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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 16    No. 2    April 2006

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Microstructure and property of sub-micro WC-10 %Co particulate reinforced Cu matrix composites prepared by selective laser sintering
GU Dong-dong(顾冬冬)1, SHEN Yi-fu(沈以赴)1, DAI Peng(代 鹏)1, YANG Ming-chuan(杨明川)2

1. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China;
2. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

Abstract:The WC-10%Co particulate reinforced Cu matrix composite material with a WC-Co∶Cu mass ratio of 20∶80 was successfully fabricated by selective laser sintering(SLS) process. The following optimal processing parameters were used: laser power of 700 W, scan speed of 0.06 m/s, scan line spacing of 0.15 mm, and powder layer thickness of 0.3 mm. The microstructure, composition, and phase of the laser processed material were investigated by scanning electron microscopy(SEM), X-ray diffraction(XRD), and energy dispersive X-ray(EDX) spectroscopy. The results show that the bonding mechanism of this process is liquid phase sintering. The Cu and Co act as the binder phase, while the WC acts as the reinforcing phase. The non-equilibrium effects induced by laser melting, such as high degrees of undercooling and high solidification rate, result in the formation of a metastable phase CoC0.25. The WC reinforcing particulates typically have three kinds of morphology. They are agglomerated and undissolved, incompletely separated and partially dissolved, separated and dissolved, which indicates that particle rearrangement acts as the dominant sintering mechanism for the larger WC, while dissolution-precipitation prevails for the smaller WC particles. Microhardness tester was used to determine the Vickers hardness across the cross-section of the laser sintered sample, with the average value being HV0.1268.5. However, the hardness varied considerably, which might be attributed to the WC segregation and the high solidification rate experienced by the molten pool.

 

Key words: selective laser sintering; metal matrix composites; Cu matrix composite; WC-Co; Cu; microstructure; microhardness

ISSN 1672-7029
CN 43-1423/U

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