Reinhard L■ck(Max-Planck-Institut fur Metallforschung
,
Institut fur Werkstoffwissechaft
,
Seestraβe 75
,
D-70174 Stuttgart
,
Germany)
材料科学技术（英文）
For a few years it has been realized that nanocrystalline phases can be formed during crystallization of amorphous alloys annealed isothermally below the crystallization temperature of usual heating experiments. Data of this transformation monitored by the measurement of magnetic susceptibility are presented. A method using a magnetic balance with electronic stabilisation and combined computer facilities is applied. Constant heating and cooling rates as well as isothermal heat treatments are used. Magnetic measurements are able to detect the onset of the transformation of amorphous Ni-P alloys much earlier than was possible with differential scanning calorimetry. The transformation kinetics can be analyzed by means of the Avrami plot based on the Johnson-Mehl-Avrami equation.The kinetics of solid state reactions in the nanostructured material can be investigated similarly. Formation of a Ni-phase in a nanostructured Hf-Ni alloy could be detected in a very early stage, where calorimetric methods are not sensitive. Segregation phenomena could be detected from the experiments even after long time. The sensitivity of the applied method is not dependent on the heating rate as the sensitivity of scanning calorimetry is
关键词:
European Physical Journal B
Moving nonlinear localized vibrational modes (i.e. discrete breathers) fur the one-dimensional homogenous lattice with quartic anharmonicity are obtained analytically by means of a semidiscrete approximation plus an integration. In addition to the pulse-envelope type of moving modes which have been found previously both analytically and numerically, we find that a kink-envelope type of moving mode which has not been reported before can also exist for such a lattice system. The two types of modes in both right- and left-moving form can occur with different carrier wavevectors asd frequencies in separate parts of the omega(q) plane. Numerical simulations are performed and their results are in good agreement with the analytical predictions.
关键词:
diatomic chains;stability;solitons;equation
杨成雄
,
王士伟
,
严秀平
应用化学
doi:10.11944/j.issn.1000-0518.2016.09.160211
以吸附等温线、动力学和热力学等方法研究了金属-有机骨架对苯二甲酸酯-铝[MIL-53(Al),MIL:Materials of Institut Lavoisier]对水中邻硝基苯酚、苯酚和邻苯二酚的吸附行为.MIL-53 (Al)对上述酚类化合物的吸附符合准二级吸附动力学模型,且包含表面吸附和孔内扩散两个过程.吸附热力学结果表明,MIL-53(Al)对酚类化合物的吸附是自发的,且为吸热和熵增加过程.在40℃条件下,MIL-53 (Al)对邻硝基苯酚、苯酚和邻苯二酚的吸附量分别为78.6、30.5和16.5 mg/g.
关键词:
金属-有机骨架
,
吸附
,
酚类化合物
,
对苯二甲酸酯-铝
W. L. Zhou
,
J. T. Guo
,
R.S. Chen and J. Y Zhou(Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)(Department of Materials Engineering
,
Dalian University of Technology
,
Dalian 116024
,
China)
金属学报(英文版)
Our previous investigation examines the soperplastic behavior of an extruded Ni-28.5Al-20.IFe alloy. Its tensile properties were determined at temperature from 1123Kto 1323K and initial strain rates from 1.0{x 10-2s-1 to 1.04x 10-4s-1. A maximumelongation of 233K was obtained at 1123K and a strain rate Oj 5.2x 10-4s-1. Fur-thermore, microstructural features, such a8 decrease in the avempe gmin Bize afier de-formation at 85dC and 98dC the presence oj many dislocationthee gmins adjacentto grains with a high dislocation density, indicate that dynamic recrystallization hasoccuwed as an decient accotnmodation mechanism. SEM examination Of the fracturesample afier saperplastic defOrmation revealS many voids on the hecture sudece. Bycoerelating with the results Oj TEM observation, it is sopested that the soperplasticdejormation in this alloy should be controlled by a gmin boundarp sliding-based mech-anism accommodated by the movement oj dislocation and dynamic recrpstallization.
关键词:
Ni-Al-Fe intermetallics
,
null
Acta Materialia
The effect of alloying elements Cr and Mn on the cohesion of the gamma -iron Sigma 11[1(1) over bar 1]/(11(3) over bar) grain boundary (GB) is investigated based on the thermodynamic model of Rice-Wang by using the first-principles density functional theory. The electronic properties are studied fur Cr/Fe and Mn/Fe systems. In these systems, the chemical effect of Cr and Mn is in favor of enhancing the cohesion of the grain boundary due to the anisotropic bonding which weakens the bonds in the grain boundary plane, but strengthens those in planes perpendicular to the grain boundary. However, the structural relaxation effect is detrimental to the cohesion of the grain boundary. After synthesizing these two effects, Cr can act as a cohesion enhancer and Mn is an embrittler. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.
关键词:
computer simulation;gamma-iron;grain boundaries;segregation;electronic-structure;phosphorus segregation;stainless-steel;embrittlement;austenite;boron;manganese;sulfur;carbon;ni3al
Physica Status Solidi B-Basic Research
The influences of the squeezing-antisqueezing effect arising from variations of the electron density and motion of polarons and nonadiabatic phonon fluctuations on the properties of the ground state and the binding energy of the polaron in the Holstein model of coupled one-dimensional electron-phonon systems with spin 1/2 in the cases of high and low electron densities have been studied by using the Bogolyubov transformation and a new ansatz fur states that includes correlation effects among the one-phonon coherent and two-phonon squeezed and polaronic states. The results obtained show that the squeezing-antisqueezing (correlation) effect results in that the ground state energy of the systems is significantly lowered, and the binding energy of the polaron is considerably increased. Thus, the stability of the systems and of the polaron are obviously enhanced in such a case when compared with the uncorrelated case. This shows that the ground state determined by the new state ansatz is most stable, and the new ansatz introduced here is very relevant for the coupled electron-phonon systems, especially in strongly coupled and largely squeezed cases.
关键词:
molecular-crystal model;bipolaronic superconductivity;quantum;fluctuations;phase-diagram
Physica Status Solidi a-Applied Research
Photoluminescence and Raman scattering spectra were used to study three types of free-standing porous Si: as-grown samples with various porosities referred to as APS samples, these samples oxidized in air at 200 degreesC fur 200 h as OPS samples, and these samples aged further in air at room temperature for 20 months as AOPS samples. The PL peak energies of OPS and AOPS samples have shifted in small energy ranges centered at about 1.61 and 1.59 eV, respectively. Each Raman spectrum was fitted with an amorphous and a crystalline component. The crystalline component was used to determine the sizes of nanometer Si particles (NSPs), which were in ranges of 2.5-2.2 and 3.3-2.3 nm in OPS and AOPS samples, respectively. The reason why OPS or AOPS samples with different NSP sizes have almost the same FL peak wavelength is discussed with a novel multiple mechanism model.
关键词:
optical-properties;silicon films;luminescence;spectra;semiconductors;mechanism
李翠侠
,
刘绍璞
,
刘忠芳
,
胡小莉
应用化学
doi:10.3724/SP.J.1095.2010.90831
在pH为5.0～7.6的Britton-Robinson(BR)缓冲溶液中,呋塞米(FUR)与Pd(Ⅱ)形成摩尔比1∶ 1的配合物,进一步与乙基紫(EV)、结晶紫(CV)、甲基紫(MV)、亮绿(BG)、甲基绿(MeG)等碱性三苯甲烷染料(BTPMD)作用形成1∶ 1的离子缔合物时,染料发生褪色反应,褪色波长分别位于595 nm(EV、CV体系)、580 nm(MV体系)、615 nm(BG体系)和630 nm(MeG体系),FUR浓度在2.0×10-7～4.0×10-6 g/mL(EV体系)、3.0×10-7～8.0×10-6 g/mL(CV体系)、4.0×10-7～4.0×10-6 g/mL(MV体系)、4.0×10-7～7.0×10-6 g/mL(BG体系)、1.2×10-6～8.0×10-6 g/mL(MeG体系)范围内与褪色波长处的吸光度变化值呈良好的线性关系,摩尔吸光系数(ε)根据染料的不同在0.57×104～3.40×104 L/(mol·cm)之间,灵敏度最高的EV体系的检出限(3σ)为6.0×10-8 g/mL,据此建立一种测定呋塞米的新分光光度法. 研究了适宜的反应条件、分析化学性质和共存物质的影响,用于尿样中呋塞米的含量测定,回收率在96.0%～106.8%之间.
关键词:
Pd(Ⅱ)
,
呋塞米
,
三苯甲烷染料
,
分光光度法
