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STUDY OF THE EFFECT OF BORON CONTENT ON THE ORDERED EXTENT OF THE Ni_3Al INTERMETALLICS COMPOUND BY ap-fim

Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 1001-1011页

作者： D.G. Ren Z.Q. Li X.S. Fan and J. T. Guo Laboratory of Atomic Imaging of Solids, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110015, China Inst of Metal Research Chinese Acad of Sciences Shenyang China

By using ap-fim the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.

关键词： intermetallic compound ap-fim effect of boron

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ap-fim STUDY ON THE MICROSTRUCTURES OF TiAlINTERMETALLIC COMPOUNDS FXBRICATED BY INGOTMETALLURGY AND CENTRIFUGAL SPRAY DEPOSITION

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Acta Metallurgica Sinica(English Letters) 2000年第6期13卷 1165-1173页

作者： D.G. Ren, W.Z. Chen and X.S. Fan ( Laboratory of Atomic Imaging of Solids, Institute of Metal Research, The Chinese Academy of Sciences,Shenyang 110015, China College of Materials Science and Engineering, Fuzhou University, Fuzhou 350002, China)

The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (ap-fim). The samples used have nearly stoichiometric composition of TiAl but there is Mn addition for ingot metallurgy (IM) samples and Mn and Nb additions for CSD samples. The field ion image of TiAl showed two regions of ordered f.c.t crystal structure (γ-TiAl) and disordered α-Ti3Al, and the distribution of Ti and Al atoms in TiAl alloy showed a lamellar structure which was confirmed by ap profiles. ap profiles showed that the major constituent of IM TiAl alloy is γ-TiAl with some Ti-rich regions. The compositions of these Ti-rich regions are nearly Ti3Al and Ti2Al from the calculation of ap data. The sample of CSD has a similar microstructure as compared with IM sample. The effects of alloying elements (Mn and Nb) on the ordering extent ,their distribution, and their sites occupied in the lattice were explored for both TiAl alloys. But there are no obvious Ti3Al or Ti2Al phases as shown in IM sample. In addition, the distributions of Mn and Nb concentrations in the CSD sample have a characteristic of wave form.

关键词： intermetallic compound microstructure ap-fim

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THE EXPERIMENTAL STUDIES OF NiO CLUSTER FORMATION INNi_3Al ALLOYS BY ap-fim

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Acta Metallurgica Sinica(English Letters) 2000年第6期13卷 1159-1164页

作者： D.G. Ren and X.S. Fan (Laboratory of Atomic Imaging of Solids, Institute of Metal Research, The Chinese Academy of Sciences,Shenyang 110015, China)

The purpose of the present work is to study the NiO cluster formation in Ni3Al alloys by field ion microscope and atom probe (ap-fim). A polycrystal Ni3Al (B-doped) was heat-treated in atmospheres, the surface adsorption of air (hydrogen, oxygen) moisture etc.) occured on the Ni3Al surface and then these absorbents diffused into the interior of alloy through groin boundaries. ap-fim studies found that the NiO and AlO clusters appeared in the local regions and amount of NiO clusters is much more than that of AlO. Moreover the hydrogen was simultaneously detected in the identical *** results provided an experimental evidence that the formation of NiO and AlO clusters is the result of reaction of Ni (or Al) with residual moisture in Ni3Al, i.e. Ni+H2 O→NiO+2H. But the samples of B-free Ni3Al and B-doped single crystal Ni3Al have low concentration of NiO and H. This result shows that the diffusion of H2O molecule was promoted by genie boundaries containing boron. In addition, the boron suppresses environmental emvironmental was discussed, which suggested that the formation of Ni-O bonding has influence on bonding character of Ni-Al atoms and benefits the ductility of alloy.

关键词： Ni-3Al alloy NiO cluster ap-fim

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ap-fim研究磁性材料微结构

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电子显微学报 1988年第4期 53-57页

作者：任大刚刘治国中国科学院金属研究所南京大学物理系沈阳

场离子显微镜（fim）是一种具有高分辨高放大倍数且能直接观察到固体表面单个原子的技术,将fim与飞行时间质谱计配合构成原子探针——场离子显微镜（ap-F;M）可鉴别极微区域（几nm）的化学成份,因此是研究材料微结构的有力工具。本文用A... 详细信息

场离子显微镜（fim）是一种具有高分辨高放大倍数且能直接观察到固体表面单个原子的技术,将fim与飞行时间质谱计配合构成原子探针——场离子显微镜（ap-F;M）可鉴别极微区域（几nm）的化学成份,因此是研究材料微结构的有力工具。本文用ap-fim研究了Al-Ni-Co永磁材料的微结构。用场离子显微镜观察了合金中沉淀相的形貌并用原子探针测定了不同沉淀相的化学成份及数量合金元素在沉淀相中分布。结果表明,合金中存在富铝相,富镍-钴相铁-钴-镍桐,少量Ce及Cu分布在富镍-钴相中。

关键词：沉淀相离子 Ni 化学成份 Cu ap-fim 磁性材料电工材料 fim 微结构土壤结构

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