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1.
The effect of Re addition on the microstructure and hardening behaviour of the dual two-phase Ni3Al (L12) and Ni3V (D022) intermetallic alloy was investigated by scanning electron microscopy, transmission electron microscopy and Vickers hardness test. The two-phase eutectoid microstructure accompanying the Re-rich precipitates were observed in the channel region of the alloys in which Re substituted for Ni but not in those in which Re substituted for Al and V. The concomitant addition of Nb (or Ta) with Re more stabilized the two-phase eutectoid microstructure and consequently more induced the fine precipitates in the channel region. The annealing at temperatures below the eutectoid temperature was necessary to induce the fine precipitates in the channel region and thereby result in the precipitation hardening. The fine precipitation in the channel region and related hardening was attributed to the alloying feature so that Re is soluble in the A1 (fcc) phase at high temperatures and becomes less soluble in the two intermetallic phases decomposed from the A1 phase at low temperatures. 相似文献
2.
利用电弧熔炼制备了 (Nd1 xErx) 2 Co1 5 5V1 5(x=0— 1 0 )化合物样品 .通过x射线衍射分析和磁性测量研究了Er替代Nd2 Co1 5 5V1 5中的Nd时对化合物结构和磁性的影响 .研究结果表明 ,低Er含量 (x <0 4 ) ,化合物为Th2 Zn1 7型结构 ;高Er含量时 (x >0 5 ) ,化合物转变为Th2 Ni1 7结构 ;Er含量为x =0 4和 0 5时 ,两种结构共存 .两种结构的晶胞参数a ,c和晶胞体积V随着Er含量的增加都呈现递减的趋势 .随着Er含量的增加 ,(Nd1 xErx) 2 Co1 5 5V1 5化合物的居里温度和饱和磁化强度都单调下降 .(Nd1 xErx) 2 Co1 5 5V1 5化合物的室温各向异性由低Er含量时的易锥型转变为高Er含量时的易轴型 .x =0— 0 5的化合物在温度升高时发生自旋重取向转变 ,自旋重取向温度Tsr随Er含量的增加而减小 相似文献
3.
CUI Xiao-bing ZHENG Shou-tian SUN Yan-qiong YANG Guo-yu ** . Coordination Hydrothermal Chemistry Group State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou P. R. China . State Key Laboratory of Coordination Chemistry Najing University Nanjing P. R. China 《高等学校化学研究》2004,(1)
IntroductionPolyoxometalatesarewidelystudiedfortheirin terestingapplicationsincatalysis ,electronicconduc tivity ,magnetism ,nonlinearopticsandmedicine[1— 4 ] .Whilethemechanismofthesynthesisofpolyoxometalatesremainselusiveandisoftende scribedasself assembly ,thereseemstobeanincreas inguseofthecombinationofthehydrothermalmethodandthestructure directingtemplate .There searchwiththismethodhasdemonstratedthatanum beroftransitionmetaloxides ,typicallyreducedmolybdenumoxides ,mixedvalancevanadiumo… 相似文献
4.
Q. Gong R. N tzel P.J. van Veldhoven T.J. Eijkemans J.H. Wolter 《Journal of Crystal Growth》2005,280(3-4):413-418
We report on the shape transition from InAs quantum dashes to quantum dots (QDs) on lattice-matched GaInAsP on InP(3 1 1)A substrates. InAs quantum dashes develop during chemical-beam epitaxy of 3.2 monolayers InAs, which transform into round InAs QDs by introducing a growth interruption without arsenic flux after InAs deposition. The shape transition is solely attributed to surface properties, i.e., increase of the surface energy and symmetry under arsenic deficient conditions. The round QD shape is maintained during subsequent GaInAsP overgrowth because the reversed shape transition from dot to dash is kinetically hindered by the decreased ad-atom diffusion under arsenic flux. 相似文献
5.
The Li oxides species formed on Li over-deposited V2O5 thin film surfaces have been studied by using X-ray and UV induced photoelectron spectroscopy (XPS and UPS). The photoelectron spectroscopic data show that the Li over-deposited V2O5 system itself is not stable. Further chemical decomposition reactions are taken place even under UHV conditions and lead to form Li2O and Li2O2 compounds on the surface. The formation of Li2O2 causes to arise an emission line at about 11.3 eV in the valence band spectra. 相似文献
6.
J. Wang J. Kono A. Oiwa H. Munekata C. J. Stanton 《Superlattices and Microstructures》2003,34(3-6):563
We have carried out an ultrafast time-resolved differential reflectivity study of a ferromagnetic semiconductor InGaMnAs and made a systematic comparison with low-temperature grown and high-temperature grown InGaAs reference films. Very short carrier lifetimes (2 ps) were observed in InGaMnAs and the low-temperature grown InGaAs film, but not in the high-temperature grown InGaAs film. We attribute the short lifetimes to carrier trapping by mid-gap states introduced during low-temperature MBE growth. Furthermore, at long times, we observed periodic oscillations in the differential reflectivity signal with period 20 ps, which we interpret as coherent acoustic phonons. 相似文献
7.
Ion synthesis and laser annealing of Cu nanoparticles in Al2O3 总被引:1,自引:0,他引:1
A.L. Stepanov V.N. Popok D.E. Hole I.B. Khaibullin 《Applied Physics A: Materials Science & Processing》2002,74(3):441-446
Al2O3 samples with Cu nanoparticles, synthesised by ion implantation at 40 keV with a dose of 1×1017 ion/cm2 and a current density from 2.5 to 12.5 μA/cm2, were annealed using ten pulses from a KrF excimer laser with a single pulse fluence of 0.3 J/cm2. The copper depth distribution, formation and modification of metal nanoparticles under the ion implantation and laser treatment
were studied by Rutherford backscattering (RBS), energy dispersive X-ray (EDX) analysis, atomic force microscopy (AFM) and
optical spectroscopy. It was found that laser annealing leads to a reduction in the nanoparticle size without diffusion of
metal atoms into the bulk. The change in particle size and the possibility for oxidation of the copper particles are examined
in the framework of Mie theory. Calculations presented show that under excimer laser treatment, Cu nanoparticles are more
likely to be reduced in size than to undergo oxidation.
Received: 19 April 2001 / Accepted: 7 November 2001 / Published online: 23 January 2002 相似文献
8.
陈隆懋 《光谱学与光谱分析》1997,17(4):73-76
本文对国产WLY100型顺序扫描ICP光谱仪在设计中对单色仪,高频发生器,扫描机构,测光系统,短紫外光域的测量,恒温,气流控制与软件编制等方案的选择作了详尽的阐述,稳妥的方案使研制工作顺利进行,保证整机一次成功。 相似文献
9.
Jean Dolbeault Maria J Esteban Michael Loss Luis Vega 《Journal of Functional Analysis》2004,216(1):1-21
We prove some sharp Hardy-type inequalities related to the Dirac operator by elementary, direct methods. Some of these inequalities have been obtained previously using spectral information about the Dirac-Coulomb operator. Our results are stated under optimal conditions on the asymptotics of the potentials near zero and near infinity. 相似文献
10.
Y. Sun G. D. Sanders F. V. Kyrychenko C. J. Stanton G. A. Khodaparast J. Kono Y. H. Matsuda N. Miura H. Munekata 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):374
We present a theoretical and experimental study of electron-active cyclotron resonance in p-doped InMnAs in high magnetic fields. Results are based on an 8-band Pidgeon–Brown model generalized to include finite kz effects and s(p)–d exchange interaction between itinerant carriers and Mn d-electrons. The e-active transitions in the valence band in p-doped samples take place due to the nature of multiple valence bands (heavy and light holes). We have calculated the absorption spectra in high magnetic fields and identified optical transitions which contribute to the cyclotron resonance for both e-active and h-active polarizations. Calculations show agreement with experimental results. 相似文献