垂直稳恒磁场下Fe-纳米Si颗粒复合电沉积

在垂直稳恒磁场中采用纳米复合电沉积法制备Fe-Si复合镀层.研究了磁场强度和电流密度对阴极电流效率和镀层Si颗粒含量的影响规律,并采用扫描电子显微镜和能谱对所得镀层进行分析.施加垂直磁场后,随着磁场强度增大,阴极电流效率呈现先上升后下降的趋势;镀层Si颗粒质量分数在0.2T达到最大值20.17%,比无磁场下提高了10.4%;镀层表面形貌也发生显著变化,多处形成"山脊","山脊"延伸方向与磁流体力学效应方向一致,分布数量和延伸长度与磁场强度成正比.由于磁流体力学效应,施加磁场还改变了镀层表面气孔形貌,促进氢气的析出.      

水平稳恒磁场下Cu-12％Fe合金的凝固组织

研究了施加磁感应强度1T的水平磁场对Cu-12％Fe合金凝固过程中Fe枝晶形貌、XRD及显微硬度的影响.表明,施加1T水平稳恒磁场后,Fe枝晶显著细化,这主要是由于洛伦兹力和热磁对流竞争作用的结果；XRD分析的结果表明,Cu(111)晶面和Cu(200)晶面所对应的峰值强度均明显大幅度增加；显微硬度的测试表明由于Fe枝晶的细化致使施加磁场后样品的显微硬度小幅度增加.     

镁镍系储氢合金箔的制备研究

根据机械合金化和界面固相扩散反应的基本原理,合成出了一系列不同原子配比的Mg-Ni系储氢合金箔(Mg,Ni原子配比分别是81,41,21及11).研究了Mg-Ni系储氢合金箔的组成及其储氢性能.结果表明,Mg8Ni合金箔的吸放氢温度最低可降至300 ℃,Mg4Ni和Mg2Ni合金箔在250 ℃就可部分氢化,且放氢量均可达到2.5%(质量分数)以上;MgNi合金箔吸氢量较低,但放氢温度有所降低.     

退火处理对钼铼合金箔材性能的影响

钼铼合金具有优良的室温塑性,作为重要元器件应用于电子、半导体等行业。钼铼合金通过粉末冶金工艺方法制备,并经过热轧和冷轧变形,得到需要厚度尺寸的钼铼合金箔材。钼铼箔材还需要进行弯曲、冲压等加工工序制作成零部件应用,对箔材的力学性能有很高的要求。轧制后的退火处理不仅可以消除应力,还有助于改善材料的性能,因此退火处理对于钼铼箔材非常重要。本文通过对0. 05 mm钼铼合金[Mo-35%(质量分数) Re]箔材进行去应力退火、部分再结晶退火和完全再结晶退火等不同退火制度的研究,分析了显微组织的变化,比较了力学性能和杯突性能。试验结果发现,钼铼箔材经过部分再结晶退火处理后,材料具有最优的塑性和杯突值,这对箔材的后续机加工产生有利的影响。     

磁场处理对微合金钢抗腐蚀性能的影响

以于微合金高强度结构钢,抗腐蚀性能非常重要,前人的研究成果主要集中在应力腐蚀,氢致裂纹腐蚀和疲劳腐蚀等方面,关于磁场处理后微合金结构钢抗腐蚀性能的研究未见报道,在微合金钢由奥氏体向铁素转变的过程中施加稳恒磁场,将导致其室温组织发生变化,而组织的改变必然对微合金钢的抗腐蚀性能产生影响,作主要研究了磁场处理后试样的失重量和腐蚀率的变化规律,并提出了斯特方程的修正表达式。     

高拉速时连铸结晶器内钢液湍流场及其电磁控制研究

利用数学模型结合低熔点金属合金模型试验研究全幅二段恒稳磁场控制结晶器内气液两相流场和夹杂物粒子的运动轨迹。结果表明,水口喷吹氩气结合施加恒稳磁场的作用,同时达到控制结晶器内弯月面波动、获得活塞流和抑制后凝固区偏析的目的。氩气喷吹和磁场共同作用既能保持液面稳定又能避免凝结发生。吹入氩气能增加夹杂物的去除率。施加磁场时,夹杂物运动速度明显降低．夹杂物的富集率降低。     

板坯连铸结晶器内电磁制动控制效果的研究

用Pb-Sn-Bi低熔点合金进行了电磁制动模拟实验,研究了单条形稳恒磁场对结晶器内流体流动的控制效果,考察了各操作参数对电磁制动效果的影响。研究表明,电磁制动的控制效果与浇铸速度、水口角度和磁通量密度有关。流体离开水口的冲击深度受磁场的抑制而减小,采用向下45°的水口施加磁场的抑制效果比向下15°的效果要好。     

熔盐电解制取La—Fe合金的研究

用循环伏安法、恒电位电解断电后的电位-时间曲线研究了La(Ⅲ)在NaCl-KCl-LaCl_3熔体中铁电极上还原的电极过程。结果表明在析出纯金属镧之前,形成La-Fe合金,其电荷转移反应是三电子的可逆反应。研究了LaCl_3浓度、阴极电流密度和温度对用铁阴极制取La-Fe合金的电流效率和镧回收率的影响。在850℃附近制取了含La>90wt％的合金,合金由a-La与a-Fe组成。电流效率和回收率均可达90％。     

稳恒磁场对循环电镀液Fe-Si复合电沉积行为的影响

研究了以Fe-50%Si合金颗粒及纯Si颗粒为原料,在稳恒磁场中用循环镀液复合电沉积制备Fe-Si复合镀层,考察了磁场方向、磁感应强度对Fe-Si复合镀层形貌及硅质量分数的影响。结果表明:施加磁场后,随磁感应强度增大,采用Fe-50%Si颗粒和纯Si颗粒获得的镀层硅质量分数显著增加;同时,在梯度磁场力和磁流体力学效应(MHD效应)协同作用下,镀层硅质量分数从边沿至中心呈"平底锅"状分布;电流密度为2A/dm~2、磁感应强度为0.5T时,用Fe-50%Si颗粒电镀获得的镀层硅质量分数达20%。     

外磁场在定向凝固过程中的应用研究

以磁场对合金凝固组织的影响为基础,综述了近年来交变磁场和稳恒磁场在定向凝固过程中的应用和发展,总结了外磁场对定向凝固过程中合金微观组织的作用机制,并展望了今后的研究方向。     

Recovery Improvement of Fine Magnetic Particles by Floc Magnetic Separation

The performance of floc magnetic separation (FMS) has been compared with wet high-intensity magnetic separator (WHIMS). This study was performed on low-grade iron ore slime contained 59.58% Fe with 4.57% silica and 3.78% alumina. Detailed characterization data indicated that a substantial amount of the slime was below 20 µm in size. Beneficiation studies indicated that the FMS process is effective to recover fine hematite and goethite particles, compared with the conventional magnetic separation. In conventional magnetic separation, the extent of the fluid drag force exceeds the magnetic force exerted on ultrafine particles. Thus, ultrafine magnetic particles were usually not recovered effectively by magnetic separators, resulting in the loss of valuable ultrafine slime particles. The FMS process significantly increases the magnetic force on the ultrafine iron ore in the form of hydrophobic flocs in a magnetic field, thus the ultrafine particles can be picked up effectively as magnetic concentrates. The FMS process improved the Fe recovery from 37.35% to 79.60%.     

Magnetic Field-Induced Precipitation Behaviors of Alloy Carbides M2C,M3C,and M6C in a Molybdenum-Containing Steel

The effect of a 12-T high magnetic field on alloy carbide precipitation in an Fe-C-Mo alloy during tempering at an intermediate temperature was investigated. Thin foils and carbon extraction replicas of the treated specimens were examined by transmission electron microscopy (TEM). The results show that the applied high field effectively promoted the precipitation of (Fe,Mo)₆C alloy carbide. The concentration of Fe atom in Fe_6?x Mo _x C carbide is increased whereas that of Mo atom decreased when the high magnetic field was applied. However, the high magnetic field almost had no detectable influence on the atom concentration in (Fe,Mo)₂C and (Fe,Mo)₃C carbides. First principle calculations have been performed to calculate the magnetic moment per iron atom of the carbides to explore the origin of the effect of the magnetic field. The influence of the high magnetic field on the precipitation behaviors of alloy carbides was closely related to the magnetic moment of (Fe,Mo)₂C, (Fe,Mo)₃C, and (Fe,Mo)₆C. The magnetic field promotes the formation of the carbides with high total magnetic moment. The effect of the high magnetic field on the substitutional solute atom (Fe and Mo) concentration change in the three alloy carbides was attributed to their magnetization differences per Fe atom.     

金属注射成形制备Fe-50%Ni软磁合金

以羰基铁粉和羰基镍粉为原料,采用金属注射成形(Metal injection molding,MIM)工艺制备Fe-50%Ni(质量分数)软磁合金,研究烧结气氛、烧结温度和时间以及热处理制度对其磁性能的影响。通过对不同工艺条件下试样的杂质含量、密度、金相和磁性能的分析,发现C、O等间隙杂质原子含量和热处理的冷却方式强烈地影响MIM Fe-50%Ni合金的最大磁导率和矫顽力,而相对密度是影响MIM Fe-50%Ni的饱和磁感应强度和初始磁导率的主要因素。试样经1 380℃氢气烧结3 h、650℃保温1 h再油淬,可获得最佳磁性能:饱和磁感应强度为1.496 T,矫顽力为4.8 A/m,最大磁导率为75.2 mH/m,初始磁导率为9.18 mH/m。     

Morphology and Magnetic Properties of Electrodeposited Iron and Nickel Based Alloy Foils

An alternative to conventional process for the preparation of soft magnetic metal foils of Fe, Fe-Ni, Fe-Co and Fe-Ni-Co by electroforming was described. The microstructure and magnetic properties were observed. The results showed that the crystal size of the iron-based alloy foil is less than 10μm, while that of nickel-based alloy foil is about 2μm. Moreover, the electroformed Fe-Ni foil has better magnetic properties than the conventional milled permalloy 1J79 foil.     

Effects of Magnetic Heat Treatment on Magnetostiction Properties of Tb0.3 Dy0.7 Fe1.95 Alloy

The effects of magnetic heat treatment on magnetostriction properties of Tb0.3Dy0.7Fe1.95 alloy were investigated.The directionally solidified alloy was heated to various temperatures near Curie temperature TC in vacuum, kept for a certain time under the application of magnetic field and then cooled to room temperature.The magnetostriction coefficient was measured by a resistance strain gage.The crystal structure was analyzed by X-ray diffraction (XRD).The experimental results show that the magnetostriction coefficient obviously increases and the grains orientations along the axis changed somewhat as the field of 1 T vertical to axis of the rod-shaped specimen is applied for 5 min at the heating temperature slightly lower than TC.     

氯化物熔盐电解槽磁场模拟

氯化物熔盐电解槽内部磁场的稳定对电流效率的提升非常重要。以50 kA氯化物熔盐电解槽为研究对象，运用有限元软件COMSOL建立电解槽三维电磁场模型，模拟了50 kA电解槽不同平面x、y、z三个方向的磁场强度和电磁力分布特点，重点研究工艺参数对磁场强度和电磁力分布的影响。结果表明，电流增加，每个平面的磁场强度和电磁力均增加，且增幅相同；降低极距、增加电解质液面高度、增加阳极半径均会使磁场强度最大值和电磁力最大值增加。     

Low-temperature magnetic properties of amorphous metal alloys

The magnetic properties of amorphous metal alloys based on iron, silicon, and boron, with additions of other elements, are investigated at liquid-nitrogen temperatures. The magnetization and saturation magnetic field (magnetic hardness) of the alloy depend on the element added (carbon, phosphorus, or nickel). The maximum saturation magnetization is observed for the alloy with carbon, and the maximum saturation magnetic field for the alloy with phosphorus.     

谐波对硅钢片磁性能的影响

针对电机实际运行过程中存在的谐波环境,对不同谐波条件下无取向硅钢片的磁性能进行了研究。采用w(Si)为3%的高牌号无取向硅钢,在磁性测量设备上设置不同次数的谐波,对其磁性能进行了测试。试验结果表明,相对于正弦波条件下的磁性能,3次谐波能造成铁损明显上升;随着谐波次数的增加,谐波引起的铁损会降低并逐渐趋向稳定,但单次谐波对磁感无明显影响;复合多次谐波增加铁损最为显著,并且降低低场下的磁感。     

Effect of Magnetic Field Intensity on Abnormal Microstructure in Fe–1.1%C Alloy

The features of the abnormal microstructure during the austenitic decomposition in Fe–1.1%C alloy under different magnetic field intensity have been investigated by optical microscopy. It was found that the high magnetic field considerably affects the abnormal microstructure in Fe–1.1%C alloy. The high magnetic field increases the area fraction and width of the abnormal microstructure through remarkably decreasing the Gibbs energy needed for the ferrite transformation. Simultaneously, due to the fact that the Ae1 line shifts to high temperature side with the increase of magnetic field intensity, the abnormal microstructure transformation is imposed to stop and the pearlite transformation begins. Therefore, the area fraction of the abnormal microstructure firstly increases and then decreases with the increase of the magnetic field intensity.     

强磁场对铁基合金相变温度和显微组织的影响

The effect of a high magnetic field up to 30 T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morphology of the transformed microstructures and increases the As and A1 temperature. In a magnetic field of 30 T, the A1 temperature increases by about 37.1℃ for Fe-0.8C, the A3 temperature for pure Fe increases by about 33.1 ℃. The measured transformation temperature data are not consistent with calculation results using Weiss molecular field theory. Ferrite grains are elongated and aligned along the direction of magnetic field in Fe-0.4C and Fe-0.6C alloys by ferrite transformation, but elongated and aligned structure was not found in pure Fe, Fe-0.05C alloy and Fe-1.5Mn0.11C-0.1V alloy.