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Microstructural Evolution during Forming of Metals

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Journal of mat.rials Science & Technology 2001年第4期17卷 409-412页

作者： N.Hansen mat.rials res.arch Department, Risφ National Laboratory,DK-4000 Roskilde, Denmark mat. res. dept. Ris. Natl. Lab. DK-4000 Roskilde Denmark

The microstructural evolution during plastic deformat.on is described as grain subdivision on a finer and finer scale with increasing strain. Key structural features.are dislocation boundaries and high angle boundaries. These boundaries have characteristic parameters which are used in a comparison of deformat.on microstructures.produced under different conditions.

关键词： Microstructural Evolution during Forming of Metals ECAE

Relations between Quenching Rate and Electrochemical Characteristics of Mm (NiCoMnA1) 5Bx (x=0～0.2) Electrode Alloys

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Journal of Rare Earths 2004年第Z1期22卷 235-241页

作者： Zhang Yanghuan dept. of Functional mat. res. Central Iron and Steel Res. Inst. Beijing 100081 China Sch. of mat. Inner Mongolia Univ. of Sci. Baotou 014010 China

Low-Co AB5-type Mm(NiCoMnAl)5Bx(x=0, 0.1, 0.2) electrode alloys were prepared by casting and rapid quenching. The effects of the rapid quenching on the lattice constants, microstructures.and electrochemical characteristics of the alloys were investigated in detail. The obtained res.lts show that the rapid quenching made lattice constants and cell volume increased. In a range of the quenching rate, rapid quenching can increase the discharge capacities of the alloys. However, the discharge capacity of the as-quenched alloy is lower than that of the as-cast alloy when quenching rate is more than a critical value. The cycle lives of the alloys increase monotonously with the increase of the quenching rate.

关键词： AB5-type electrode alloy Electrochemical characteristics Low-Co Microstructure Rapid quenching

PLASMA MODEL-ONE MODEL OF ELECTROMAGNETIC res.ONSE OF mat.ER

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 501-505页

作者： H. Du, J. Gong, C. Sun, A.L. Ji, R.F. Huang and L.S. Wen (The Department of Surface Engineering of mat.rials, Institute of Metal res.arch, The Chinese Academy of Sciences, Shenyang 110016, China) dept. of Surface Eng. of mat. Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

The prerequisite and mode of electromagnetic res.onse of nano metal/dielectric films to electromagnetic wave field were suggested. With the carrier density and the reflectance, transmittance of the film, the plasma frequency and the dependence of absorptance on the frequency of electromagnetic wave field were calculated res.ectively. The calculated res.lts accorded with the experimental ones, which proved the plasma res.nance is one mode of electromagnetic res.onse.

关键词： Aluminum Dielectric films Electromagnetic wave absorption Nanostructured mat.rials

Microstructures.and Creep Behavior of a Directionally Solidified NiAl-Fe(Nb) Multiphase Intermetallic Alloy

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Journal of mat.rials Science & Technology 2003年第1期19卷 59-62页

作者： Yihui QI, Jianting GUO and Chuanyong GUIDepartment of Superalloys, Institute of Metal res.arch, Chinese Academy of Sciences, Shenyang 110016, China dept. of Superalloys Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China dept. of mat. Eng. Liaoning Inst. of Technol. Jinzhou 121001 China

The microstructure and creep behavior of a DS NiAI-Fe(Nb) multiphase intermetallic alloy have been investigated. This alloyexhibits dendritic structure, in which dendritic arm is β-(Ni,Fe)(Fe,Al) phase surrounded by interdendritic region of γ'/γ *** res.lts of the creep test indicated that all of the creep curves have similar characteristic, which is a short primary creepstage and a dominant steady state creep stage, and the creep strain ranges from 18% to 52%. The apparent stres. exponentand the apparent activation energy were analyzed and discussed. The mechanism of the creep deformat.on was also analyzedby the observation of TEM.

关键词： NiAl Multiphase intermetallic alloy Microstructure Creep

In-situ Composite Based on Poly (ethylene terephthalate),Polyamide and Polyethylene with Microfibres.Formed through Extrusion and Hot Stretching

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Journal of mat.rials Science & Technology 2002年第5期18卷 419-422页

作者： ZhongmingLI MingboYANG RuiHUANG AiLU JianminFENG Lab. of Polymer mat. Dept. of Polymer Mat. Sci. and Eng. Sichuan Univ. Chengdu 610065 China

In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter. The extrudate was drawn at a drawing ratio of 3.1, and then quickly cooled in cold water. The specimens were obtained by injection molding at processing temperatures.less than 190℃, far below the melting temperature of PET (265℃) and PA (230℃), which can maintain the solid state of PET and PA microfiber phase in the composites. Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0~20 wt pct PET or PA), and especially, PET and PA were almost deformed into fibers at the concentration of 15 wt pct. Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test res.lts. The most noticeable improvement of the tensile properties occurred at 15 wt pct of PET in PET/PE system, corres.onding to the highest microfiber content, where the tensile strength reached 32.5 MPa, whereas only 19.5 MPa for the pure PE.

关键词： In-situ composite. Polyethylene. Polyamide Polyterephthalate

AMORPHIZATION IN Nb-M (M=Fe, Co, Ni) BINARY METAL SYSTEMS INDUCED BY ION BEAM ASSISTED DEPOSITION (IBAD)

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Acta Metallurgica Sinica(English Letters) 2002年第2期15卷 160-166页

作者： F.Pan, F. Zeng and B. Zhao Laboratory of Advanced mat.rials, Department of mat.rials and Engineering, Tsinghua University, Beijing 100084, China Lab. of Adv. mat. Dept. of Mat. and Eng. Tsinghua Univ. Beijing 100084 China

Ion beam assisted deposition technique (IBAD) was utilized to systemat.cally study amorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe, Co or Ni). The glass forming range termed as Nb fraction of Nb-Fe system was about 34at.% to 56at.%, that of Nb-Co system was about 32at.% to 72at.% and that of Nb-Ni about 20at. % to 80at. %. Similar percolation patterns were found in amorphous alloy films. The fractal dimensions of the percolation patterns approach to 2, which indicates 2-D layer growth for amorphous phases. It is regarded that the assisted Ar+ ion beam during the deposition process plays important role for the 2-D layer growth. Some metastable crystalline phases were obtained in these three systems by IBAD, e.g., bcc supersaturated solid solutions in Nb-Fe and Nb-Co systems, fcc and hcp phases in Nb-Co and Nb-Ni systems. The format.on and competing between the amorphous and the metastable crystalline phases were determined by both the phases' thermodynamic states in binary metal systems and kinetics during IBAD process.

关键词： amorphization ion beam assisted deposition glass forming range metastable phase

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Atomic phase diagram

Progres. in Natural Science:mat.rials International 2004年第2期14卷 17-22页

作者： LI Shichun*(mat.rials Department, University of Petroleum, Dongying 257061, China) mat. dept. Univ. of Petroleum Dongying 257061 China

Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.

关键词： TFDC model atom phase diagram two-atoms model electron density atomic radius.

A New hcp Phase Formed in the Ni-Nb System during Ion-beam-assisted Deposition

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Journal of mat.rials Science & Technology 2004年第5期20卷 577-579页

作者： Bin ZHAO, Kuiwei GENG, Fei ZENG and Feng PANLaboratory of Advanced mat.rials, Department of mat.rials Science and Engineering, Tsinghua University, Beijing 100084, China Lab. of Adv. mat. Dept. of Mat. Sci. and Eng. Tsinghua Univ. Beijing 100084 China

The Ni80Nb20 films were prepared by ion beam assisted deposition (IBAD) with various Ar+ ion energies. A phase evolution of fcc→amorphous→Ni+Nb→Ni+hcp was observed with the increasing of ion beam energy from 2 keV to 8 keV. When bombarded by Ar+ ions of 8 keV during deposition, a new crystalline phase with hcp structure was obtained, of which the lattice parameters are a=0.286 nm and c=0.483 nm, different from those of the similar A3B-type hcp phase previously reported. The experimental res.lts were discussed in terms of thermodynamics and res.ricted kinetic conditions in the far-from-equilibrium process of IBAD. The format.on of hep phase may also be related to the valence electron effect.

关键词： Hcp phase Ni-Nb Ion beam assisted deposition Thermodynamics Valence electron effect

Influences of Yttrium on Microstructure and Mechanical Properties of NiAl-28Cr-5.5Mo-0.5Hf Alloy

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Journal of Rare Earths 2002年第4期20卷 295-298页

作者：任维丽郭建亭周继扬 dept. of mat. Eng. Dalian Univ. of Technol. Dalian 116024 China Inst. of Metal res. Chinese Acad. of Sci. Shenyang 110016 China

The influences of yttrium on the microstructure and mechanical properties of NiAl-28Cr-5.5Mo-0.5Hf alloy were investigated by using SEM, XRD and compres.ive tests, res.ectively. The study indicates that the compres.ive strength and ductility of 0.05% Y(mass fraction)-containing alloy are superior to those of other alloys at the strain rate of 1.94×10 -3 s -1 over a range from room temperature to high temperature. It is also found that the microstructure of alloys is refined gradually with increasing Y content. This is reflected by more grain cells, finer spacing between Cr(Mo) fibers and smaller Cr(Mo) rods at the grain boundary. When 0.1% Y(mass fraction) and above are added to the mat.ix, the yttrious compounds of Y 2Ni 17 and Al 3Y form at the interfaces between NiAl and Cr(Mo) phases, which leads to the decrease of strength and ductility. Therefore, the proper addition of Y can improve the compres.ive strength and ductility of the alloy.

关键词： rare earths NiAl alloy microstructure mechanical properties