Abstract To obtain improved mould shells with appropriate microstructures for directional solidification casting of NbSi-based alloys, Y2O3 ceramics with various microstructures were designed and characterized. The mechanisms of high-temperature wettability and interactions between NbSi-based alloys and Y2O3 ceramics were studied. The results showed that there was a characteristic transition in the wettability between the molten alloys and ceramics when the Y2O3 microstructure changed. The spreading rate gradually decreased and the apparent equilibrium contact angle changed from 70.2° to 112.6° with the level of open porosity of Y2O3 ceramics increasing from 3.6% to 27.2%. Wetting kinetics analyses indicated that the movement of the triple line during the wetting process was driven by the formation of continuous HfO2 reaction layer in the alloy-ceramic interface. The content of HfO2 particles inner the alloy matrix with the level of open porosity of Y2O3 ceramics increasing from 3.6% to 27.2% initially gradually decreased and subsequently increased. Y2O3 with open porosity level of about 20.7% were the most beneficial for directional solidification casting of high-purity Hf-containing NbSi-based alloys.

中文翻译：

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含 Hf 的 NbSi 基合金与具有不同微观结构的 Y 2 O 3 陶瓷之间的高温润湿性和相互作用

摘要 为了获得用于NbSi 基合金定向凝固铸造的具有合适显微组织的改进型壳，设计并表征了具有各种显微组织的Y2O3 陶瓷。研究了 NbSi 基合金与 Y2O3 陶瓷之间的高温润湿性和相互作用机制。结果表明，当Y2O3微观结构发生变化时，熔融合金与陶瓷之间的润湿性发生了特征性转变。随着Y2O3陶瓷的开孔率从3.6%增加到27.2%，铺展率逐渐降低，表观平衡接触角从70.2°变为112.6°。润湿动力学分析表明，在润湿过程中三重线的运动是由合金-陶瓷界面中连续 HfO2 反应层的形成驱动的。随着Y2O3陶瓷的开孔率从3.6%增加到27.2%，合金基体内部HfO2颗粒的含量逐渐降低，随后增加。开孔率约为 20.7% 的 Y2O3 最有利于高纯度含 Hf 的 NbSi 基合金的定向凝固铸造。