Microstructures and mechanical properties of directionally solidified Al₂O₃/GdAlO₃ eutectic ceramic by laser floating zone melting with high temperature gradient

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• 作者：Haijun Su^a ; ^{shjnpu@nwpu.edu.cn} ; Qun Ren^a ; Jun Zhang^a ; Kaichen Wei^a ; Bin Yao^a ; Weidan Ma^a ; Guangrao Fan^a ; Min Guo^a ; Lin Liu^a ; He Bai^b ; Hengzhi Fu^a
• 关键词：Directionally solidified eutectic ; Microstructure ; Mechanical properties ; Oxide ceramics ; Solidification behaviour
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：37
• 期：4
• 页码：1617-1626
• 全文大小：4749 K
• 卷排序：37

文摘

Directionally solidified Al2O3/GdAlO3 eutectic ceramic rods with high densities and low solidification defects are prepared by laser floating zone melting at solidification rate from 2 to 200 μm/s. The microstructure evolution, eutectic growth behavior and mechanical properties are investigated. At low solidification rates (<30 μm/s), the eutectic rods present a homogeneous irregular eutectic microstructure, whereas cellular microstructure containing regular lamella/rod structure is developed at higher solidification rates. The relationship is established between the eutectic interphase spacing and solidification rate, which follows the Magnin-Kurz eutectic model. The Vickers hardness (15.9–17.3 GPa) increases slightly with decreasing interphase spacing, but the fracture toughness (4.08 MPa m1/2) shows little dependence with the solidification rate. Different crack propagation mechanisms are revealed among the indentation cracks. The flexural strength at ambient temperature reaches up to 1.14 GPa for the eutectic grown at 100 μm/s. The fracture surface analysis indicates that the surface defects are the main crack source.