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磁控窄间隙TIG焊接技术能有效解决厚板钛合金侧壁熔合不良的问题,其工艺稳定性好、设备成本较低,能为大型钛合金海工结构和装备制造提供有力支撑。围绕厚板钛合金磁控窄间隙TIG焊接技术及其研究现状展开论述。重点阐述了外加横向磁场对电弧摆动的作用机理,并讨论了主要焊接工艺参数(窄间隙坡口设计、焊接电流强度、外加磁场强度和频率及电极位置)对焊缝成形的影响。结合自研结果探讨了不同规格钛合金磁控窄间隙TIG焊接接头的显微组织和力学性能,并进一步概述了焊后残余应力分布特征。研究结果表明,利用外加磁场实现电弧周期摆动能有效调控热输入分布,进而改善侧壁熔合不良的问题;相比其他窄间隙焊接技术,磁控窄间隙TIG焊接能获得更加均匀的焊缝组织和优异的接头力学性能;磁控窄间隙TIG焊接后,接头表面存在较大拉应力,结合合适的热处理工艺能有效降低接头残余应力。最后,对磁控窄间隙TIG焊技术发展和前景进行了展望。 相似文献
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《Materials Science & Technology》2013,29(1):5-19
AbstractThe processing, structures and phase constitutions and the magnetic properties of nanocomposite hard magnetic alloys are reviewed. The emphasis is on rare earth (RE)–iron–boron alloys in which the hard magnetic phase RE2Fe14B is intermixed with one or more soft magnetic phases. Processing–structure–property relationships are the principal focus, in particular, the role of the hard and soft nanocrystallite dimensions in promoting intergrain ferromagnetic exchange coupling and the consequent enhancement of remanent magnetisation and the technologically important maximum energy density. The powder processing, chill block melt spinning, mechanical alloying and thin film deposition routes to develop nanocrystalline and nanocomposite structures are reviewed. The coercivity mechanism in ultrafine grained alloys and the influence of crystallite dimensions are discussed, as are the effects on intrinsic and extrinsic properties of RE substitutions, replacement of iron by other transition metals and enrichment of the boron content. Exchange enhancements in Sm–Co based nanocomposite bulk alloys and in nanoscale FePt/α-Fe composite thin films are briefly considered, together with thin film materials involving exchange coupling between ferromagnetic and antiferromagnetic phases, in core–shell type structures of transition metal compounds surrounded by oxides and in mechanically alloyed materials. The processing and magnetic properties of bonded magnets based on nanocrystalline/nanocomposite REFeB alloys are discussed. The possibility of producing anisotropic hard/soft composites with properties approaching the theoretical maximum is considered and the extent to which this goal has been realised for fully dense alloys identified. 相似文献
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Bi-Mn合金研究进展 总被引:2,自引:0,他引:2
MnBi相具有显著的铁磁性及磁光效应,可用作永磁和磁光存储材料.对Bi-Mn合金进行掺杂可改善合金的性能.一些新的Bi-Mn化合物表现出诱人的特性,如巨磁阻效应、铁电效应等.用外加电场或磁场可影响合金的凝固组织和性能.综述了这几方面的最新研究进展. 相似文献
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Soft magnetic alloys that are now in practical use or under development in Japan are reviewed. In the field of Si-Fe alloys, the influence of various processing parameters, such as addition of elements, heat treatments, and alloy composition on the mechanical and the magnetic properties and recent developments in methods of measuring iron losses are described and discussed. As for Ni-Fe alloys, the effects of refining reagents or added elements adjusting the formation of the superlattice Ni3 Fe on the magnetic properties are given. Finally systematic studies on the relation between degree of order and magnetic properties of Ni-Mn alloys are reviewed. 相似文献
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R. A. Hein H. Hojaji A. Barkatt H. Shafii K. A. Michael A. N. Thorpe M. F. Ware S. Alterescu 《Journal of Superconductivity》1989,2(4):427-461
A comparison of the low magnetic field properties of sintered (990°C) and partially melted samples (1050°C) has been performed. Changes in the microstructure produced by recrystallization from the melt result in a significant increase in flux pinning at 77 K. Low-frequency (10–100 Hz), low-a.c. magnetic field (0.01–9.0 Oe) a.c. susceptibility data show that gross changes in the a.c. loss component accompanies the observed changes in microstructure. The effects of applied d.c. magnetic fields (10–220 Oe) on the a.c. responses of these microstructures have also been probed. Data are analyzed and critically discussed in terms of current models appropriate for granular superconductors and in terms of older models appropriate for metallic alloys and compounds. Particular attention is given to published interpretations of the in-phase or loss component of the a.c. magnetic susceptibility and to the possible roles which minority phases and sample inhomogeneities may play in determining the detailed a.c. responses of these high-T
coxides. 相似文献
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近年来,高熵合金成为金属材料领域的研究热点。高熵合金处于相图中心区域,具有广阔的合金成分空间和组织结构形成可能;成分和制备工艺的协同调控,能够获得更丰富的组织结构;非常规的化学结构有望突破传统抗磨、润滑合金的性能极限。本文讨论了耐磨高熵合金的分类,分析了化学活泼金属、软金属、难熔金属的添加对高熵合金抗磨、润滑性能的影响规律;总结了非金属元素和陶瓷相的添加对高熵合金基复合材料摩擦磨损性能的影响;综述了热处理和表面工程技术对高熵合金表面组织结构和摩擦磨损行为的作用;讨论了苛刻工况下抗磨润滑高熵合金的设计方法。对未来高熵合金在摩擦磨损领域的研究和应用进行了展望,高熵合金在解决传统合金的瓶颈问题上具有巨大潜力,如在极端工况下实现稳定润滑抗磨、保证特定功能作用下实现抗磨。 相似文献
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Structural nanocrystalline materials: an overview 总被引:1,自引:0,他引:1
Carl C. Koch 《Journal of Materials Science》2007,42(5):1403-1414
This paper presents a brief overview of the field of structural nanocrystalline materials. These are materials in either bulk,
coating, or thin film form whose function is for structural applications. The major processing methods for production of bulk
nanocrystalline materials are reviewed. These methods include inert gas condensation, chemical reaction methods, electrodeposition,
mechanical attrition, and severe plastic deformation. The stability of the nanocrystalline microstructure is discussed in
terms of strategies for retardation of grain growth. Selected mechanical properties of nanocrystalline materials are described;
specifically strength and ductility. Corrosion resistance is briefly addressed. Examples of present or potential applications
for structural nanocrystalline materials are given. 相似文献
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Anisotropic magnetoresistance in ferromagnetic 3d alloys 总被引:9,自引:0,他引:9
The anisotropic magnetoresistance effect in 3d transition metals and alloys is reviewed. This effect, found in ferromagnets, depends on the orientation of the magnetization with respect to the electric current direction in the material. At room temperature, the anisotropic resistance in alloys of Ni-Fe and Ni-Co can be greater than 5%. The theoretical basis takes into account spin orbit coupling and d band splitting. Other properties such as permeability, magnetostriction, and Hall voltage have no simple relationship to magnetoresistance. Anisotropic magnetoresistance has an important use as a magnetic field detector for digital recording and magnetic bubbles. Such detectors because of their small size are fabricated using thin film technology. Film studies show that thickness, grain size, and deposition parameters play a significant role in determining the percentage change in magnetoresistance. In general, the change is smaller in films than bulk materials. Several tables and graphs that list bulk and film data are presented. 相似文献
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磁场烧结在材料制备中的应用 总被引:1,自引:0,他引:1
综述了近年来磁场烧结在材料制备中的应用情况,重点分析了磁场烧结对烧结动力学、材料组织结构等方面的影响,简要介绍了磁场烧结在超导材料制备中的应用。 相似文献
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《Materials Science & Technology》2013,29(9):772-781
AbstractAircraft gas turbines contain various sheet metal fabrications, such as combustion chambers, exhaust units, jet pipes, and reheat liners, which operate for long periods under arduous conditions. The properties required in a sheet alloy differ considerably from those of blades and vanes, so that alloys must be developed specifically for the purpose. The performance required of sheet alloys is discussed and current alloys are reviewed in terms of their fabrication, mechanical, and oxidation properties. Some recent developments are described in the field of thermal barrier coatings, dispersion strengthened alloys, and porous laminate materials.MST/524 相似文献
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L. F. Cohen A. Cowie J. C. Gallop I. S. Ghosh I. N. Goncharov 《Journal of Superconductivity and Novel Magnetism》1997,10(2):85-90
Using a 5-GHz parallel-plate resonator, several Gd 123 films and one Tl 2212 film have been studied as a function of microwave
power. The variation of the surface resistance as a function of dc magnetic fields applied parallel to the crystallographicc axis reflects the gross microstructure of the films. Two broad categories of behavior are observed in dc field. The evidence
for intrinsically limited power dependence is discussed in terms of impedance plane analysis. 相似文献
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磁驱动形状记忆合金是一种新型功能材料,由于兼具大的输出应变和高响应频率等综合特性,成为智能材料领域的研究热点之一.本研究首先总结了Ni-Mn-Ga合金在相变和磁致应变性能方面的特点,然后着重介绍了Co-Ni-Ga和Ni-Fe-Ga两类新型磁驱动记忆合金在结构、相变、形状记忆效应、磁性能等方面的研究进展,并对其中存在的问题进行了讨论. 相似文献
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软磁材料是一种极为重要且应用十分广泛的能源材料,近年来,随着磁性元件的日益高频化和小型化,以及节能环保的号召,开发和研究高性能软磁材料具有重要意义。本工作概述了软磁合金的发展历史,重点归纳出各类软磁合金(包括传统软磁合金、非晶/纳米晶软磁合金、高熵软磁合金)的成分、微观组织、磁性能以及应用范围,并总结出不同软磁合金的优、缺点;指出典型合金的微观组织对合金软磁性能(尤其矫顽力)具有关键性的主导作用,进而探讨了影响软磁合金矫顽力的因素及其微观机制,发现控制晶粒尺寸(或纳米粒子尺寸)是获得低矫顽力的关键,并描述了矫顽力的微观影响机制在高熵软磁合金中的发展;最后,展望了高熵软磁合金因多主元混合的成分特性带来的组织多样化,更有利于实现对合金性能的调控,并有望作为新一代高温软磁体材料。 相似文献
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Magnetostrictive phenomena in metallic materials and some of their device applications 总被引:1,自引:0,他引:1
The phenomenon of magnetostriction, or the change in a body's dimensions during the magnetization process, was first reported by Joule. Since then, the interaction between strain and the magnetization process has been studied extensively, particularly in the magnetic metals and alloys that have been found to be of technological importance. The purpose of this paper is to review magnetostrictive phenomena in metallic materials and to discuss a number of devices making use of magnetostriction. After presenting some fundamentals of magnetostriction, a review is given of magnetoelastic effects and magnetoelastically induced anisotropies in magnetic films. Some of the domain patterns and domain visualization techniques that have been found to be related to the magnetostrictive properties of magnetic materials are discussed. The application of magnetostrictive materials to memory devices is reviewed. Included are such areas as magnetostrictive delay lines, ferroacoustic memories of both the flat film and wire type, thermo-strictive recording, and fiat film displays and display memories. 相似文献
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本文叙述了国内外镁合金稀土元素合金化的研究进展;讨论了稀土元素对镁合金熔体、组织和性能以及耐腐蚀性的影响;分析了镁稀土合金研究存在的问题;指出镁稀土合金是镁合金研究的重要发展方向。 相似文献