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。     

温度对退火态6.5%Si-Fe热轧合金塑性的影响

本文研究了退火态 6 .5 %Si Fe热轧合金在不同温度下拉伸时的力学性能 ,并观察了拉伸断口形貌及退火态 6 .5 %Si Fe热轧合金的金相组织。结果表明 ,经 75 0℃保温 140min后 ,6 .5 %Si Fe热轧合金的层状组织消除 ;其断裂模式随拉伸温度的升高迅速由解理断裂向韧性断裂转变 ;在 2 0 0℃拉伸时 ,为纯解理断口 ,此时该合金即具有高达 2 6 %的延伸率 ;但是在 2 0 0℃ - 40 0℃温区 ,延伸率未随温度的升高而显著增大 ,其断口形貌为解理 +韧窝的混合断口 ;在 5 0 0℃拉伸时 ,为纯韧窝断口 ,其延伸率可达 43 %     

温度对退火态6.5%Si—Fe热轧合金塑性的影响

本文研究了退火态6.5%Si-Fe热轧合金在不同温度下拉伸时的力学性能，并观察了拉伸断口形貌及退火态6.5%Si-Fe热轧合金的金相组织。结果表明，经750℃保温140min后，6.5%Si-Fe热轧合金的层状组织消除；其断裂模式随拉伸温度的升高迅速由理解断裂向韧性断裂转变；在200℃拉伸时，为纯解理断口，此时该合金即具有高达26%的延伸率；但是在200℃-400℃温区，延伸率未随温度的升高而显著增大，其断口形貌为解理 韧窝的混合断口；在500℃拉伸时，为纯韧窝断口，其延伸率可达43%。     

热处理对Fe_(79.5)P_(12)C_6Cu_(0.5)Mo_(0.5)Si_(1.5)软磁合金薄带的巨磁致阻抗效应(GMI)的影响

研究了不同温度热处理对Ｆｅ７９．５Ｐ１２Ｃ６Ｃｕ０．５Ｍｏ０．５Ｓｉ１．５的巨磁阻抗的影响，发现ＧＭＩ不仅与磁导率有关，而且也受到磁各向异性的作用。     

大块深过冷Al-Mn-(Si,B)合金准晶相的初生凝固

用“玻璃覆盖、熔盐净化及热循环”复合方法实现了大块Al－Mn－（Si;B）熔体的深过冷,获得了100K的过冷度,并自发生成准晶相．研究了准晶相的形核及生长形貌特点,结果表明,准晶相为初生凝固相．初生准晶相的形成归因于推晶相的固液界面能低于竞争晶体相.     

机械合金化工艺对Mg_(60)Zn_(30)Ti_5Si_5非晶合金制备的影响

采用机械合金化方法制备Mg60Zn30Ti5Si5非晶合金并研究工艺参数对其的影响规律。主要通过X射线衍射(XRD)分析不同条件下制备的试样的物相组成;并结合扫描电子显微镜(SEM)、差示扫描量热分析(DSC)检测试样微观形貌及热性质。结果表明:原料粉末首先发生合金化形成中间化合物,然后转变成非晶;球料比17.5∶1、球磨时间6h、转速425r/min是较优的工艺参数;三个工艺参数中,球料比是形成非晶的关键因素;Mg60Zn30Ti5Si5合金在加热过程中放热量大小与非晶含量相关。     

(Si+Mn)/Fe对Al-5Cu合金铸态组织及力学性能的影响

在Al-5Cu-0.3Fe高强铸造合金中添加Mn和Si,采用OM、SEM、EDS及DSC等分析方法研究(Si+Mn)/Fe质量比(K=3、4、5和6)对其铸态组织及力学性能的影响。结果表明：随着K值的增大,富Fe相形貌的变化趋势为针状→汉字状→粗大汉字状富Fe相聚集,富Fe相由针状Al₃FeMn向汉字状Al₆FeMn转变。Al-5.0Cu-0.3Fe-1Si-xMn合金,K=4时,拉伸断口展现良好的塑性特征,合金的综合力学性能最佳,比K=3时抗拉强度和延伸率分别提高了22%和65%。Si和Mn元素对Al-5.0Cu-0.3Fe合金的富Fe相有良好的变质作用。适当减少Mn的添加量,而增加Si的含量,保持(Si+Mn)/Fe=4,有助于减少合金的孔洞缺陷,降低热裂敏感性,较好地调控富Fe相形貌和尺寸。     

Si对AZ91D镁合金显微组织与力学性能的影响

利用光学金相显微镜OM和XRD分析了加入微量Si的AZ91D合金显微组织和相组成,测试了合金室温拉伸力学性能和硬度,利用SEM分析了合金拉伸断口形貌.结果表明,加入一定量Si后AZ91D合金组织中形成汉字状Mg2Si相,富集于固液界面前沿,阻碍α-Mg基体的自由长大,从而细化合金铸态组织;汉字状Mg2Si相的存在导致合金力学性能的降低;AZ91D合金室温拉伸断口是以解理断裂为主的脆性断裂,加入Si后,断裂常发生于α-Mg基体和汉字状Mg2Si相间的界面处.     

NiCoCrAlY(Si)梯度涂层对Ni3Al基单晶合金IC6SX抗氧化性能的影响

采用超音速火焰喷涂的方法在Ni3Al基单晶合金IC6SX上涂覆了NiCoCrAlYSi/NiCoCrAlY梯度涂层,研究了涂层对IC6SX合金1100℃抗氧化性能的影响.利用扫描电镜、X射线衍射等手段观察了氧化试样的微观结构,分析了氧化产物的成分及涂层氧化前后的相组成变化.结果表明:涂层表面形成了致密的氧化膜,氧化膜由内外两层组成,内层主要由Al2O3组成,外层主要由NiAl2O4及少量的Cr2O3组成;涂层有效地控制了Mo元素的扩散氧化,对IC6SX合金的抗氧化性能有明显改善.     

生长参数对Si_(1-x)Ge_x∶C合金薄膜中元素分布的影响

用化学气相淀积方法在Si(100)衬底上外延生长Ge组分渐变的Si1-xGex∶C合金薄膜。本文通过能量色散谱仪(EDS)和扫描电子显微镜(SEM)对合金薄膜的元素深度分布和表面形貌进行了表征,分析研究了外延层的生长温度、生长时间对Si1-xGex∶C合金薄膜性质的影响。结果表明,Si1-xGex∶C外延层生长温度和生长时间一定范围内的增加加强了岛与岛之间的合并,促进了衬底Si原子向表面扩散、表面Ge原子向衬底扩散,且生长温度比生长时间对Si、Ge原子互扩散的影响大。     

Strain-softening behavior of an Fe-6.5 wt%Si alloy during warm deformation and its applications

An Fe-6.5 wt%Si alloy with columnar grains was compressed at a temperature below its recrystallization temperature. The Vickers hardness and structure of the alloy before and after deformation were investigated. The results showed that with an increase in the degree of deformation, Vickers hardness of the alloy initially increased rapidly and then decreased slowly, indicating that the alloy had a strain-softening behavior after a large deformation. Meanwhile, the work-hardening exponent of the alloy decreased significantly. Transmission electron microscopy confirmed that the decrease of the order degree was responsible for the strain-softening behavior of the deformed alloy. Applying its softening behavior, the Fe-6.5 wt%Si alloy with columnar grains was rolled at 400 °C and then at room temperature. An Fe-6.5 wt%Si thin strip with thickness of 0.20 mm was fabricated. The surface of the strip was bright and had no obvious edge cracks.     

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.     

喷射轧制Fe-4.5%Si硅钢片的组织和性能

采用喷射成形和轧制工艺制备了厚度为0.5mm的Fe-4.5%Si高硅钢片，并对其密度、显微组织和电磁性能进行了测试分析，研究结果表明：在最佳的喷射成形和轧制工艺条件下，所制备硅钢片的磁感应强度B25为1.544T、B50为1.641T；铁损P1050为1.437W/kg、P1550为3.43W/kg，说明喷射成形轧制技术可以制备出高磁感应强度、低铁损的高硅钢片。     

Numerical study of heat transfer and solidification behavior of gas-atomized Fe-6.5%Si (mass fraction) droplets

During spray atomization process, the heat transfer and solidification of droplets play very important roles for the deposition quality. Due to the difficulties of experimental approach, a numerical model is developed, which integrates liquid undercooling, nucleation recalescence and post-recalescence growth to present the full solidification process of Fe-6.5%Si (mass fraction) droplet. The droplet velocity, temperature, cooling rate as well as solid fraction profiles are simulated for droplets with different sizes to demonstrate the critical role of the size effect during the solidification process of droplets. The relationship between the simulated cooling rate and the experimentally obtained secondary dendrite arm spacing is in excellent agreement with the well-established formula. The pre-constant and exponent values lie in the range of various rapid solidified Fe-based alloys reported, which indicates the validity of the numerical model.     

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-Si-Al三元体系中Si、Al共渗的交互作用机制。设计结构为17.5 μm Fe-34.2%Si-8.93%Al /200 μm Fe-3%Si /17.5 μm Fe-34.2%Si-8.93%Al的扩散偶组合,模拟其在1 373 K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14 400 s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。     

Processing of Fe-6.5wt.%Si alloy foils by cold rolling

Thin foils of 50 μm in thickness of Fe-6.5wt.%Si alloy were obtained by conventional hot-cold rolling method. The rolling texture and basic mechanical properties of the foils were examined. The foils were heavily work-hardened and exhibited high tensile fracture strength with some extent of plastic elongations. Their bending ductility was more remarkable.     

PVD法渗Si制备6.5%Si高硅钢过程组织结构与性能演化研究

基于物理气相沉积(PVD)之直流磁控溅射镀膜技术在低硅钢薄板双面共沉积富Si膜,然后高温真空扩散处理使Si渗入低硅钢基体,提高基体含Si量。以沉积Fe5Si3膜+1 180℃×1h扩散为1回合增Si处理,研究了多回合循环增Si处理过程硅钢基体组织结构与性能的演化机理。采用光学显微镜对样品进行了金相分析,采用扫描电镜(SEM)观察了样品的微观组织形貌,并用能谱分析仪(EDS)进行成分分析。用X射线衍射仪(XRD)和透射电镜(TEM)表征了样品的结构特征。经过4回合循环增Si处理可将0.35mm厚低硅钢基体含Si量由3%提高到6.5%,且沿厚度方向Si浓度分布均匀。相比于初始态低硅钢基片,PVD法制成6.5%Si高硅钢中高频铁损值降低40%~50%。     

强磁场下电磁振荡频率对Al-18wt%Si合金初生硅分布和形貌的影响

为确定电磁振荡频率对初生硅的影响,本文选用Al-18wt%Si合金,研究了强磁场与工频、中频两个频率的交变电流复合作用产生电磁振荡对初生硅分布和形貌的影响规律.结果表明:振荡频率对Al-18wt%Si合金初生硅的分布影响不大,而对其形貌产生较大的影响,随着频率的增大,初生硅由板条状转变成颗粒状.