共查询到19条相似文献,搜索用时 61 毫秒
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FeCuNbBSi等多中Fe基非晶态合金激波晶化的DSC研究 总被引:1,自引:0,他引:1
应用升温、等温和重复加热的DSC技术,对几种非晶合金的激波晶化和退化晶化作了对比研究,结果表明,尽管激波晶化时间极短,仅为退火晶化时间为10^-6--10^-8,但晶化度却极高,接近100%。激波晶化形成多种成分和结构的结晶相,形式上很像扩散性相变,然而其相变速率却是退火转变的千万倍,而且生成相十分稳定,这一现象用传统的固态扩散相变理论很难解释,激波晶化是一种新的晶化形式,是一种新的纳米合成技术。 相似文献
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根据用原子力显微镜对在不同温度下晶化的Fe基非晶合金薄带三维介观结构的观察,结合X射线衍射、Mssbauer谱等前人已有的实验结果并在目前已有的理论研究基础上,对Fe基非晶合金薄带在不同温度下的晶化过程进行了系统的分析、研究,提出了两种Nb-B框架介观结构、团聚相和单位体积纳米晶粒平均数等新概念,建立了Fe基纳米晶合金的晶化机理假说,提出了描述Fe基非晶合金晶化过程的介观织构模型.这个模型能够演化成二相结构模型和三相互套结构模型,还可以合理地解释现有的实验结果以及500—600℃退火中Fe基纳米晶巨磁阻
关键词:
Fe基纳米晶合金
晶化机理
两种Nb-B框架介观结构
团聚相 相似文献
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从非晶态合金的晶化出发,介绍了最近发展起来的新型优质软磁材料──纳米晶软磁合金.其中包含:(1)非晶态合金的晶化概念以及微晶析出对非晶态合金磁性的影响;(2)纳米晶软磁材料的发现及其具有的优良的综合磁性能;(3)分析了该合金优良磁性能的来源,介绍了目前理论上的解释.最后展望了该合金的发展趋势. 相似文献
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Shanglong Peng Na Feng Duokai Hu Deyan He Chang-Woo Byun Yong Woo Lee Seung-Ki Joo 《Current Applied Physics》2012,12(6):1470-1475
Intrinsic and doped polycrystalline silicon thin films were grown by the Ni silicide seeds induced crystallization. The Ni first reacted to Si forming a silicide seeds, then these seeds act as nuclei, from which the grains start to grow laterally. Compared with traditional Ni induced lateral crystallization, polycrystalline silicon thin film was grown by Ni silicide induced crystallization with low Ni contamination and large grain sizes. It can be found that the Ni silicide induced crystallization rate is accelerated by p-type doping and is decelerated by n-type doping. And the slightly and strongly phosphorous-doped polycrystalline silicon can be obtained with different grain shapes. Also, the sheet resistance of doped polycrystalline silicon decreases with the increasing of the doping atoms. A reasonable explanation is presented for the dopant effects on the growth rate, microstructure and electronic properties of the samples. 相似文献
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J. Yepez 《Journal of statistical physics》1995,81(1-2):255-294
This paper presents a new lattice-gas method for molecular dynamics modeling. A mean-field treatment is given and is applied to a linear stability analysis. Exact numerical simulations of the solid-phase crystallization are presented, as is a finite-temperature multiphase liquid-gas system. The lattice-gas method, a discrete dynamical method, is therefore capable of representing a variety of collective phenomena in multiple regimes from the hydrodynamic scale down to a molecular dynamics scale. 相似文献
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The arguments leading to the concept of an electron crystal in the low density regime of ‘jellium’ are reviewed. Ground-state properties discussed include estimates of the critical density at which the transition to a crystalline state takes place, and then in the low density regime the dielectric function, pair function and momentum distribution are dealt with. The magnetic character of the ground state as a function of density is also considered. The low-lying excitations of the Wigner electron crystal are phonon-like and hence the low temperature specific heat obeys a T 3 law. Defect models are considered in order to throw further light on the character of excited states. Finally experimental conditions favourable for electron crystallization are briefly considered. 相似文献
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Effects of the molecular and crystal structures of polymerizable substances on their radiation-induced solid-state polymerization are considered for two cases; the solid state polymerization of cyclic oligomers of formaldehyde and the canal polymerization of some monomers. Cyclic oligomers of formaldehyde (–CH2–O–)m from m = 3 to 6 are transformed into three-dimensionally oriented crystalline polyoxymethylene by irradiation. The polymer crystals are characteristically oriented, depending upon the parent oligomer crystal structures. A small amount of an oriented, unstable modification (orthorhombic) polyoxymethylene is also obtained in X-ray in-source polymerization of hexoxane. Highly 1,4-trans tactic polymerization of 2,3-dichloro-1,3-butadiene and 2,3-dimethy1-1,3-butadiene in the thiourea canals is shown by structural evidence, based upon the crystal structure determinations of the monomerthiourea complexes, the polymer-thiourea complexes, and the resultant polymers for both dienes. The conversion of the monomer-thiourea complexes to the polymer-thiourea complexes by irradiation is performed, retaining the original single crystal habit, though in the canals the monomer-monomer distances are shortened by polymerization. The polymer samples obtained from the single crystals of polymer-thiourea complexes by removal of thiourea are uniaxially oriented and have unusual fine structures. 相似文献
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Dan H. Constantinescu 《Physics letters. A》1981,85(1):45-47
The bifurcation of periodic solutions is a necessary, but not a sufficient, condition for electron crystallization. Consequently, the crystallization domain in phase space may be considerably smaller than the bifurcation domain. 相似文献
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In this paper, polymer brushes are studied via molecular-dynamics simulations at very high grafting densities, where the crossover
between the brush regime and the polymer-crystal regime is taking place. This crossover is directly observed with the structure
factor and pair-correlation function. With increasing grafting density, this crystallization is progressing from the core
layer of the brush towards the surface layer. The same process is analyzed using the lateral fluctuations of the monomers
as a signature of their diminishing mobility. Additionally, bond forces and the chain excess free energy indicate a transition
from the brush regime to the overstretched regime, which is in agreement with predictions of a modified self-consistent field
theory. 相似文献
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Properties of an interface, created at some experimental conditions in the course of the equilibrium crystallization process, are theoretically investigated. Influence of quantum and thermal fluctuations on smoothing-roughening phase transitions is considered. The phase diagram illustrating these properties is found. 相似文献