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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 11    No. 4    August 2001

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Structure of nanocrystalline WC-10%Co powder
YANG Zhi-min(杨志民)1, MAO Chang-hui(毛昌辉)1, DU Jun(杜 军)1
Michel Daniel2, Champion Yannick2, Hagège Serge2, Hytch Martin

1. General Research Institute for Nonferrous Metals,
Beijing 100088, P.R.China;
2. Centre d'Etudes de Chimie Métallurgique/CNRS,
94407 Vitry-sur-Seine, France

Abstract:Nanostructured WC-Co powders obtained by mechanical milling were investigated by combination of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) techniques. Rietveld analysis indicates that the experimental XRD patterns cannot be satisfactorily explained with the hexagonal WC structure. HRTEM image analysis shows that in the as-milled nanostructured powder, many WC grains contain stacking faults lying on the plane {10·0}. Analysis of phase images show that these defects are nearly periodically ordered along the [10·0]direction. Based on these observations, a structural model was proposed for the WC grains with ordered stacking faults, which is in fact equivalent to a superstructure of WC with space group Amm2. When this model describing the faulted fraction of WC is introduced together with the normal WC structure (space group P 6 ̄m2) into the Rietveld refinement, a much better agreement between the calculated and experimental XRD profiles was obtained. This study allows to obtain the lattice parameters, grain size, microstrain and other structural information on the as-milled powders.

 

Key words: structural properties; mechanical milling; WC-Co

ISSN 1672-7029
CN 43-1423/U

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