Effect of 0.5 mass% Cu Addition on Ductility and Magnetic Properties of Fe-6.5Si Alloy

The effect of adding 0.5mass% Cu on ductility and magnetic properties of Fe-6.5Si（mass%）alloy was investigated.The alloys with and without 0.5mass% Cu addition were warm rolled into thin sheets of thickness no more than 0.3mm at temperature below 600 ℃.It was found that the alloy with 0.5mass% Cu addition was more easily warm rolled than Cu-free alloy.Tensile tests were carried out to further investigate this phenomenon,which confirmed that the ductility of the alloy with 0.5mass% Cu addition was significantly higher than that of Cu-free alloy at 550 ℃.Based on the results of transmission electron microscopy analysis,the ductility increase of the alloy with 0.5mass% Cu addition was attributed to the effect of Cu on the promotion of dynamic recovery and suppression of long-range order in the alloy during warm rolling process.It was also observed that the iron loss was lower and inductance was higher for the alloy with 0.5 mass% Cu addition.Thus,it can be concluded that adding a suitably small amount of Cu would not only increase the ductility of Fe-6.5Si alloy at warm rolling temperatures but also improve its magnetic properties.

Effect of Deformation Temperature on Deformation Mechanism of Fe-6.5Si Alloys with Different Initial Microstructures

Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe 6.5Si （mass%） alloys fabricated by directional solidification and equiaxed grained Fe-6.5Si alloy fabricated by forging were comparatively investigated. The results showed that, with increasing the deformation temperature from 300℃ to 500℃, the elongation increased from 2.9% to 30.1% for the equiaxed-grained Fe-6.5Si alloy, while from 6.6% to about 51% for the columnar-grained Fe-6.5Si alloy. The deformation mode of equiaxed-grained Fe 6.5Si alloy trans ferred from nearly negligible plastic deformation to large plastic deformation dominated by dislocation slipping. Comparatively, the deformation mode of the columnar grained alloy transferred from nearly negligible plastic deformation to plastic deformation dominated by the twining, and finally to plastic deformation dominated by dislocation slipping. Meanwhile, compared with the alloy with equiaxed grains, it was found that ultimate tensile strength and elongation could be increased simultaneously, which was ascribed for the twinning deformation in columnar-grained Fe-6.5Si al loy. This work would assist us to further understand the plastic deformation mechanism of Fe-6.5Si alloy and pro vide more clues for high-efficiency production of the alloy.

Numerical modeling for electron-beam evaporated process of magnetic alloy Fe-6.5%Si

Based on Langmuir equation and thermodynamic properties of iron-silicon binary alloy, a mathematical model about the process of electron-beam evaporated binary alloy Fe-6.5%Si was established. Variation of the composition of molten pool, vapor and deposit with time, length of transient time and the composition of molten pool, deposit under the steady condition were presented according to the numerical model. The experimental results on the composition of deposit were compared to the data calculated through the model. The results show that the model is applicable, after evaporating for about 50min, the compositions of the deposit are equal to those of the ingot.

Simulation of solidification microstructure of Fe-6.5%Si alloy using cellular automaton-finite element method

3D microstructures of Fe–6.5%Si(mass fraction) alloys prepared under different cooling conditions were simulated via finite element-cellular automaton(CAFE) method. The simulated results were compared to experimental results and found to be in accordance. Variations in the temperature field and solid-liquid region, which plays important roles in determining solidification structures, were also examined under various cooling conditions. The proposed model was utilized to determine the effects of Gaussian distribution parameters to find that the lower the mean undercooling, the higher the equiaxed crystal zone ratio; also, the larger the maximum nucleation density, the smaller the grain size. The influence of superheat on solidification structure and columnar to equiaxed transition(CET) in the cast ingot was also investigated to find that decrease in superheat from 52 K to 20 K causes the equiaxed crystal zone ratio to increase from 58.13% to 65.6%, the mean gain radius to decrease from 2.102 mm to 1.871 mm, and the CET to occur ahead of schedule. To this effect, low superheat casting is beneficial to obtain finer equiaxed gains and higher equiaxed dendrite zone ratio in Fe–6.5%Si alloy cast ingots.

硼元素对Fe-6.5%(质量分数)Si合金力学性能影响的试验研究

含Si约6.5%(质量分数)的Fe Si合金具有优异的软磁性能,但由于其室温脆性差而难以通过常规的冷轧工艺加工成薄板。本文研究了微合金化元素-硼对铸态Fe 6.5%(质量分数)Si合金组织和性能的影响,以及该合金薄板在不同温度下拉伸的力学性能,并观察了拉伸断口形貌。结果表明,硼元素的添加使得该铸态合金晶粒细化,从而提高了该合金的塑性。Fe 6.5%(质量分数)Si合金薄板在不同温度下的拉伸结果表明,室温延伸率达到6.4%,500℃延伸率达最大值(32.96%),明显高于600℃时的延伸率,原因是600℃处于B2和DO3两相区,在温度600℃下发生了DO3相到B2相的转变,使得B2相有所增加。B2相的增加降低了Fe 6.5%(质量分数)Si合金的塑性。

大变形冷轧Fe-6.5%(质量)Si高硅钢薄板组织性能的研究

Fe-6.5%(质量)Si合金具有优异的软磁性能,有着良好的发展前景。但由于该合金中有序相的出现,人们难以用普通轧制的方法得到该合金的薄板。本文利用热轧,温轧,冷轧方法,结合相关的热处理手段,得到该合金0.05 mm薄板。通过在不同温度下热处理,利用光学显微镜,扫描电镜,X射线仪,拉伸机,显微硬度仪,研究该薄板组织结构和力学性能的变化。利用磁滞回线仪研究薄板热处理前后直流磁性能的变化。通过研究发现,0.05mm轧态薄板具有一定的塑性,断裂强度高达1.93 GPa。热处理使薄板硬度降低,塑性降低,特别是在650℃以上,材料发生了再结晶后,变化尤为明显。究其原因是有序相B2向DO3的转变及<001>面织构的消失。

晶界设计和控制及其在Fe-6.5%Si合金中的应用

简要介绍了界面工程学的新概念“晶界设计和控制技术” ,并以Fe 6.5 %Si合金为例 ,展示了这一技术的有效性和可操作性。对原始态快速凝固Fe 6.5 %Si合金薄带的成功分析表明 ,作为晶界设计和控制强有力工具的EBSD分析技术在表征晶界结构方面具有独特的优势。采用适当的铸造、轧制或热处理工艺调整晶界的数量 (晶粒尺寸 )和特征分布 ,不仅能够明显改善Fe 6.5 %Si合金的室温塑性 。

高能球磨制备Fe-6.5%Si合金微粉的研究

Fe-6.5%Si(质量分数)合金具有优异的软磁性能,是高频电机铁芯的理想材料。采用高能行星球磨法制备了Fe-6.5%Si合金微粉。利用激光粒度分布仪、扫描电镜以及X射线衍射仪分别观测了球磨过程中粉末粒度、形貌及结构的变化。结果表明,随着球磨时间的延长,颗粒不断细化,但细化速度逐渐减小;Fe-6.5%Si合金在氩气保护下高能球磨过程中成分稳定,球磨产物为具有亚微米结构的过饱和固溶体;当球磨罐中装料量(mp=100g)一定时,理论计算和球磨实验得出最佳球料比为10∶1。

定向凝固Fe-6.5%Si合金显微组织的EBSD分析

采用定向凝固方法制备了Fe 6 5%Si实验合金板 ,并进行了金相观察、X射线衍射分析、EBSD分析和磁性测定。结果表明 ,合金板由沿定向凝固方向〈1 0 0〉生长的粗大柱状晶所组成 ,柱状晶的平均截面直径约为 3mm。柱状晶之间绝大部分为大角晶界 ,其余为少量小角晶界和重位点阵晶界。合金板具有强的立方织构并显示出优良的软磁性能 ,其矫顽力只有3 45A/m ,小于其他方法制备的Fe 6 5%Si合金。

定向凝固Fe-6.5wt%Si合金热压缩变形行为研究

采用Gleeble 1500热模拟机对定向凝固Fe-6.5%(质量分数)Si合金进行热压缩变形研究。结果表明,Fe-6.5%(质量分数)Si合金柱状晶组织热形变过程中很难发生动态再结晶,以动态回复为主,易产生严重的变形带;在无序相区间,在柱状晶晶界处发生动态再结晶形核,但长大受到限制,仅局限于晶界附近。与锻态等轴晶组织相比,有序相区间,两种组织形变行为基本一致,受温度影响剧烈,在无序相区间,随温度升高,等轴晶组织的形变激活能略有升高,平均值约为294kJ/mol,而柱状晶组织的形变激活能逐渐降低,平均值约为260kJ/mol。

Fe-6.5Si合金热轧板显微组织的TEM观察

采用透射电镜(TEM)研究了高温轧制、中温轧制以及轧制后退火态Fe－6．5Si合金的有序化和微观组织．探讨了该合金有序相和微观组织对常温脆性的影响:结果表明．轧制及退火工艺的不同虽然可以明显改变Fe－6.5Si合金的微观组织及其有序相的尺寸和形态．但是各处理态下均未能完全抑制有序相的形成．同时中温轧制时．该合金中存在严重的应力集中。

中温拉伸Fe-6.5Si合金形变机制的实验观察

采用金相和透射电镜衍衬分析技术研究了 Fe- 6.5Si合金在 2 0 0℃温度下拉伸时的塑性变形行为。结果表明 ,在 2 0 0℃温度下拉伸时 ,该合金的 {1 1 0 }〈1 1 1〉滑移系开动 ,从而在合金中形成形变带。

Fe-6.5%Si/Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9纳米晶复合磁粉芯的制备及其软磁性能研究

采用Fe-6.5%Si粉末复合Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9纳米晶粉末制备了复合磁粉芯,并讨论了Fe-6.5%Si粉末复合量对复合磁粉芯磁性能的影响。结果表明,随着Fe-6.5%Si粉末的添加量从20%增加到80%,复合磁粉芯的密度几乎从5.46g/cm3线性增加到6.01g/cm3。复合磁粉芯的有效磁导率在20～500kHz的频率范围内具有良好的稳定性。随着Fe-6.5%Si粉末添加量从20%增加到80%,复合磁粉芯的有效磁导率几乎从33.7线性增加到38.3。复合磁粉芯的损耗随着Fe-6.5%Si粉末添加量的增加而增加。复合磁粉芯的直流偏置性能随着Fe-6.5%Si粉末添加量的增加而逐渐降低。当直流偏置场为7.96kA/m时,随着Fe-6.5%Si粉末添加量从0增加到80%,复合磁粉芯直流偏置性能从79.6%逐渐下降到62.2%。

Texture Evolutions in Fe-6.5%Si Produced by Rapid Solidification and Chemical Vapor Deposition

Fe-Si ribbons and thin sheets with 6.5%Si content were prepared by means of the single roller rapid solidification and chemical vapor deposition (CVD), respectively. The initial textures of rapidly solidified Fe-6.5%Si ribbons were characteristic of the {100} fiber-type, which became weakened during primary recrystallization in various atmospheres. At the stage of secondary recrystallization, the {100} texture formed in Ar and the {110} texture in hydrogen, while there occurred a texture transformation from the {100} type to the {110} type in vacuum with the increase of annealing temperature. For Fe-6.5%Si sheets prepared by Si deposition in cold-rolled Fe-3%Si matrix sheets, their textures were dominated by the η-fiber (<001>//RD) with the maximum density at the {120}<001> orientations. After homogenization annealing, the η-fiber could evolve into the {130}<001> type or become more concentrated on the {120}<001> orientations, depending on the cold rolling modes of Fe-3%Si matrix sheets.

Hot deformation behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy with acicular microstructure

The characteristics of hot deformation of an α＋β titanium alloy Ti-6.5Al-3.5Mo-1.5Zr-0.3Si with acicular microstructure were studied using isothermal hot compressive tests in a strain rate range of 0.01-10 s^-1 at 860-1 100 ℃. The true stress-tree strain curves of alloy hot-compressed in the α＋β region exhibit a peak stress followed by continuous flow softening; whereas in the β region, the flow stress attains a steady-state regime. At a strain rate of 10 s^-1 and in a wide temperature range, the alloy exhibits plastic flow instability. According to the kinetic rate equation, the apparent activation energies are estimated to be about 633 kJ/mol in the α＋β region and 281 kJ/mol in the β region, respectively. The processing maps show a domain of the globularization process of a colony structure and α dynamic recrystallization in the temperature range of 860-960 ℃ with a peak efficiency of about 60%, and a domain of β dynamic recrystallization in the β region with a peak efficiency of 80%.

Fe-6.5Si合金过喷粉末特性研究

以喷射成形Fe-6.5Si过喷粉末为研究对象,采用OM、XRD、VSM、TEM等手段研究了不同球磨工艺条件下所得合金粉末的组织形貌及微观结构对软磁性能的影响,据此找到较佳的球磨工艺条件.结果表明:Fe-6.5Si合金过喷粉末在366 r·min^(-1)下球磨24 h后,平均晶粒尺寸为25.9 nm.球磨后粉末的磁性能受残余应力和晶粒尺寸的共同影响,在366r·min^(-1)下球磨18 h获得了最佳的磁性能,其饱和磁化强度为205.37 emu·g^(-1),矫顽力为30.096 Oe.

Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2C Alloy

The effects of aging temperature on shape memory effect, mechanical properties and microstruc-ture of Fe-14Mn-5Si-8Cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

Investigation of the Laser Powder Bed Fusion Process of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

Laser powder bed fusion(LPBF)is an advanced manufacturing technology;however,inappropriate LPBF process parameters may cause printing defects in materials.In the present work,the LPBF process of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was investigated by a two-step optimization approach.Subsequently,heat transfer and liquid flow behaviors during LPBF were simulated by a well-tested phenomenological model,and the defect formation mechanisms in the as-fabricated alloy were discussed.The optimized process parameters for LPBF were detected as laser power changed from 195 W to 210 W,with scanning speed of 1250 mm/s.The LPBF process was divided into a laser irradiation stage,a spreading flow stage,and a solidification stage.The morphologies and defects of deposited tracks were affected by liquid flow behavior caused by rapid cooling rates.The findings of this research can provide valuable support for printing defect-free metal components.

基于DICTRA软件模拟Si、Al共渗制取Fe-6.5%Si-1%Al合金薄板

Fe-6.5%Si-1%Al(质量分数)合金薄板具有优异的软磁性能和较好的机械加工性能。本文基于DICTRA (Diffusion controlled transformation)软件模拟研究了Fe-3%Si低硅钢基板Si、Al共渗制取Fe-6.5%Si-1%Al合金薄板的可能条件以及Fe-SiAl三元体系中Si、Al共渗的交互作用机制。设计结构为17.5μm Fe-34.2%Si-8.93%Al/200μm Fe-3%Si/17.5μm Fe-34.2%Si-8.93%Al的扩散偶组合,模拟其在1 373K温度下扩散不同时间后Si与Al的浓度分布。模拟结果表明,低硅钢基体中Si的扩散速率高于Al,当扩散时间达14 400s时,Si与Al沿截面均匀分布,且Si与Al的含量均达到设计目标Fe-6.5%Si-1%Al的成分值。模拟过程中适当改变扩散偶组合中Si与Al的浓度值发现,低硅钢基体Si、Al共渗制取高硅(铝)钢过程中会因活度变化发生Si或Al的上坡扩散,但该影响会在均匀化过程中随浓度梯度的消失而消失。在Fe-Si-Al三元体系中,适量Al的存在会促进Si的扩散。

Fabrication of Fe-6.5wt%Si Bulk by Spark Plasma Sintering

Fe-6.5wt%Si composite compact was fabricated by spark plasma sintering(SPS).Mec hanical alloying(MA)was used to prepare Fe-Si composite powders.The composite p owders were sintered by SPS at elevsated temperature from 500℃ to 700℃.The exp erimental results indicate that the non-equilibrium state of composite Fe-Si i s preserved in the compact.The density of the bulk rises with the increasing tem perature and there is no diffusion of silicon and iron in the interface.