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1IntroductionRaredispersiveelementsGa,InandTlformthecomplexesofdiferentcoordinatenumber(CN)orcoordinatestructure(CS)withamin... 相似文献
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Mechanical properties and creep resistance of Mg-Li composites reinforced by MgO/Mg_2Si particles 总被引:2,自引:0,他引:2
1 INTRODUCTIONMg Lialloyisanewandsuper lightstructuralma terial.Itiswidelyusedinspaceandweaponindustrybecauseofhigherspecificstrengthandrigidity .Someresearch[1~8] indicatedthat:1 )thestrengthofbinaryalloyislowerandthecreepresistanceisverypoor;2 )thestrengthca… 相似文献
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1 INTRODUCTIONAluminummatrixcompositereinforcedwithsili concarbidewhisker (SiCw/Al)asanewtypeofstructuralmaterialnotonlyhascertainadvantagessuchashighspecificstrength ,highspecificmodulus ,lowcoefficientofthermalexpansion (CTE)andsoon ,butalsocanbesecondari… 相似文献
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1 INTRODUCTIONBecauseofthespecialatomoccupationincrys tallinelattice,thedislocationstructureofinter metallicsisrelatedtotheformationofanti phasedo mainboundary ,forwhichthecrystallographicbehav iorsoftheplasticdeformationisdifferentfromthatoftheconventio… 相似文献
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Elastic modulus of SiC_w/6061Al alloy composites as-squeeze-cast 总被引:1,自引:1,他引:0
1 INTRODUCTIONCompositeofsiliconcarbidewhiskerreinforcedaluminum (SiCw/Al)asanewtypeofstructuralma terialnotonlyhassomeadvantagessuchashighspe cificstrength ,highspecificmodulus ,lowthermalco efficientofexpansionandsoon[1,2 ] ,butalsocanbesecondarilyshapedbyth… 相似文献
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1 INTRODUCTION1.1 ThixoformingIntheearly 1970s ,aspecialthixotropicmi crostructureinsemisolidstatewasdiscoveredwhenFlemingsandhisco workersstudiedthe“hottears”ofthecastingalloys[1] .Theapparentviscosityofthesemisolidmaterialsdeclinessharplywiththeincreaseofth… 相似文献
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BIAN Zhan 《中国有色金属学会会刊》2000,10(3)
1 INTRODUCTIONThecrystallizationbehaviorinmulticomponentamorphousalloysiscomplicated,dependinggreatlyonalloycompositionandmicrostructure,heatingprocessandascastamorphousstate,andsoon.Sometimesmetastablephasesappearbeforethermallystableequilibriumphase.T… 相似文献
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1 INTRODUCTIONThesolidificationprocessofbinaryAl Fealloyundercentrifugalcastingiscontrolledbythemass,momentum ,heatandchemicalspeciestransporta tion .Therefore,itisanimportantmeanstoknowthemicrostructureandthesegregationofbinaryAl Fealloyundercentrifugalc… 相似文献
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1 INTRODUCTIONThestudyofmoltenstructureofCaO SiO2 ,whichactasthebasicfactorinfluencingthephysicalandchemicalpropertiesofthesilicat 相似文献
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MicrostructureandTransformationonPlatinum(111)FacetsWangLianshanHongHanlie(汪连山)(洪汉烈)(WuhanUniversityofTechnology,Wuhan430070,... 相似文献
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CAO Mingzhou XIE Yingxiu XU ZengjiInstitute of Metal Research Chinese Academy of Sciences Shenyang. China 《金属学报(英文版)》1994,7(1):12-18
The microstructure and compressive properties of Ti_(500Al_(48)Mn_2and Ti_(50)Al_(48)Cr_2 alloys are studied in this paper Existence of αx y transforntation in TiAl alloys is confirnted by metallographic examincttion,the transformation temperatuses of Ti_(50)Al_(48)Mn_2 and Ti_(500Al_(48)Cr_2,are 1375and 1373C respeclively,After treating withic x y phase field,themicrostructure of alloys consists of lamellar zones(L)and bulk y_p.,The vohme ratio of L/y_p inctrases with increasing solution treatnient temperature.The third alloying ele-ments of Mn and Cr distribute perfentially over αphase at solution treatment tempera-tures and result in that α_2 and γ lamellae become thicker.The yield strength of Ti_(50)Al_(48)Mn_2 and Ti_(500Al_(48)Cr_2 alloys decreases and the compressibllity increases with in-creasing γ_p volume fraction. 相似文献
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研究了用部分Ca取代LPC(LPC为无钕镧镨铈混合稀土金属),同时用部分Ni取代Mg的(LPCCa)2(MgNi)17合金的吸放氢性能。比较了不同温度下,不同成分配比对合金贮氢性能的影响。其中,(LPC)1.9Ca0.1Mg15Ni2合金具有相对较低的放氢温度和较大的放氢节,住275℃的放氢量达3.43%(质量分数)。分析了(LPC)1.9Ca0.1Mg15Ni2的微观结构,同时对合金放氢温度降低的原冈进行了讨论。 相似文献
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The thermal decomposition of Tb2(O-MBA)6(PHEN)2 (O-MBA: o-methylbenzoate; PHEN: 1,10-phenanthroline)and its kinetics were studied under the non-isothermal condition by thermogravimetry-derivafive thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtained from analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as dα/dt = Aexp(-E/RT) @ 3(1 - α)2/3. The lifetime equation at mass loss of 10% was deduced as lnτ= -28.7429 + 19797.795/T by isothermal thermogravimetric analysis. 相似文献
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R. F. Brebrick 《Journal of Phase Equilibria》2000,21(3):235-240
The optical density of the vapor generated by SeO2 (s) between about 416 and 505 K has been measured between 400 and 200 nm for optical path lengths of 10.14 and 10.15 cm and temperatures of 533, 733, 1133, and 1420 K. A pressure of oxygen of about 0.7 to 0.9 atm was present in the cells and that of Se2 was below the minimum detectable of about 0.001 atm. For one cell, complete vaporization occurred at 481.5 K and a vapor pressure of 5.02 × 10−3 atm was calculated from the weight of SeO2 (s), the volume profile of the optical cell, and the temperature distribution along the cell. Assuming Beer’s law is obeyed for a number of vibronic peaks, the vapor pressure is obtained as log10 P (atm)=−5705/T+9.5443 in close agreement with two studies with fused silica Bourdon gauges. Beer’s law constants relating the pressure to the optical density at various wavelengths are obtained for the optical path temperatures listed above. Thermodynamic data previously published for solid and liquid SeO2 need be changed only slightly to be consistent with the present vapor pressure. We obtain a standard enthalpy of sublimation at 298 K of 112.70 kJ/mol and standard entropies at 298 K of 258.72 and 66.693 J · mol−1 · K−1 for, respectively, gaseous and solid SeO2. 相似文献
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ZHANG Jianjun BAIJihai WANG Ruifen WANG Shuping and LI Jibiao) Experimental Center Hebei Normal University Shijiazhuang China) Department of Computer Hebei Normal College of Science Technology Changli China) Department of Chemistry Hebei Normal University Shijiazhuang China 《稀有金属(英文版)》2003,(3)
The thermal decomposition of Tb2(O-MBA)6(PHEN)2 (O-MBA: o-methylbenzoate; PHEN: 1,10-phenanthroline) and its kinetics were studied under the non-isothermal condition by thermogravimetry-derivative thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtained from analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as dcddt = Aexp(-E/RT) 3(1 - α)2/3 The lifetime equation at mass loss of 10% was deduced as lnr= -28.7429 + 19797.795/Tby isothermal thermogravimetric analysis. 相似文献
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《Synthetic Metals》2002,130(2):129-134
The (D1)2Cu2Br4,2CH2Cl2 (1) and (D1)2Cu2Br6 (2) radical cation salts, where D1 is the outer S-position isomer of ethylenedithiodimethylthiotetrathiafulvalene (EDT-DMT-TTF), have been synthesized and their X-ray crystal structures have been solved. The molecular structure of 1 is built up from (D1–Cu2Br4–D1) metal complexes. Each copper(I) atom is coordinated to a sulfur atom of the D1 disulfide bridge through a σ-type dative bond. Consequently, Cu2Br4 part is located between two organic molecules which are approximately plane and parallel to each other. In compound 2, (Cu2Br6)2− anions, in which copper atoms are at the +2 oxidation state, also lie between two oxidized donors. In both resulting structures, the D1–Cu2Brx–D1 parts (x=4 for 1, x=6 for 2) are stacking in order to form columns containing dimerized (D1+)2 units. 相似文献
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《Synthetic Metals》2001,123(1):129-133
We report on spectroscopic studies of the charge transfer salt formed by the organic donor bis(ethelenedithio)tetrathiafulvalene (BEDT-TTF) and [Pt(NO2)4]2− anions. In this salt BEDT-TTF molecules are arranged in well-isolated (BEDT-TTF+)2 dimers. Polarized reflectance spectra of single crystals were measured in the IR region (650–6500 cm−1). Moreover, absorption spectra (400–15,000 cm−1) and FT-NIR Raman spectra of powdered crystals dispersed in KBr pellets were recorded. Vibrational and electronic features are discussed. We suggest that the frequency of the CC stretching ν3(ag) mode depends non-linearly on the degree of ionization of BEDT-TTF. 相似文献
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《Synthetic Metals》1995,73(3):227-237
Protonated (I) and deuterated (II) crystals of (ET)2[Hg(SCN)2Br] (ET = bis(ethylenedithio)tetrathiafulvalene) are isostructural with B2/b space group and Z = 4. Crystal structure consists of (ET)2+ dimers forming a κ-type motif and arranged in layers parallel to the bc-plane which are separated by anionic sheets of polymeric anions. A two-positional disorder exists in ethylene groups of deuterated ET molecules, while such disorder appears only in one of the ethylene groups in the hydrogenated salt. The crystals exhibit semimetallic behaviour at high temperatures with a transition to non-metallic state at 100 K for salt I and 60 K for salt II as is shown from d.c. conductivity measurements. Electron spin resonance (ESR) g factor and linewidth and their temperature behaviour are extensively discussed on the basis of existing theories and experimental data for low-dimensional organic conductors. The linewidth is determined by spin-phonon scattering driven relaxation processes which are mediated by Peierls fluctuations in the conducting phase and by spin-lattice relaxation processes below the critical temperature. The first-order phase transition in hydrogenated salt at 100 K is associated with a localization of electrons on ET dimers, whereas the transition of semiconductor-semiconductor type with possible magnetic ordering is suggested for deuterated salt. A considerable isotope effect in (ET)2[Hg(SCN)2Br] is considered to be related to a weak hydrogen bond between the terminal ethylene group of ETdot;+ and the bromine atom of the anion in hydrogenated salt. A discussion of the nature of the phase transitions is given. 相似文献