Fe_(78)Si_9B_(13)非晶合金的高温变形性能

通过高温拉伸及胀形实验,研究了Fe78Si9B13非晶合金的塑性变形性能。高温拉伸的温度范围为430℃~530℃,初始应变速率为1.67×10-4s-1~1.67×10-3s-1。利用X射线衍射(XRD)和扫描电镜(SEM)对高温变形后的微观组织进行了分析。高温拉伸的延伸率随温度的升高先增大后减小,450℃时达到最大;在450℃,初始应变速率为8.33×10-4s-1时延伸率为40%。在450℃胀形得到半径为5mm、高4mm的近半球试件,显示了Fe78Si9B13非晶合金具有良好的高温变形性能。高温塑性变形过程中伴随着非晶的晶化,使塑性流动应力增大,影响了Fe78Si9B13非晶合金的高温变形性能。     

Crystallization mechanism of Fe78Si13B9 amorphous alloy induced by ion bombardment

The crystallization behavior of Fe₇₈Si₁₃B₉ amorphous alloys induced by Ar ion bombardment was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. The crystallization process of amorphous alloys can be controlled by adjustment of ion incident angles (θ), beam density and substrate temperature. The compressive stress caused by ion bombardment will result in the decrease of critical nucleation energy and induce the crystallization of amorphous alloy even at very low temperature, and the thermal effect converted from energetic ions will improve the crystallization of amorphous alloys. The crystallization process of amorphous alloy induced by ion bombardment was a stress induced phase transformation process assisted by thermal effect.     

Influence of thermal treatment on structure development and mechanical properties of amorphous Fe73.5Cu1Nb3Si15.5B7 ribbon

Ribbon-shaped amorphous samples with the stoichiometric composition Fe_73.5Cu₁Nb₃Si_15.5B₇ prepared by the melt spinning process were annealed at temperatures ranging from 693 K to 1123 K for 1 h under vacuum. In the early annealing stage, the alloy undergoes a specific nucleation process where Cu clusters precipitate from an amorphous matrix. Further heating initiates the partial crystallization of alloy forming the α-Fe–Si nanocrystallites. Subsequent Vickers hardness tests showed high values depending on the annealing temperature. It was found that the hardening process includes two stages. This behavior correlates well with results of density dislocation calculations. A crystallite size of 10 nm for the α-Fe–Si particles correlated very well with a maximum hardness of the material.     

交流磁场处理对Fe78Si9B13非晶合金结构和性能影响的研究

利用X射线衍射仪(XRD)、振动样品磁强计(VSM)和差示扫描量热仪(DSC)对交流磁场处理前后Fe78Si9B13非晶合金条带的结构和性能进行了分析研究。XRD和VSM结果显示,随着交流电流的增大,合金的近邻原子间距离(d)和矫顽力(Hc)先减小后增大,但饱和磁感应强度则随交变电流的增大而变化幅度不大。d和Hc的变化是由合金中不均匀特征结构在结构磁驰豫过程中的相互作用所导致。由DSC曲线计算获得的表观激活能、局域激活能和局域Avrami指数显示,交流磁场处理提高了合金的初始晶化激活能和晶化反应的Avrami指数,降低了晶化反应的表观生长激活能。合金晶化行为的改变与磁后效导致的团簇原子对有序以及溶质原子与自由体积的扩散有关。     

分步纵磁热处理对Fe3.85Co66.18Si14.5Ni0.97B14.5钴基非晶合金结构和性能的调控

为了制备低磁导率、高矩形比、低矫顽力的钴基非晶合金,对Fe_3.85Co_66.18Si_14.5Ni_0.97B_14.5非晶合金带材采用施加不同热处理工艺,且对其结构和性能进行测试分析的方式进行调控。结果表明,分步纵磁热处理之后的磁芯弛豫焓降低,致密度和有序度增加;在晶化温度之下进行退火的合金都保持非晶态;分步纵向磁场热处理可显著提升磁芯的磁学性能,且当普通热处理温度为480 ℃时,性能最佳,矫顽力0.17 A/m、矩形比96.81 %、1 kHz的有效磁导率为5675.05,且此时的磁畴呈规则的板条状,取向与外磁场呈12.8°的夹角。基于Bertitto模型对其进行损耗分离,发现满足公式P_v=11.05×f×B^0.9814_m+0.7495×f²×B²_m。     

Magnetic properties of Fe75Si10B15 amorphous metallic wires

Effects of the temperature of a preliminary treatment, specimen length, and elastic tensile stresses on magnetic properties of amorphous metallic wires of composition Fe₇₅Si₁₀B₁₅ have been investigated. It has been revealed that the temperature of the pretreatment and the length of the wires have important influence on their magnetic properties. As the wire length decreases, a segment appears in the functional dependence of the differential magnetic permeability of the wire on the external magnetic field where the permeability remains constant, which indicates a change in the fundamental mechanism of magnetization of the wire. It has been shown that the behavior of the experimental functional dependence of the coercive force and differential permeability on applied tensile stresses may be explained in the context of the model of propagation of domain walls that separate oppositely magnetized domains in the core of the wire with allowance for the dissipative term.     

Anodic behavior of Fe40Ni40B20 and Fe39Ni39B10Si12 amorphous alloys

Amorphous alloys Fe₄₀Ni₄₀B₂₀ and Fe₃₉Ni₃₉B₁₀Si₁₂ exhibit a typical active/passive transition when anodically polarized in borate and/or phthalate buffer solutions, at pH = 4.0; 5.3;6.3 and 8.4. There is no large effect of Si on the anodic behaviour of the alloys in these media. Both alloys undergo a typical pitting corrosion in chloride containing solutions, but, the Si bearing alloy is more resistant to the breakdown of passivity. AES analysis revealed a large enrichment in Si within the passivating film formed on the Si bearing alloy, which most probably accounts for its enhanced stability.     

Effect of pulsed laser heating on the magnetic properties of the amorphous alloy Fe76Si13B11

The appearance of magnetic anisotropy has been established by magnetometric methods in the amorphous Fe₇₆Si₁₃B₁₁ ribbon after pulsed laser heating in an external magnetic field. Effects of laser heating on the physical properties of the alloy, in particular, on the Curie temperature and the temperature of crystallization, have been investigated. It is shown that the value of the remanence of the alloy samples after such treatments in a longitudinal magnetic field increases by a factor of more than three. There is suggested a mechanism of the appearance of a uniaxial magnetic anisotropy of amorphous ribbons during the pulsed laser heating in a magnetic field under conditions that do not lead to the crystallization of the alloy.     

Sn和B对Fe基非晶合金条带热稳定性的影响

采用DSC技术检测添加了Sn和B的Fe基非晶合金在不同加热速率下特征温度,并计算出Fe基非晶合金的晶化激活能以分析Sn和B对合金热稳定性的影响。结果表明,加入Sn或B均可使Fe基非晶合金的晶化激活能减小,热稳定性下降。     

FMR study of crystallization in the amorphous alloy Co65Fe4Ni2Si15B14 (Metglas 2714A)

The ferromagnetic resonance technique was used to study the annealing behavior of the metallic glass Co₆₅Fe₄Ni₂Si₁₅B₁₄ (Metglas 2714A). The peak-to-peak FMR linewidth, ΔH_pp, was measured at room temperature and 9.5 GHz for three isothermal annealing times in the temperature range 737–757 K. The transformed fraction, as derived from FMR data, satisfies the Johnson–Mehl–Avrami equation with the exponent n between 0.98 and 1.00. The activation energy for crystallization is estimated from the times to ΔH_pp=25–35 mT to to be 199 kJ mol⁻¹.     

Fe74.5Ni10Si3.5B9C2非晶带的氢致滞后断裂

Ｆ０７４．５Ｎｉ１０Ｓｉ３．５Ｂ９Ｃ２非晶带在恒载荷动态充氢时能发生氢致滞后断裂． 测量了不同充氢电流密度ｉ下的氢致滞后断裂归一化门槛应力σＨＩＣ／σＦ，以及进入试样的氢浓度Ｃ０．结果表明． 当Ｃ０≤６７．４ × １０－４％时．σＨＩＣ／σＦ随ｌｎＣ０上升成线性下降．即σＨＩＣ／σＦ＝１．５９－０．３５　Ｉｎ　Ｃ０：当Ｃ０＞６７．４×１０－４％后，σＨＩＣ／σＦ＝≤０．１，由于实验精度的限制无法测出真实的σＨＩＣ／σＦ值．     

Ordering and grain growth in nanocrystalline Fe75Si25 alloy

The grain growth and ordering behaviors in nanocrystalline Fe₇₅Si₂₅ powders produced by mechanical alloying was studied. In the temperature range 573–703 K, the disordered α-Fe(Si) showed only limited growth with a small activation energy of 32.3 kJ mol⁻¹. However, in the range 773–853 K ordering to DO₃ structure occurred accompanied by a sharp increase in average grain size to a maximum value that depended on the temperature. A grain growth model available in the literature for nanocrystalline materials yielded a good fit to the experimental data. Activation energy of 278.9 kJ mol⁻¹ determined using this model for grain growth is similar to that for lattice diffusion of Si in DO₃ Fe₃Si. The reason for the concurrence of ordering and grain growth is attributed to the Si desegregation at grain boundaries upon ordering transformation. The levels of segregation are estimated from lattice parameter measurements.     

激光熔覆大厚度Fe57Co8Ni8Zr10Si4B13非晶表层及其微结构研究

利用激光熔覆制备出１．２ｍｍ厚的Ｆｅ５７Ｃｏ８Ｎｉ８Ｚｒ１０Ｓｉ４Ｂ１３大厚度非晶表层。用ＸＲＤ,ＥＤＳ,ＴＥＭ,ＤＳＣ及硬度仪对获得的非晶表层进行了多种分析,研究了非晶合金表层的微结构与非晶形成能力,初步探讨了大厚度非晶表层的形成机制。     

放电等离子烧结制备Fe75Zr3Si13B9磁性材料

采用机械合金化技术制备Fe75Zr3Si13B9非晶合金粉体,利用SPS放电等离子烧结技术在不同烧结温度下将非晶合金粉体制备成d20 mm×7 mm的块体非晶纳米晶合金。采用XRD和DSC分析了Fe75Zr3Si13B9非晶合金粉体的相组成、玻璃转变温度Tg、开始晶化温度Tx和晶化峰温度Tp。然后利用XRD、SEM、Gleeble3500、VSM分析不同烧结温度下块体的相转变、微观形貌、力学性能和磁性能。研究表明,在500 MPa的烧结压力下,随着烧结温度的升高,非晶相开始晶化形成非晶纳米晶双相结构,同时,样品的致密度、抗压强度、微观硬度、饱和磁化强度均显著提高。最后在500 MPa的烧结压力和863.15 K的烧结温度下,获得密度6.9325 g/cm3、抗压强度1140.28 MPa、饱和磁化强度1.28 T的非晶纳米晶磁性材料。     

高饱和磁感Fe82Si3.8B13.9C0.3非晶铁芯的退火及浸漆工艺

研究了不同磁场退火和浸漆固化工艺对Fe₈₂Si_3.8B_13.9C_0.3非晶合金环形铁芯损耗和磁性能的影响,并与1K101合金铁芯进行了对比。结果表明:与1K101合金相比,Fe₈₂Si_3.8B_13.9C_0.3合金铁芯的最佳退火温度低于1K101合金,其中纵磁退火时达到最低,为330 ℃。纵磁退火Fe₈₂Si_3.8B_13.9C_0.3合金铁芯有着更高的饱和磁感应强度,B_{3500 A/m}=1.611 T。经350 ℃无磁场退火处理后,Fe₈₂Si_3.8B_13.9C_0.3合金铁芯的损耗P_{50 Hz, 1.4 T}=0.360 W/kg,稍高于1K101合金;经330 ℃纵磁退火处理后,Fe₈₂Si_3.8B_13.9C_0.3合金铁芯的损耗P_{50 Hz, 1.4 T}=0.257 W/kg,也高于1K101合金;经350 ℃横磁退火处理后损耗P_{50 Hz, 1.4 T}=0.163 W/kg,低于1K101合金。纵磁退火Fe₈₂Si_3.8B_13.9C_0.3合金铁芯经浸漆固化处理后,磁通密度B_{800 A/m}=1.341 T,比纵磁退火1K101合金浸漆固化铁芯高15%;纵磁退火且浸漆的Fe₈₂Si_3.8B_13.9C_0.3合金铁芯损耗低于1K101合金浸漆铁芯,且随着频率升高优势更加明显;当频率大于1000 Hz时,纵磁退火且浸漆的Fe₈₂Si_3.8B_13.9C_0.3合金铁芯的损耗值低于未浸漆铁芯。     

Fabrication of Ni34.1Fe27.9B18Si18Nb2 amorphous matrix coating on mild steel by laser processing

Ni34.1Fe27.9B18Si18Nb2 coating was deposited on mild steel substrate using high power laser cladding followed by laser remelting process.The laser processing was conducted by the powder feeding method using low purity materials without shielding box.To learn the surface amorphous matrix coating forming mechanism,the coating without remelting process was also studied.The phases and microstructures were analyzed by X-ray diffraction (XRD),scanning-and transmission-electron microscopy(SEM,TEM).The microhardncss and corrosion resistance property of the coating were also measured.The results of SEM,XRD and TEM analysis show that the remelted coating has an amorphous matrix layer embedded with some crystals due to high cooling rate during remelting process.The crystals phases are identified as Fe2B phase,γ(Fe,Ni)phase and α-Fe phase.No oxidation phases are found in the coating surface.Hardness profiles reveal microhardness more than 1100 HV0.5over the full depth of the amorphous matrix layer,while the unrerntled coating and the substrate show relatively lower hardness than the remelted layer.Corrosion resistance tests exhibit that the remelted coating is nobler than the unremelted coating and the substrate material.     

Effect of Ni content on cracking susceptibility and microstructure of laser-clad FeCrNiBSi alloy

An investigation is reported of the laser surface cladding of self-fluxing Fe---Cr---Ni---B---Si alloys on a medium carbon steel substrate using the preplaced powder method. The cracking susceptibility and microstructure of the laser-cladding layer have been studied in terms of its Ni content, thermal expansion coefficient and wettability on the substrate. With increasing Ni content the cracking susceptibility of the cladding layer decreases and its microstructure changes from a “bamboo leaf” structure to a typical dendritic one.     

Thermally induced crystallization of Fe73.5Cu1Nb3Si15.5B7 amorphous alloy

Thermally induced crystallization of Fe_73.5Cu₁Nb₃Si_15.5B₇ amorphous alloy occurs in two well-separated stages: the first, around 475 °C, corresponds to formation of α-Fe(Si)/Fe₃Si and Fe₂B phases from the amorphous matrix, while the second, around 625 °C, corresponds to formation of Fe₁₆Nb₆Si₇ and Fe₂Si phases out of the already formed α-Fe(Si)/Fe₃Si phase. Mössbauer spectroscopy suggests that the initial crystallization occurs through formation of several intermediate phases leading to the formation of stable α-Fe(Si)/Fe₃Si and Fe₂B phases, as well as formation of smaller amounts of Fe₁₆Nb₆Si₇ phase. X-ray diffraction (XRD) and electron microscopy suggest that the presence of Cu and Nb, as well as relatively high Si content in the as-prepared alloy causes inhibition of crystal growth at annealing temperatures below 625 °C, meaning that coalescence of smaller crystalline grains is the principal mechanism of crystal growth at higher annealing temperatures. The second stage of crystallization, at higher temperatures, is characterized by appearance of Fe₂Si phase and a significant increase in phase content of Fe₁₆Nb₆Si₇ phase. Kinetic and thermodynamic parameters for individual steps of crystallization suggest that the steps which occur in the same temperature region share some similarities in mechanism. This is further supported by investigation of dimensionality of crystal growth of individual phases, using both Matusita–Sakka method of analysis of DSC data and texture analysis using XRD data.     

Effect of preannealing on crystallization process of amorphous Sm5Fe80Cu1Si5B3C2.5Zr3.5 alloy

In the view of crystallization activation energy of amorphous alloy,the mechanism of coarse grain in annealed Sm5Fe80Cu1Si5B3C2.5ZR3.5 amorphous alloy was analyzed.It reveals the e4ffect of preannealing on the process crystallization.The results show that preannealing can be used to change the crystallization behavior of the α-Fe phase in the Sm5Fe80Cu1Si5B3C2.5Zr3.5 amorphous alloy,whick is helpful for forming α-Fe phase grains;and it is not large for Sm2Fe17Cx phase.