块非晶的玻璃转变动力学和晶化动力学,并给出了Kauzmann温度Tk,Vogel-Fulchers-Tamman温度T0g以及脆性系数m等重要参数.     

Adsorption Capacity of Kaolinite for Copper （Ⅱ） under Magnetic Field

The adsorption of Cu^2 on kaolinite under magnetic field was studied at 25℃.The magnetic effects were investigated by designing the variation of exposure time, rnagnetie flux density and the method of magnetic exposure. The results from these study show that the magnetic treatment significaatly enhance the fraction of adsorption of Cu^2 ,the adsorption of Cu^2 by kaolinite increases with the increase of pH value from 2 to 6. Both the magnetic exposure time and the magnetic flux density promote the fruetion of adsorption Cu^2 on kaolinite.     

Microstructure refinement and magnetic properties enhancement of nanocrystalline Nd_(12.3)Fe_(81.7)B_(6.0) ribbons by addition of Zr

Effects of Zr addition and annealing treatment on the formation, microstructure and magnetic properties of Nd12.3Fe81.7?xZrxB6.0 (x=0―3.0) ribbons melt-spun and annealed have been systematically investigated by means of vibrating sample magnetometer (VSM), differential scanning calorimeter (DSC), X-ray diffraction (XRD), and high resolution scanning electron microscopy (HRSEM). Phase analysis reveals that Nd2Fe14B is single-phase material. It has been found that the intrinsic coercivity Hci of the optimally...     

低频高梯度磁场频率对碳酸钙结垢的影响研究

使用自制高梯度磁场处理器进行阻垢实验,通过XRD、阻垢率和电导率的检测分析,研究磁场频率对碳酸钙结垢的影响,结果表明,低频范围内垢样中文石含量随着频率的增加而增加,在频率为25 Hz时,文石含量达到最大值,方解石含量最少,抑制了文石向方解石的转化;且文石含量越高,阻垢率越大,增大了溶液中的钙离子浓度,阻垢效果越好.     

La_(1-x)Pr_xFe_(11.4)Si_(1.6)(x=0.1,0.2,0.3)金属间化合物的晶体结构和磁熵变研究

通过X射线和磁性测量等手段对所制备的金属间化合物La1-xPrxFe11.4Si1.6(x=0.1,0.2,0.3)的结构和磁性进行了研究.结果表明,在1 373 K温度下,经过50 d退火所得的化合物均形成了单相立方NaZn13型结构;部分Pr替代La原子后,会引起晶格畸变;另在外磁为1.5 T时,Pr含量为x=0.1,0.2,0.3时的最大磁熵变|ΔS(T,H)M|max分别为15.06,37.08和15.22 J/kg.K.大的磁熵变来源于TC处磁化强度的陡峭变化和TC以上磁场诱发的巡游电子变磁转变.     

熔体过热度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响

为了研究合金熔体过热度和退火温度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响,在180、200和230℃3个不同合金熔体过热度下利用单辊法制备了宽142 mm、厚23μm的非晶条带.在350~370℃范围内选取5个退火温度对非晶条带进行纵向磁场退火,并利用硅钢测试仪对退火后的非晶条带进行磁性能测试.结果表明,随着合金熔体过热度的增大,非晶条带的激磁功率和损耗均呈下降趋势.随着过热度和退火温度的降低,非晶条带的磁性能分布区间变窄,但其稳定性增强.适当提高过热度和热处理温度有助于获得具有最佳磁性能的非晶条带.     

SuperDARN CUTLASS Finland radar observations of high-latitude magnetic reconnections under northward interplanetary magnetic field (IMF) conditions

A number of backscatter power enhancement events with "equatorward-moving radar auroral forms" in the high-latitude ionosphere were observed by SuperDARN CUTLASS Finland radar when the IMF was northward during 09:00 -10:00 UT on 26 March 2004. These events were also associated with sunward flow enhancements at each location in the Northern Hemisphere which were shown in ionospheric convections measured by the SuperDARN radars. These are typical features of high-latitude (lobe) magnetic reconnections. The durations of the velocity enhancements imply that the evolution time of the lobe reconnections is about 8-16 min from their origin at the reconnection site to their addition to the magnetotail lobe again. In additional, the Double Star TC-1 spacecraft was moving from magnetosheath into magnetosphere, and crossing the magnetopause near the subsolar region during this interval, and observed typical low-latitude magnetic reconnection signatures. This infers that the dayside high- and low-latitude reconnections may occur simultaneously.     

Crystallization of Fe78Si6B13 Bulk Crystaline/Amorphous （c/a） Composite

A metallic crystalline/amorphous （c/a） bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction （XRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）, the composite consists of the primary dendrite α-Ee （without Si） as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays （EDAX）, SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.