Co基纳米晶软磁合金研究进展

本文对钴基非晶合金的晶化及其磁性研究的进展进行了综述,内容包括：（1）零磁致伸缩Co基非晶合金的晶化行为;（2）Vitrovac 6025型合金的纳米晶化和磁性;（3）bcc结构的Co-Fe-Nb-Si-B纳米晶合金的研究。对有关晶化产物及磁性的问题进行了讨论。     

Fe－Zr－B－Cu非晶合金的纳米晶化和低频软磁特性

Ｆｅ－Ｚｒ－Ｂ－Ｃｕ非晶合金的纳米晶化和低频软磁特性Ｆｅ－Ｚｒ－Ｂ－Ｃｕ合金是迄今报告的具有最高饱和磁感的纳米晶合金。日本川崎钢铁公司最近研究了这种非晶材料的纳米晶化特点、低频软磁特性以及铁芯损耗与晶粒尺寸的关系。实验的合金为Ｆｅ８６ＺｒｘＢ１３－ｘ...     

非晶纳米晶软磁合金的研究进展

介绍了非晶纳米晶软磁合金的最新研究进展,简要分析和总结了添加合金元素以及晶化退火工艺对非晶纳米晶合金结构和性能的影响.最后,根据现有非晶纳米晶合金的研究现状以及实际应用中对其性能的要求,指出了未来非晶纳米晶软磁合金的发展方向.     

高能球磨Ti55.5Cu18.5Ni17.5Al8.5合金非晶化研究

采用机械合金化(MA)制备出Ti_(55.5)Cu_(18.5)Ni_(17.5)Al_(8.5)非晶粉末。利用X射线衍射仪(XRD)、示差扫描量热分析仪、扫描电镜、透射电镜等研究了不同球磨时间粉末的微观形貌以及非晶化行为,探讨了非晶化对合金硬度的影响。结果表明,首先随着球磨时间的增加,微观组织的演变规律是合金晶粒逐渐变小,出现纳米晶化合物;随后纳米晶化合物内部发生局部结构长程无序化,纳米晶化合物分割成更为细小的纳米晶;最终纳米晶颗粒完全非晶化。从原子尺度证明了非晶化的主要原因是高能球磨过程中发生了剧烈塑性变形,形成了高密度位错以及严重的晶格畸变,最终导致原子长程无序化从而形成非晶。球磨引起加工硬化和非晶晶化,使得球磨后的合金粉末硬度显著增加。     

初生纳米晶对Ti40Zr25Ni8Cu9Be18非晶合金结构稳定性的影响

通过感应熔炼喷铸法制备具有非晶/纳米晶复合结构的块体Ti40Zr25Ni8Cu9Be18合金。在与全非晶结构的Ti40Zr25Ni8Cu9Be18合金进行比较的基础上,研究Ti40Zr25Ni8Cu9Be18非晶/纳米晶合金在均匀流变过程中的晶化程度,分析其在连续升温过程中的晶化动力学。结果表明:初始纳米晶的存在不会明显降低非晶/纳米晶合金在过冷液相区流变过程中的结构稳定性;非晶/纳米晶合金的晶化激活能约为233.21 kJ/mol,与非晶合金的晶化激活能大致相同;随着转变分数的增加非晶/纳米晶合金的局部Avrami指数从2变化到0.5,明显低于非晶合金的局部Avrami指数;这表明初始纳米晶并没有明显加速非晶的晶化过程。     

纳米晶材料发展趋势

纳米晶材料发展趋势非晶金属磁性材料主要包括铁基和钴基两大类，前者具有很高的饱和磁通密度（ＢＳ），但有磁致伸缩不易减小到零和很难得到很大磁导率（μ）等缺点；然而后者则具有很大的卜，但ＢＳ却较小。纳米晶合金则综合了铁基与钻基非晶合金两者的优点，因为纳米晶...     

非晶合金炉内退火和通电退火纳米晶化的比较

对于一些含Ｃｕ的和含Ｎｂ的铁基非晶合金晶化热处理时 ,通过控制部分晶化过程可获得超细晶组织 (纳米晶 )。这种纳米晶合金的特点 ,是具有优越的软磁性 ,亦即具有很高的饱和磁化强度和低的矫顽力。铁 类金属非晶合金通常采取 50 0～ 6 0 0℃退火即可实现部分晶化。这类非晶合金之所以形成纳米晶相 ,往往与合金中有少量铌和铜的存在有关 :铜实际上不与铁混溶会形成局域原子丛聚 ,从而促成了纳米晶组织的形核 ;加铌会使剩余非晶相稳定化并阻止晶粒长大。印度和意大利的研究者比较研究了ＦｅＣｕＮｂＳｉＢ非晶合金采取炉内退火和通电退火对其…     

加镍对非晶Fe78B13Si9低温破碎研磨的影响

ＭｅｔｇｌａｓＦｅ78Ｂ13Ｓｉ9非晶合金借助于高能球磨机械晶化可用来制取纳米晶材料。早在 90年代初就有人研究了在这种非晶合金中添加Ｎｉ、Ｃｏ、Ｃｕ、Ｎｂ、Ａｌ进行球磨时的晶化效果。美国加里福尼亚大学的化学工程与材料科学系的科研人员 ,研究了在Ｆｅ78Ｂ13Ｓｉ9非晶带材进行高能球磨时添加元素镍对于非晶纳米晶化的效果。研究用的非晶ＭｅｔｇｌａｓＦｅ78Ｂ13Ｓｉ9带材是由美国ＡｌｌｉｅｄＭｅｔｇｌａｓＰｒｏｄｕｃｔｓ公司提供的 ,元素镍粉 (纯度为99 9% ,粒度为 4 5 μｍ)由Ｃｅｒａｃ公司生产的。按ＭｅｔｇｌａｓＦｅ78…     

高强脉冲电流工艺参数对Fe基非晶合金纳米晶化的影响

高强脉冲电流能使Fe基非晶合金在低于非晶转变温度70～100K的条件下实现快速晶化。脉冲频率和处理时间对Fe基非晶合金晶化过程有显著影响。在高强脉冲电流的作用下,随着处理时间的增加,Fe基非晶合金先发生结构弛豫,然后在某一临界处理时间之后发生快速晶化,析出大量的α-Fe(Si)纳米相,最后晶化过程趋于稳定。提高脉冲频率f,可以有效缩短临界处理时间,但不改变Fe基非晶合金纳米晶化过程中显微硬度的变化趋势。与等温退火工艺相比,高强脉冲电流处理是一种高效的非晶合金快速晶化方法。     

用于制备贴片电感的铁基非晶软磁合金的晶化过程研究

本研究用软磁性能优良的铁基非晶软磁合金作为贴片电感的磁芯材料,通过XRD、TEM等分析测试研究了Fe73.5Cu1Nb3Si13.5B9 非晶软磁合金的热处理纳米晶化过程中的结构和组织形貌变化.结果证明:铁基非晶软磁Fe73.5Cu1Nb3Si13.5B9合金的晶化过程主要发生在500℃之后,当退火温度在520～600℃时,纳米晶粒晶化充分且分布较为均匀,使材料具有较好的软磁性能,这为贴片电感的制备莫定了基础.     

Atomic simulation on evolution of nano-crystallizaion in amorphous metals

The deformation-induced nano-crystallization behavior of amorphous pure Ni was investigated by using a molecular dynamics simulation. The microevolution mechanism of the nano-crystallization, the crystallization process in the multicomponent amorphous Ni-Pd alloys and the temperature effect on the nano-crystallization behavior in amorphous metals were studied. The results show that the small nano-crystalline grain will nucleate and grow during the compression deformation. The deformation induces the growth of the ordered clusters in the amorphous metals and the nano-crystalline grain grows under the shearing combination and sheafing deposition. The nano-crystalline grain will nucleate in a lower strain under a higher temperature. The combining severe plastic deformation with thermal annealing treatments presents a new opportunity for developing bulk nano-crystalline materials with controlled microstructures.     

Non-isothermal nano-crystallization kinetics in amorphous Ni55Nb35Si10 alloy

The non-isothermal crystallization kinetics of Ni₅₅Nb₃₅Si₁₀ amorphous alloy, prepared by mechanical alloying, was studied using differential scanning calorimetry. The amorphous alloy showed one-stage crystallization on heating, which led to the formation of nano-intermetallic crystals in amorphous matrix. The apparent activation energy for the crystallization of the alloy, determined by the Kissinger equation, was relatively high (468 kJ/mol), indicating that this amorphous alloy has high thermal stability. Changes in the activation energy during the crystallization process, were also evaluated by iso-conversional methods. The results showed that it decreases slowly from the beginning to crystallized fraction α=0.35 and it remains almost constant to the end of the process. The nano-crystallization mechanism for the non-isothermal crystallization of the amorphous alloy was explained by determining Avrami exponents. Transmission electron microscopy studies revealed the microstructural modification of amorphous alloy via nano-crystallization during annealing. The results suggest that the nucleation rate decreases with increasing time and the crystallization mechanism is governed dominantly by a three-dimensional diffusion-controlled growth. A predictive equation was obtained based on the Sestak?Berggren autocatalytic model to describe quantitatively the non-isothermal crystallization kinetics.     

Fe-Al金属间化合物研究概况与发展方向

本文系统阐述了Fe-Al金属间化合物的室温脆性本质和用热加工处理、合金化等传统工艺提高其室温塑性的研究成果,以及Fe-Al金属间化合物纳米化增塑的最新研究进展,并详细介绍了Fe-Al金属间化合物作为高温耐磨耐蚀涂层和高温气体净化多孔材料的研究新动向。     

Multi-phase nanocrystallization induced fast degradation of methyl orange by annealing Fe-based amorphous ribbons

Different from the common understanding that crystallization deteriorates the degradation capability of amorphous alloys, we show here that the Fe-based multi-phase nanocrystalline ribbons (Fe-MNRs) exhibit 3 and 17 times higher degradation rate than its amorphous counterpart and the conventional zero valent iron powders, respectively. The formation of multi-phase nanocrystals and nanoporous structure resulted from selective corrosion during degradation is responsible for the high degradation capability of Fe-MNRs. The present results suggest that suitable nano-crystallization annealing treatment could be a novel approach to enhance the degradation capability of Fe-based amorphous alloys.     

金属材料表面自纳米化及其研究现状

综述了材料表面自纳米化的国内外研究现状,包括表层自纳米化的一些常用研究方法及机理,表层纳米化层的组织结构及其对材料力学性能的影响,表面自纳米化技术的应用前景.     

40 Cr 钢表面高能喷丸纳米化及其耐磨性能

为了研究40Cr钢表面纳米化对其耐磨性能的影响,对40Cr钢表面进行高能喷丸处理,获得纳米结构表层,分析了材料表面高能喷丸前后的微观组织变化,测定了纳米化材料表层的残余应力及显微硬度,研究了纳米化表层的磨损性能。结果表明:高能喷丸使40Cr钢表层发生了严重塑性变形,显微硬度较基体提高了68%,并使材料表面分布了较高幅值残余压应力,最大可达-736 MPa,残余压应力层深度达0.9 mm;高能喷丸表面纳米化能在一定程度上降低40Cr钢表面的摩擦系数,且大大减小其磨损失重,显著改善了40Cr钢的耐磨性能。     

A TEM study on the crystallization behavior of an yttrium-doped Zr-based bulk metallic glass

Transmission electron microscopy (TEM) is used to conduct the systematic study of the annealing induced crystallization, both continuously and isothermally, of a Zr-based metallic glass. Through detailed microstructure analysis, it is found that the crystallization of this metallic glass is initialized by a nano-scaled primary crystallization process with a tetragonal structured crystal (a = 0.96 nm and c = 2.82 nm) as the primary phase. A eutectic crystallization is followed afterwards with two types of crystalline phases as the crystallization products, one of which is determined to be a metastable orthorhombic phase (a = 0.69 nm, b = 0.75 nm and c = 0.74 nm). Upon annealing at a raised temperature or isothermal treatments, a solid state phase transformation takes place and the orthorhombic metastable phase transforms into two types of tetragonal crystalline phases. The whole crystallization process of this metallic glass is in turn realized, and the thermal stability and nano-crystallization mechanism are discussed based on the microstructure and thermal analyses.     

非晶材料压缩变形中纳米晶化现象的分子动力学模拟

利用分子动力学方法对非晶纯镍材料压缩变形过程中纳米晶化现象进行了模拟，研究了非晶变形过程中绝热温升对非晶晶化的影响，结果表明，绝热温升不是导致非晶晶化的主要因素．从微观结构演化的角度考察了非晶晶化过程中晶粒的形核和长大，分析发现，应变导致非晶态金属从亚稳态结构逐渐向稳态结构转变，在系统内部的部分短程序原子团逐步合并形成小的晶核，随着应变的增加，晶核逐渐长大，形成一定尺寸的纳米晶粒．     

Zr-Ce-SBA-15介孔材料的合成和形貌调控

以正硅酸乙酯(TEOS)为硅源,P123为模板剂,氯化氧锆(ZrOCl2·8H2O)和硝酸亚铈(Ce(NO3)3·6H2O)为锆、铈前驱体,在不外加无机酸的条件下,利用无机前驱盐自身水解产生的弱酸性环境,水热法一步合成Zr-Ce-SBA-15介孔材料。通过改变起始物料配比和调节合成温度可以实现对产物的形貌进行有效控制。利用小角X射线衍射(LXRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、电感耦合等离子体原子发射光谱(ICP-AES)和氮气吸附等手段对所合成的样品进行了表征。结果表明:在nZr(Ce):nSi物质量的比分别为0.03,0.05,0.10时,合成的材料具有类似于SBA-15高度有序的二维六方相介孔结构,锆、铈物种被成功引入SBA-15材料的骨架中。当nZr(Ce):nSi摩尔比为0.05,晶化温度为100℃时,Zr-Ce-SBA-15表现为六方板状形貌。随着晶化温度的升高,Zr-Ce-SBA-15的形貌由六方板状转变成圆盘状。     

Carburizer Effect on Cast Iron Solidification

This paper presents the effect of carburizing materials on cast iron solidification and crystallization. The studies consisted of cast iron preparation from steel scrap and different carburizers. For a comparison, pig iron was exclusively used in a solid charge. Crystallization analysis revealed the influence of the carburizer material on the crystallization curves as well as differences in the solidification paths of cast iron prepared with the use of different charge materials. The carburizers’ influence on undercooling during the eutectic crystallization process was analyzed. The lowest undercooling rate was recorded for the melt with pig iron, then for synthetic graphite, natural graphite, anthracite, and petroleum coke (the highest undercooling rate). So a hypothesis was formulated that eutectic cells are created most effectively with the presence of carbon from pig iron (the highest nucleation potential), and then for the graphite materials (crystallographic similarity with the carbon precipitation in the cast iron). The most difficult eutectic crystallization is for anthracite and petroleum coke (higher undercooling is necessary). This knowledge can be crucial when the foundry plant is going to change the solid charge composition replacing the pig iron by steel scrap and the recarburization process.