H Y Jing
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L.X. Huo and Y. F. Zhang(Tianjin University
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Tianjin 300072
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China)F. Mnami(Osaka Univeristy
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Osaka
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Japan)
金属学报(英文版)
A 3-D computationalframework was suggested to model stable growth of a macroscopic crack under model I condition. The Gurson-Tverpaaof dilatant plasticity model for voided materials describes the damage process. Fixed-sized, computational cell elements (containing voids) defined over a thin layer at the cmck plane simulate the ductile crack extension. Outside of this layer, the material remains undamaged by the void growth. The micro-mechanics parumeters controlling cmck growth are the thickness Of computational cell layen D, and the initial void porosity, fo. These parameters are calculated through analyses of ductile tearing to match R-curve obtained from testing of deep notch bend specimens for welded joints. The R-curve for the double edge notched tension specimens is eNctively predicted using these pammeters.The predicted R-curve gives a good agreement with the expemment results.
关键词:
ductile crack growth
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Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
Superconductor Science & Technology
It is shown that the superconductivity in Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds can be modulated by internal (chemical) pressure. The internal pressure is induced by Gd substitution for Ce in CeFeAsO(0.84)F(0.16), which compresses the crystal lattice. The temperature dependences of resistivity and magnetization show that the superconducting-transition temperature T(c) is enhanced from 40 K for CeFeAsO(0.84)F(0.16) to 47.5 K for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16). The increase and subsequent decrease of Tc upon application of external pressure, as observed previously in LaFeAsO(0.89)F(0.11), is entirely confirmed by the modulation of Tc of the Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by internal pressure.
关键词:
layered quaternary compound;43 k;iron
Applied Physics Letters
The effect of nonmagnetic Y partial substitution at the Dy site in Dy(1-x)Y(x)MnO(3) up to x=0.2 on magnetism, specific heat, and ferroelectricity is investigated, which resulted in a preliminary multiferroic phase diagram. It is revealed that the Y partial substitution suppresses the Dy-spin ordering point (T(Dy)) and ferroelectric ordering point (T(FE)) but enhances the Mn-spin ordering point (T(N)). The interaction between the spins of Dy and Mn is remarkably affected by Y substitution. The measured electrical polarization depends on the Y substitution in a complex way because the ferroelectricity is sensitive to the interaction between the spins of Dy and Mn. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3536506]
关键词:
ferroelectricity;polarization
Journal of Applied Physics
Structural parameters have a critical impact on superconductivity in iron-based oxypnictide superconductors. Structural evolution study was performed on Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by the analysis of the x-ray diffraction patterns with Rietveld refinement. Substitution of Gd for Ce generates internal pressure that compresses the crystal lattice. The contraction of the c axis is also indicated by the reduction of Ce/Gd-As and Ce/Gd-O/F distances, while there is a slight increase in the As-Fe-As block size, which is compensated by a large reduction in the Ce/Gd-O/F-Ce/Gd block with Gd substitution. The diagonal Fe-As-Fe angle for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16), with the highest T(c) among Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds, is 111.13 degrees. It is close to the ideal value of 109.47 degrees for the perfect FeAs tetrahedron, which is situated in the region of Fe-As-Fe bond angles where RFeAsO compounds tend to have the highest T(c). (C) 2011 American Institute of Physics. [doi:10.1063/1.3565408]
关键词:
layered quaternary compound;high-temperature superconductivity
崔雅静
,
陈永亮
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杨烨
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王雅真
,
张勇
,
赵勇
低温物理学报
通过先制备一种纳米尺寸的GdF_3作为GdFeAsO_(1-x)F_x样品中F的反应原料,在相对较低的温度(1120℃)下成功制备出一系列GdFeAsO_(1-x)F_x(x=0,0.05,0.1,0.15,0.2,0.25)多晶样品.X射线衍射结果表明,超导样品属四方ZrCuSiAs-type结构,晶格参数随着掺F量的增加而减小.扫描电子显微镜测试结果表明,样品具有片层状晶体形貌特征.当掺F量x=0.1时,样品表现出超导电性,超导转变温度为22K,随着掺F量的增多,超导转变温度升高.和其他制备方法相比,这种制备方法更有利于F的掺入,而且可有效减少样品中杂质相的含量.
关键词:
铁基超导体
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ZrCuSiAs结构
X. Chang
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K. Qin and Y.L.Lu Orthodontic Department of Stomatology College
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China Medical University
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Sheny ang 110001
,
China
金属学报(英文版)
proach change of CGRP with time in periodontal ligaments of rats in magnetic field, maxillae of 28 Wistar rats of 6 7 weeks were placed in magnetic fields of permanent magnets Nd 2 Fe 4 B. Changes of CGRP with t ime in maxillary periodontal ligaments of the rats were studied by immunohistochemistry. The result showed that: magnetic field had dynamic effect and some promotional effect on recove?E F F E C T O F M A G N E T I C F I E L D O N C A L C I T O N I N G E N E- R E L A T E D P E P T I D E I N P E R I O D O N T A L L I G A M E N T S O F R A T S X. Chang , K. Qin and Y. L. Lu Orthodontic Department of Stomatology College , China Medical University , Shenyang 110001 , China Manuscript received 24 June 1999 In order to approach change of C G R P with tim e in periodontal liga m ents of rats in m agneticfield , m axillae of 28 Wistar rats of 6 7 weeks w ere placed in m agnetic fields of per m anentm agnets Nd 2 Fe4 B. Changes of C G R P with tim e in m axillary periodontal liga ments of therats were stu died by i m m unohistoche mistry . The result sho wed that : m agnetic field had dy na m ic effect an d so m e pro motional effect on recovering and reconstruction of the periodontaltissues in it . This provided a better theoretical evidence for clinical use of per m anent m agnets .
关键词:
per m anent m agnet Nd 2 Fe4 B
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