WANG Ruikun SUN Lihong LI Dongpei YING Qiming T.Takeyama General Research Institute for Non-Ferrous Metals
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Beijing
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China [Originally published in ACTA METALL SIN (CHINESE EDN) 24 (5) 1988 pp B353—B358
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received 6 May 1987
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in revised form 6 February 1988] T.Takeyama is an emeritus professor of HOKKAIDO University
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Japan
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and now is a technical adviser of GRINFM
金属学报(英文版)
The magnetic domain structure and related magnetic properties of (NdPr)_(16)Fe_(76)B_8 permanent magnet have been studied by colloid-SEM method.In thermally demagnetized state,the ma- trix grains in the magnet generally exhibit multidomain structure,i.e.,180° plate-like indi- vidual domain and a few spike-like or maze-like domains.The average width of the domain measured was 1.5μm.Grain size of single-domain was observed to be generally about 1μm and only a few up to 3μm.The results calculated are:the domain wall energy γ=36 MJ/m~2,the exchange constant A=4.5×10~(-11)J/m,the domain wall width δ=15.7nm, and the critical grain diameter of single-domain D_c=0.5μm.The dependence of high magnet- ic field gradient at grain boundaries in different magnetization directions in the adjacent mag- netic domains located on both sides of grain boundaries and the effect of microstructure on the values of K,A and δ were discussed.
关键词:
Nd-Fe-B permanent magnet
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null
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null
Acta Materialia
An analytical relationship between the ratio of hardness to reduced modulus H/E-r and the geometry of a residual indent is established based on the theories of depth-sensing indentation. Various material parameters, including elastic parameters, recovery deformation and energy-dissipation capacity, are uniquely determined by the value of H/E-r, so that they can be estimated from a residual indent trail. Thus, we are able to know what has happened in the material simply by analyzing or comparing residual trails on the material. The validity of this method has been confirmed by analyzing residual Vickers indents on quasi-plastic ceramic and brittle glass. In addition, it is demonstrated that the geometric constant epsilon in traditional nanoindentation theories is related to the proportional factor eta through the exponent of unloading curve m, i.e., epsilon = m (.) eta, where eta is defined by h(s) = eta (.) (h(m) - h(f)). (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
residual indent;Vickers indenter;property prediction;H/E-r ratio;depth-sensing indentation;instrumented indentation;mechanical-properties;nanoindentation;modulus;hardness;deformation;films;load;substrate
Wenbin XUE
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Chao WANG
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Zhiwei DENG
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Ruyi CHEN
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Tonghe ZHANG
材料科学技术（英文）
Dense ceramic oxide coatings of about 50 μm may be prepared on Ti-6Al-4V alloy surface by alternating-current microarc oxidation in aluminate and silicate solutions, respectively. Their phase constituent and microstructure were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the electrolytic ions have incorporated into the interior of the coatings. The coating formed in aluminate solution is composed of the rutile TiO2 and TiAl2O5 phases rather than the rutile, anatase and amorphous SiO2 phases for the coating formed in silicate solution. However, TiAl¬2O5 content in the outer layer of the two coatings is much higher than in the inner layer. It is suggested that all these oxides may result from a rapid solidification of the molten coating in the microarc discharge zone.
关键词:
Microarc oxidation
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null
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