YANG Jilian ZHANG Baisheng JIN Lan DING Yongfan YE Chuntang Institute of Atomic Energy
,
Beijing
,
ChinaYANG Yingchang SUN Hong KONG Linshu Peking University
,
Beijing
,
China YANG Jilian
,
Associate Professor
,
P.O.Box 275
,
Sub 80
,
Beijing 102413
,
China
金属学报(英文版)
The site occupancies in permanent magnetic alloy Y_2(Fe_(0.95)Al_(0.05))_(14)B has been studied by means of neutron diffraction.The results from profile refinement show that Al enters the tetragonal structure of Nd_2Fe_(14)B and occupies the 4c and 8j_2 sites of the space group P4_2/mnm preferably.The relation between the site occupancies and the magnetic proper- ties is discussed preliminarily.
关键词:
Y_2(Fe_(0.95)Al_(0.05))_(14)B
,
null
,
null
,
null
Riguarng JIN and Hangquan LI(Bejing Institute of Chemical Technology
,
Beijing
,
100029
,
China)
材料科学技术（英文）
Series of PVC/ABS and PVC/SBS blends of composition 20/ 80. 40/ 60, 60 / 40 and 80 / 20were prepared in a screw extruder. The phase morphology, miscibility and rheological behaviour of two systems were investigated. The viscosity-composition plots were represented by sub-cluster equation, the various differences between two systems are interpreted with the equation parameters
关键词:
S.Z.Dong
,
J.B.Li
,
X.H.Zhang and J.Zhang Shenyang University
,
Shenyang 110044
,
China
金属学报(英文版)
With TEM( Transmission Electron Microscope) ,ithasobserved and analyzedthatforming processof Sub grainsand position offormingfatigue microcracksarein Welded metalsofthe16 Mnsteelundertensile tensilestress. Theresultsindicatedthattheforming processof Sub grainsfrom dislocationtanglecellstotheSub grains. Thepositionofformingfatigue micro crackisattheoxidativeinterfaceand granular noncrgstallines and Sub boundaries. Thece mentiteineutectoidsafterfracture may beproduced microcracks.
关键词:
fatigueload
,
null
,
null
,
null
H.J.FAN
,
M.Zacharias
材料科学技术（英文）
Vapor-phase growth of ZnO nanowires based on gold catalyst is usually accompanied with lateral crawling growth on the substrate surface. We present results from our systematic experiments where the growth temperature and catalyst size are controlled. The data corroborate that it is possible to obtain clean vertical nanowire arrays while avoiding the crawling growth. On the other hand, crawling growth can be manipulated to obtain root-interconnected nanowire arrays, which could be useful for certain applications. Our results also imply that the previously suggested growth mechanism for the wire-on-wall hybridstructure might be incorrect. Finally, we show the formation of sub-millimeter long, straight ZnO nanowalls by combining a gold-catalyzed epitaxial growth of vertical nanowires and their mergence due to a confined crawling growth. These unconventional nanostructures might have unique electric or optical transport properties.
关键词:
Nanowire
,
nanowall
,
ZnO
,
crawling
,
growth
HOU Yan-qing
,
XIE Gang
,
TAO Dong-ping
,
LI Rong-xing
,
YU Xiao-hua
钢铁研究学报(英文版)
To confirm sub-regular solution model valid for predicting the activity of component in binary oxide systems, seven systems in the whole concentration and twelve systems presenting saturation concentration have been studied. The total average relative errors of component 1 and 2 are 3.2% and 4.1% respectively by application of the sub-regular solution model into the systems within the whole concentration. However, the total average relative errors are 16% and 1088% in the systems presenting saturation concentration. The results show that sub-regular solution model is not good for predicting the systems presenting saturation concentration, especially for the systems containing acidic or neutral oxide. The reason may be that the influence of the two types of oxide on the configuration is greater in binary oxide systems. These oxides can be present in the form of complex anion partly, Si-O, Al-O, Ti-O and so on, for example (SiO4)4-. That is contrary to sub-regular solution model which is supposed that the oxide systems consist of cation and O2-. But compared with regular solution model and quasi-regular solution model, sub-regular solution model is closer to the characteristics of actual solution and the calculated results are superior.
关键词:
sub-regular solution model
,
binary oxide system
,
activity
Physica Status Solidi a-Applications and Materials Science
Based on the thermal evaporation of silicon monoxide at high temperature, an improved method has been developed for large-scale synthesis of ultralong amorphous silica sub-micron wires using polished p-Si wafers as substrates. The synthesis was done with and without thermite. The morphology and structure of the silica wires was investigated through field-emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and X-ray diffractometer. Almost uniform sub-micron wires with average diameters of 300 nm and length up to hundreds of micrometers were obtained in presence of thermite while sub-micron wires with many curved segments were obtained in absence of the thermite. Both forms of silica wires emitted blue lights at 478 nm (similar to 2.6 eV) under excitation at 351 nm (similar to 3.5 eV), while intense anti-Stokes blue emissions at 464 nm(similar to 2.7 eV) were observed under the 694 nm(similar to 1.8 eV) excitation due to the upconversion effect. This effect is associated with defect centers arising from high oxygen deficiency. The emissions from oxygen deficiency centers might be caused by multistep energy transfer from nonbridging oxygen hole centers to oxygen deficiency centers. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
关键词:
nanowires;photoluminescence;silica;thermal evaporation;upconversion;transfer up-conversion;photoluminescence properties;nanowire growth;deposition;mechanism;pressure;dioxide;centers;lasers
Chinese Physics Letters
Al(85)Ni(5)Y(8)Co(2) and Al(85)Ni(5)Y(6)Co(2)Fe(2) metallic glasses are fabricated by melt spinning. A kink or a small exothermic peak is observed for both the samples isothermally annealed at sub-glass transition temperatures. Temperature modulated differential scanning calorimetry (TMDSC) data disapprove amorphous phase separation. The activation energies derived from Kissinger plots of the exothermic process on DSC curve around glass transition temperature are consistent with those of beta-relaxation of metallic glasses.
关键词:
phase-separation;nanocrystalline alloys;crystallization;transition;behavior
Optics Express
We measure second-harmonic generation from arrays of sub-wavelength apertures in transmission using fundamental input at 800 nm. Lattice arrangements include disordered, Penrose (quasi-periodic or aperiodic), and square (periodic). Strong angular dependence of SHG is observed, with maxima located at angular positions that roughly correspond to incidence angles of extraordinary optical transmission (EOT) for the fundamental. In addition, even at incidence normal to the sample, strong secondary maxima are observed at off-normal scattering angles for the arrangements with higher degree of order. Breaking the inversion symmetry of the aperture allows second harmonic peaks at normal incidence and detection. These measurements help to resolve the role that symmetry plays in second-harmonic generation from arrays of apertures. (c) 2007 Optical Society of America.
关键词:
metal-film;optical-transmission;hole arrays;generation;enhancement
Transactions of Nonferrous Metals Society of China
The WC-10%Co particulate reinforced Cu matrix composite material with a WC-Co : Cu mass ratio of 20 : 80 was successfully fabricated by selective laser sintering(SLS) process. The following optimal processing parameters were used: laser power of 700 W, scan speed of 0.06 m/s, scan line spacing of 0.15 mm, and powder layer thickness of 0.3 mm. The microstructure, composition, and phase of the laser processed material were investigated by scanning electron microscopy(SEM), X-ray diffraction(XRD), and energy dispersive X-ray(EDX) spectroscopy. The results show that the bonding mechanism of this process is liquid phase sintering. The Cu and Co act as the binder phase, while the WC acts as the reinforcing phase. The non-equilibrium effects induced by laser melting, such as high degrees of undercooling and high solidification rate, result in the formation of a metastable phase CoC0.25. The WC reinforcing particulates typically have three kinds of morphology. They are agglomerated and undissolved, incompletely separated and partially dissolved, separated and dissolved, which indicates that particle rearrangement acts as the dominant sintering mechanism for the larger WC, while dissolution-precipitation prevails for the smaller WC particles. Microhardness tester was used to determine the Vickers hardness across the cross-section of the laser sintered sample, with the average value being HV(0.1)268.5. However, the hardness varied considerably, which might be attributed to the WC segregation and the high solidification rate experienced by the molten pool.
关键词:
selective laser sintering;metal matrix composites;Cu matrix composite;WC-Co;Cu;microstructure;microhardness;wc-co;metal powders;densification;alloy;parts
