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Microstructure of Al2O3 nanocrystalline/cobalt-based alloy composite coatings by laser deposition
AbstractComposite coatings, made of nano-Al2O3/cobalt-based alloy, produced by a 5-kW CO2 laser on Ni-based superalloy were investigated. The coatings were examined to reveal their microstructure using optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffraction instrument. The results showed that some equilibrium or non-equilibrium phases, such as γ-Co, Cr23C6, CoAl2O4, Al2O3 and &z.epsiv;-Co existed in the coatings. Fine and short dendritic microstructure and columnar to equiaxed transition occurred by adding nano-Al2O3 particle. With the increase of nano-materials (1%, mass fraction), fully equiaxed crystallization appeared. These were contributed to that nano-Al2O3 particles acted as new nucleation site and rapid solidification of the melted pool. The results also showed inhomogeneous dispersion of nano-Al2O3 that resulted in the formation of &z.epsiv;-Co phase in the coatings. The sub-microstructure of the clad was stacking fault. The mechanism of formation of equiaxed grains was also analyzed.
Microstructure of Al2O3 nanocrystalline/cobalt-based alloy composite coatings by laser deposition
AbstractComposite coatings, made of nano-Al2O3/cobalt-based alloy, produced by a 5-kW CO2 laser on Ni-based superalloy were investigated. The coatings were examined to reveal their microstructure using optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffraction instrument. The results showed that some equilibrium or non-equilibrium phases, such as γ-Co, Cr23C6, CoAl2O4, Al2O3 and &z.epsiv;-Co existed in the coatings. Fine and short dendritic microstructure and columnar to equiaxed transition occurred by adding nano-Al2O3 particle. With the increase of nano-materials (1%, mass fraction), fully equiaxed crystallization appeared. These were contributed to that nano-Al2O3 particles acted as new nucleation site and rapid solidification of the melted pool. The results also showed inhomogeneous dispersion of nano-Al2O3 that resulted in the formation of &z.epsiv;-Co phase in the coatings. The sub-microstructure of the clad was stacking fault. The mechanism of formation of equiaxed grains was also analyzed.
Microstructure of Al2O3 nanocrystalline/cobalt-based alloy composite coatings by laser deposition
Li, Mingxi (author) / He, Yizhu (author) / Yuan, Xiaomin (author) / Zhang, Shihong (author)
2005-03-23
6 pages
Article (Journal)
Electronic Resource
English
Microstructure of Al2O3 nanocrystalline/cobalt-based alloy composite coatings by laser deposition
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