材料期刊网

TEXTURE AND MECHANICAL PROPERTIES OF WARM ROLLED Fe_3Al BASED ALLOY

SUN Zuqing , MAO Weimin , CHAI Shuyan , YANG Wangyue , HUANG Yuanding(University of Science and Technology Beijing , Beijing 100081. China)RAABED , KEICHELJ(Institut fur Metallkunde und Metallphysik. RWTH Aachen , Germany)

金属学报(英文版)

The rolling and recrystallization texture of B2 type Fe3Al based alloys were systematially investigated by ODF. The results showed that the rolling texture consisted of a strong β-fibre close to {111} and a {001} <110> texture. In annealing process the rolling texture was strengthened at recovery stage and gradually disappeared during primary recrystallization. A strong shear texture was produced by only 20% Pass reduction, indicating that the Fe3Al is sensitive to shear stress. The corresponding room temperature tensile properties were measured. A correlation between texture mode and room temperature mechanical properties was observed.

关键词: : Fe3Al , null , null , null

Raman Spectroscopic Study of Silicon Nanopowders

S.M.Scholz , J.Dutta and H.Hofmann(Lab. de Technologie des Poudres , Departement de Materiaux , Ecole Polytechnique Federale de Lausanne , 1015 Lausanne , Switzerland)H.Hofmeister (Max-Planck-Institut fur Mikrostrukturphysik , Weinberg 2 , D-06120 Halle , Germany)

材料科学技术（英文）

Vibrational properties of silicon nanopowders are discussed with reference to Raman spectroscopic measurements. The powders were produced in a low pressure rf plasma from the cluster induced agglomeration of positive ions formed during the dissociation of silane. Influence of thermal treatment and the crystallization phenomena of the powder were studied. Raman spectroscopic measurements reveal size quantization effects for the particles as well as the existence of partially ordered regions in the apparently amorphous primary particles. The crystalline and amorphous volume fraction in the material were calculated from the relative spectraI intensities. The results obtained in these experiments are consistent with the observations from recent high resolution transmission electron microscopy studies of these powders

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INTERFACE-RELATED DEFORMATION MECHANISMS AND DISLOCATION MOBILITIES IN TWO-PHASE TITANIUM ALUMINIDE ALLOYS

CHRISTOPH Ulrich , SPARKA Ulf APPEL Fritz , and WAGNER Richard(Institute for Materials Research , GKSS Research Center , Max-Planck-Str. , D-21502 Geesthacht , Germany)

金属学报(英文版)

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Biaxiality Dependence of the Fracture Toughness for Glass in Plane Stress State

Yiwang BAO(China Building Materials Academy , Beijing 100024 , China)R. W Steinbrech (IWE1 , Juelich Research Center , Germany)

材料科学技术（英文）

The fracture behaviour of glass in biaxial stress state has been investigated. Fracture toughness of disk specimen with a straight-through crack was measured under biaxial tension and uniaxial tension loads respectively. The difference between them and the reasons for the difference are discussed. The influence of the stress parallel to crack on fracture of brittle material was demonstrated in theory and experiments. The results show that plane stress fracture toughness of glass is not a material constant. and that the fracture toughness measured in biaxial tension state is higher than that measured under uniaxial tension. The conventional fracture criterion upon the stress intensity factor is questioned in the case of biaxial stress problem, and the strain dependence of crack growth is discussed.

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Magnetothermal Analysis of Nanocrystallization of Amorphous and Relaxations of Nanocrystalline Materials

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

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Nobel Prize for Our Advisor, Gerhard Ertl, Germany

催化学报

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OXIDE METALLURGY-ITS PURPOSES AND PRACTICAL APPROACHES

Z. T. Ma and D. Janke(Institute of Iron and Steel Technology , Freiberg University of Mining and Technology , Germany)

金属学报(英文版)

Useder certain conditions, nonmctallic inclusions such as oxides, sulfides, nitrides and carbides are no longer harmful to sted service properties. With the new concept of oxide metallurgy, these properties can be improved by generating fine oxide inclusions which serve as heterogeneous nuclei for sulfide and fine ferrite[1-4]. A novel continuous casting (CC) process is expected to be created with the utilization of oxide metallurgy. This is also useful for the forthcoming technologies of direct rolling and near-net-shape casting. The main idea of oxide metallurgy consists of an alternative oxidation technology. It is based on steels treated by complex metals such as Ti, Zr, Ti-Zr alloys and rare earth metals. The selected deoxidants should follow the required conditions which are concluded in this paper.

关键词: oxide , null , null , null

AN ASSESSMENT OF INTERACTION PARAMETERS IN BINARY　METALLIC SYSTEMS

Z. T. Ma and D. Janke(Institute of Iron and Steel Technology , Freiberg University of Mining and Technology , Germany)

金属学报(英文版)

An approach of describing the thermodynamics of binary alloys is developed which is based on an exact expression of infinite MacLaurin series of molar excess Gibbs free energy. This new approach is successfully used to represent the thermodynamics of binary alloys at higher concentrations. The present results reveal that it is an improper way to evaluate first and second-order interaction parameters simultaneously from the experimental data in the range of higher concentrations due to an inadequate accuracy Of high temperature experiments.

关键词: thermodynamics , null , null , null

THERMODYNAMIC PROPERTIES OF NITROGEN IN Fe-Cr-Ni ALLOYS AT 1873K

Z.T.Ma and D. Janke (Institute of Iron and Steel Technology , Freiberg University of Mining and Technology , Germany)

金属学报(英文版)

Thermodynamic behavior of nitropen in Fe-Cr-Ni alloys at 1873K is discussed in the present study. The dependence of upon the content of Cr in Fe-Cr-Ni-N melt is expressed. The present authors' formalism[17] developed for describing thermodynamics of metallic multicomponent systems is successfully applied to the Fe-Cr-Ni-N quaternary system.

关键词: Fe-Cr-Ni alloy , null , null

Controlled synthesis of cobalt flowerlike architectures by a facile hydrothermal route

European Journal of Inorganic Chemistry

Cobalt flowerlike architectures composed of hexagonal nano-platelets have been synthesized by a simple hydrothermal. reduction method. The architectures are fabricated by the reaction Of COCl2 with NaOH at 140-180 degrees C in the presence of sodium dodecyl benzenesulfonate (SDBS), with NaH2PO2 center dot H2O as reducing agent. The diameters of the flowers range from 8 to 10 mu m, and the average thickness of the hexagonal sheets is about 100 nm. Higher reaction temperatures and the proper concentration of sodium hydroxide (NaOH) are key requirements for the fabrication of the flowerlike architectures. A growth mechanism for these architectures is proposed on the basis of the characterization by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The magnetic hysteresis loops at 5 K and 295 K of the cobalt flowerlike architectures show ferromagnetic characteristics with coercivities of 371 Oe and 197 Oe, respectively. Our work may shed light on the designed fabrication of complex 3D architectures of other materials. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008.

关键词: hydrothermal synthesis;cobalt;nanostructures;magnetic properties;gold nanoparticle arrays;anisotropic growth;self-organization;nanoplatelets;superlattices;nanocrystallites;superstructures;nanostructures;construction;aggregation