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HREM Study on Sm(Co,Fe,Cu,Ti)_7 Alloy Aged under Different Conditions

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Journal of Rare Earths 1996年第4期14卷 250-256页

作者：刘安生 General Research Institute for Non-ferrous Metals Beijing 100088 China Institute for Materials Research Tohoku University Sendai 980 Japan

The microstructures and defects of various aged Sm( Co, Fe,Cu,Ti)_7 alloys have been observed in several orientations by using high resolution electron *** results indicate that the alloy is composed of Sm2(Co,Fe,Cu,Ti)_(17)(2:17) phase with a small amount of titanium and Sm(Co,Fe,Cu)5,(1:5) *** 2:17 phase is rich in iron and the 1.5 phase is rich in *** aging stages corresponding to the peak magnetic coercivity,the alloy has a cellular-like microstructure with fine cells of the 2:17 phase surrounded by thin boundaries of the 1:5 *** average size of the cells is about 33 *** orientation relationship of [0001]_(2:17)/[0001]1:5 and(1210)_(2:17)/(0110)_(1:5) has been found in this *** high resolution images show coherence between 2:17 phase and 1:5 phase and very small mismatch in some phase *** cells of 2:17 phase are full of microtwins with twin plane perpendicular to *** cells of 2:17 phase rapidly grow up,when the aging temperature rises and aging time *** the alloy aged at 850℃, the 2:17 phase and 1:5 phase transform from cellular-like into striplike microstructure,and a few of twin boundaries can be seen in the 2:17 *** the twin boundaries,antiphase boundaries are sometimes observed in the 2:17 phase of the alloy aged at 800℃,for 10 h.

关键词： Permanent magnet Sm-Co alloy Microstructure Defects high resolution electron microscopy

FINE STRUCTURES OF BOTH INTERFACES AND INTERFACIAL REACTION PRODUCTS

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Acta Metallurgica Sinica(English Letters) 1993年第1期6卷 1-20页

作者： LI Douxing PING Dehai NING Xiaoguang YE Hengqiang Laboratory of Atomic Imaging of Solids,Institute of Metal Research,Academia Sinica,Shenyang.China Professor,Institute of Metal Research,Academia Sinica,Shenyang 110015,China Inst of Metal Research Acad Sinica Shenyang China

The characteristic of interface depending on the atomic structure exerts an inportant,and sometime controlling,influence on performance of the interacial materials. The present paper reviews the main studies on fine structure of both the materials inter- faces and interfacial reaction products in semiconductor uperlattice,metal multilayer ceram- ics and composite materials by mean of selected area electron doffraction patterns and high resolution electron microscopy. The following features of interfaces are reviewed:the orientation relationships;the char- acteristic of steps,facets and ronghness of interfaces;atomic bonding across the interface;the degree of coherency,the structure of misfit dislocations and elastic relaxations at the inter- faces:the presence of defects at the onterfaces:the structure of the interfacial reaction prod- ucts as well as the reaction kinetics and reaetion mechanism.

关键词： fine structure of the interfaces interfacial solid state reaction orientation relationship high resolution electron microscopy

ATOMIC SCALE MECHANISM OF RESTRAINED EMBRITTLEMENT IN AMORPHOUS Fe_(78)B_(13)Si_9 ALLOY BY ELECTRIC PULSE RAPID ANNEALING

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Acta Metallurgica Sinica(English Letters) 1998年第4期11卷 286-290页

作者： J.L. Huang X.G. Cao E. Sukedai S. Yamasaki and H.C.Gu(Department of Materials Engineering, Luoyang Institute of Technology, Luoyang 471039, China)(Department of Mechanical Engineering, Okayama University of Science, 1-1 Ridai-Cho,Okayama City,Okayma Luoyang Inst of Technology Luoyang China

The direct observations of the atomic arrangements in both conventional furnace annealed and electric pulse rapid annealed Fe78B13Si9 amorphous alloy have been conducted by the lattice imaging technique in a higt resolution electron microscope. The results showed that the embrittlement of the alloy was related to the extent of atomic rearrangements during the annealing processes. The embrittlement of the alloy after 1hour conventional furnace annealing at about 270℃ is caused by the sufficient atomic rearrangements which are characterized by the growth of some bct Fe3B-like atomic short range ordering regions already existed in the as-quenched structure. Electric pulse rapid annealing can effectively retard the above-mentioned atomic rearrangements and thus restrain the embrittlement. The embrittlement only occurs when certain amount of bcc α-Fe nanocrystals are precipitated in the amorphous matrix during electric pulse rapid annealing.

关键词： Fe_(78)B_(13)Si_9 amorphous alloy embrittlement electric pulse rapid annealing high resolution electron microscopy

Nanometer Stripe Microstructure of Supersaturated Solid Solution in Fe-Cu Alloy

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Journal of Iron and Steel Research(International) 2007年第1期14卷 64-68页

作者： REN Hui-ping WANG Hai-yan LIU Zong-chang AN Zhi-guo College of Material and Metallurgy Engineering Inner Mongolia University of Science and TechnologyBaotou 014010 Inner Mongolia China

Strengthening due to precipitation of Cu in the a-Fe matrix is an important phenomenon utilized in the design of HSLA steels. In the present work, the microstructure of supersaturated solid solution in Fe-1.18%Cu binary alloy was investigated by means of high resolution electron microscopy. The results indicated that the solid solution was heterogeneous, there were lots of Cu atom clusters, which consisted of diffractive stripe microstructure similar to twin crystal. Orientation deviation was observed between two （110）o planes in diffractive stripes, which results in light and shade contrast. Furthermore, formation mechanisms of the nanometre stripe microstructure were discussed in terms of the interaction of Cu and Fe atoms in the Fe-Cu binary alloys.

关键词： Fe-Cu alloy supersaturated solid solution Cu-rich cluster nanometer stripe microstructure high resolution electron microscopy

HREM STUDY OF GRAIN BOUNDARY PHASES IN Fe-Ni-Co-Nb-Ti SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 595-600页

作者： R.M. Wang C.Z. Li S. W. Zhang and M.G.Yan(1)Institute of Aeronautical Materials, Beijing 100095, China 2)Laboratory of Atomic Imaging of Solids, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110015, China 3)Beijing Laboratory of Elect Beijing Inst of Aeronautical Materials Beijing China

The microstructures of the grain boundary phases in Fe-Ni-Co-Nb-Ti superalloy have been studied by high resolution electron microscopy (HREM).Besides the Laves phase,three other grain boundary phases have been found and analyzed. The ε phase particles are needle-like with some stacking faults along the(0001) direction. The dominant phase at the grain boundaries is the orthorhombic phase that is also rod-like. high reselution image also confirms the existence of the triclinic phase at the grain boundaries that is irregular and scarce.

关键词： high resolution electron microscopy grain boundary phase,FeNi- Co superalloy

Preparation of nanodiamonds by laser irradiation of graphite

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Chinese Optics Letters 2005年第5期3卷 287-288页

作者：孙景雷贻文翟琪杨星杨晶杜希文 School of Materials Science and Engineering Tianjin University Tianjin 300072

Graphite powders were irradiated by pulsed laser at room temperature and normal pressure and then boiled in perchloric acid. Samples were characterized by high-resolution transmission electron microscopy (HRTEM), electron diffraction pattern (EDP), X-ray diffraction (XRD) pattern, and Raman spectroscopy. The analyses on the HRTEM images, EDP, and XRD show that the diamond particles with a size of about 5 nm are obtained. The shifting and broadening of the diamond peak in Raman spectrum indicate that there are high defect density and residual internal stress in synthetic diamond.

关键词： Defects Graphite high resolution electron microscopy Laser beam effects Nanostructured materials Pulsed laser applications Raman spectroscopy Transmission electron microscopy X ray diffraction analysis

稀土Y对低膨胀高温合金显微组织和界面的影响(英文)

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Chinese Journal of Aeronautics 2001年第3期14卷 171-177页

作者： Wang, R.-M. Han, Y.-F. Eliezer, D. Beijing Inst. of Aeronautical Mat. P O. Box 8l-4 Beijing 100095 China

The forms and structures of the phases in Fe-Ni-Co-Nb-Ti-Si low expansion superal-loys have been studied using analytical electron microscopy, high resolution electron microscopy, chemical phase analysis, X-ray diffraction, etc. The effects of yttrium on the microstructures and properties in the superalloys have also been investigated. The results reveal that trace yttrium mainly located in the platelet precipitates makes the crystal structure changed. The platelet precipitates become smaller, denser and rather homogeneous with appropriate yttrium addition. Compared with the conventional low expansion superalloy, the misfit of the platelet phase with the matrix in the yttrium-containing low expansion superalloy decreases from 0.7% to 0.07%, which indicates very low stress at the interface.

关键词： Crystal structure high resolution electron microscopy Interfaces (materials) Microstructure Thermal expansion X ray diffraction analysis Yttrium

HRTEM Studies of the Ultrafme Structures of Interfaces

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Progress in Natural Science:Materials International 1994年第2期 65-77页

作者：李斗星 Academia Sinica Institute of Metal Research Laboratory of Atomic Imaging of Solids PRC Shenyang 110015

The present paper summarizes the recent researching results concerning the ultrafine structures of both material interfaces and interfacial reaction products in semiconductor superlattices, metal multilayers, ceramics and composite materials by the high resolution transmission electron microscopy (HRTEM). Various important features of interfaces are discussed, including the roughness of interfaces; the degree of coherency, the structure of misfit dislocation and elastic strain relaxations at the interfaces; the atomic structures of interfaces; the presence of defects at the interfaces; the structures of the interfacial reaction products, as v玌 as the reaction kinetics and mechanism.

关键词： high resolution electron microscopy intcrfacial structure interfacial solid state reaction.

An Approach to Structure Determination for Minute Crystals

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Progress in Natural Science:Materials International 1993年第5期 385-394页

作者：李方华 Institute of Physics Academia Sinica Beijing 100080 PRC

1 Introduction It is well known that the interaction of substances with electrons is much strongerthan that with X-rays. Since the 1950s electron diffraction has been used for crystal strut-ture determination of thin films. It is also successfully applied to crystal structuredetermination for some organic crystals. However, electron diffraction analysis suffers thesame phase problem as other diffraction techniques, namely only the amplitudes of dif-fracted waves are recorded in experiments, while the phases are lost. Since the 1970s the development of high resolution electron microscopy(HREM)has provided an approach to crystal structure determination for minute crystals. A highresolution electron microscope image taken under the Scherzer defocus condition reveals

关键词： high resolution electron microscopy electron diffraction image deconvolution phase extension