Abstract Directionally solidified eutectic oxide ceramics are very promising as a next-generation structural material for ultrahigh-temperature applications, above 1600 °C, owing to their outstanding properties of high corrosion resistance, oxidation resistance, high fracture strength and toughness, and high hardness. Herein, Al2O3/GdAlO3 eutectic ceramic was prepared with horizontal high-frequency induction zone melting (HIZM), and the effects of the processing parameters on the eutectic microstructure and mechanical properties were investigated. The results indicated that the directionally solidified Al2O3/GdAlO3 eutectic ceramic was composed only of the Al2O3 phase and GdAlO3 phase penetrating mutually, and the Al2O3 phase was the substrate in which the GdAlO3 phase was embedded. As the solidification rate increased from 1 to 5 mm/h, the eutectic microstructure underwent a transformation from an irregular pattern to a relatively regular “rod” or “lamellar” pattern, and the eutectic spacing constantly decreased, reaching a minimum value of 0.5 μm. The eutectic ceramic hardness and fracture toughness at room temperature increased continuously, reaching 23.36 GPa and 3.12 MPa•m1/2, which were 2.3 times and 2.5 times those of the sintered ceramic with the same composition, respectively. Compared with the samples obtained from vertical high-frequency induction zone melting, the orientation of eutectic phases along the growth direction decreased significantly, and the size uniformity of the GdAlO3 phase became poorer in the samples prepared with HIZM at the same solidification rate; nevertheless, the hardness and fracture toughness of the samples increased by 11% and 63%, respectively.

中文翻译：

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水平高频区熔制备定向凝固Al2O3/GdAlO3共晶陶瓷的组织和力学性能

摘要 定向凝固共晶氧化物陶瓷由于具有高耐腐蚀性、抗氧化性、高断裂强度和韧性以及高硬度等优异性能，作为下一代超高温应用（1600℃以上）结构材料非常有前景。在此，采用水平高频感应区熔法（HIZM）制备了Al2O3/GdAlO3共晶陶瓷，并研究了工艺参数对共晶组织和力学性能的影响。结果表明，定向凝固的Al2O3/GdAlO3共晶陶瓷仅由Al2O3相和GdAlO3相相互渗透组成，Al2O3相是嵌入GdAlO3相的基体。随着凝固速度从 1 增加到 5 mm/h，共晶组织经历了从不规则图案向相对规则的“棒状”或“层状”图案转变，共晶间距不断减小，最小值达到0.5μm。共晶陶瓷的室温硬度和断裂韧性不断提高，分别达到23.36 GPa和3.12 MPa•m1/2，分别是相同成分烧结陶瓷的2.3倍和2.5倍。与垂直高频感应区熔炼得到的样品相比，在相同凝固速率下用HIZM制备的样品中，共晶相沿生长方向的取向显着降低，GdAlO3相的尺寸均匀性变差；尽管如此，样品的硬度和断裂韧性提高了 11% 和 63%，