Microstructural characterization of nanostructured Al2O3-ZrO2 eutectic layer by laser rapid solidification method
Autor: | Abdelkhalek Henniche, Yang Wang, Yong-Hui Ma, Zhi-Gang Wang, Ling-Yun Xie, Zhan-Guo Liu, Yujin Wang, Jia-Hu Ouyang |
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Rok vydání: | 2019 |
Předmět: |
Materials science
Laser scanning Scanning electron microscope General Physics and Astronomy 02 engineering and technology Surfaces and Interfaces General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films symbols.namesake Phase (matter) visual_art visual_art.visual_art_medium symbols Ceramic Laser power scaling Composite material 0210 nano-technology Raman spectroscopy Eutectic system |
Zdroj: | Applied Surface Science. 476:335-341 |
ISSN: | 0169-4332 |
Popis: | In the present work, nanostructured surface layers of Al2O3-ZrO2 eutectic with a thickness of approximate 1000 μm and free of cracks and pores were produced on the surface of conventionally-sintered Al2O3-ZrO2 ceramic via the laser irradiation rapid solidification process. The molten pool geometry and microstructure were characterized by scanning electron microscopy and Raman spectroscopy. The geometrical evolution of molten pool in response to laser power and laser scanning velocity was established, where the top view of molten pool exhibits a circular shape at low velocities and gradually evolves into an oval-shaped surface at high velocities. Singular Al2O3-ZrO2 eutectic colonies with a size of 100–200 μm, which is formed around a spontaneously nucleated dendritic ZrO2 core, are found on the surface of laser-remelted layer. The eutectic colony has an interphase spacing of 190–280 nm. The variation of eutectic spacing with growth rate is essentially linear on the logarithmic scale as λ = K V - 0.4 by binary regression analysis. Predicted by the Jackson-Hunt theory on eutectic solidification (JH theory), the eutectic spacing is consistent with the inverse-square-root dependence on growth rate with a proportionality constant of 3.32. The eutectic colonies consist of α-Al2O3, t-ZrO2 and m-ZrO2 phases, where α-Al2O3 and t-ZrO2 are the dominant phases and the m-ZrO2 phase increases with the decrease of laser scanning velocity. |
Databáze: | OpenAIRE |
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