Microstructure tailoring and thermal stability of directionally solidified Al2O3/GdAlO3 binary eutectic ceramics by laser floating zone melting
Microstructure tailoring and thermal stability of directionally solidified Al2O3/GdAlO3 binary eutectic ceramics by laser floating zone melting
复制标题
激光浮区熔炼定向凝固 Al2O3/GdAlO3 二元共晶陶瓷的微观结构和热稳定性
DOI：
10.1016/j.ceramint.2018.01.228
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发表时间：
2018
影响因子：
5.2
通讯作者：
Hengzhi Fu
中科院分区：
文献类型：
--
作者：
Haijun Su;Enyuan Wang;Qun Ren;Haifang Liu;Di Zhao;Guangyao Fan;Jun Zhang;Lin Liu;Hengzhi Fu
采用激光浮区熔融法制备了Al2O3/ gdalo3定向凝固共晶复合陶瓷，具有较低的凝固缺陷，使其具有均匀的组织和高温梯度下的热稳定性。在低凝固速率下，凝固组织呈现出粗大的群体组织和均匀的“汉字”不规则共晶组织并存的周期性生长条形组织。生长条纹间隔和凝固速率遵循l /V=（238.8±2.4） s的关系。通过进一步优化激光加工参数，使共晶间距大大细化到亚微米尺度，并消除了高凝固速率下的组织振荡，通过多面共晶转变获得了完全规则的片层/棒状共晶结构。棒状共晶间距（λ）与凝固速率(V)遵循λ·V1/2= 6.21 µm3/2s−1/2的线性关系。此外，在1500 °C下加热250 h后，固化共晶复合材料即使具有细小的共晶结构，也表现出优异的热稳定性。
Directionally solidified Al2O3/GdAlO3eutectic composite ceramics with low solidification defects are prepared by laser floating zone melting to tailor homogeneous microstructure and thermal stability performance under high temperature gradient. At low solidification rate, the solidification microstructure shows periodical growth striations in which coarse colony microstructure and homogeneous ‘Chinese script’ irregular eutectic structure are coexisted. The growth striation intervalLand solidification rateVfollow the relationship ofL/V= (238.8 ± 2.4) s. By further optimizing laser processing parameters, the eutectic spacing is greatly refined to submicron scale and microstructure oscillation is eliminated at high solidification rates, and fully regular lamellar/rod eutectic structures are obtained by faceted eutectic transition. The rod-like eutectic spacing (λ) and solidification rate (V) follow the linear relationship ofλ·V1/2= 6.21 µm3/2s−1/2. Furthermore, the as-solidified eutectic composite even with fine eutectic structure exhibits excellent thermal stability after heat exposure at 1500 °C for 250 h.