Preparation and microstructure evolution of directionally solidified Al2O3/YAG/YSZ ternary eutectic ceramics by a modified electron beam floating zone melting
Preparation and microstructure evolution of directionally solidified Al2O3/YAG/YSZ ternary eutectic ceramics by a modified electron beam floating zone melting
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DOI：
10.1016/j.matlet.2012.09.064
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发表时间：
2013-01
影响因子：
3
通讯作者：
H. Su;Jun Zhang;Lin Liu;H. Fu
中科院分区：
文献类型：
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作者：
H. Su;Jun Zhang;Lin Liu;H. Fu
报道了利用改进的高温度梯度电子束浮区熔炼技术首次制备了Al_2O_3/YAG/YSZ三元共晶自生复相陶瓷。在优化的凝固条件下，获得了直径为2~4 mm、长度可达50 mm的高密度(99.5%)Al_2O_3/YAG/YSZ块体共晶陶瓷棒。在低速率下，生长的复相陶瓷在稳定生长区内呈现出沿生长方向高度择优取向的不规则共晶片层，由均匀分布的亚微米级的Al_2O_3、Y_2O_3和Y_2O_3相组成。在初始生长区，倾向于形成具有较强刻面特征的粗大初生Al_2O_3或YAG相。随着凝固速度V的增加，相尺寸和平均相间间距λ迅速减小，在V<；90 mm/h符合λ2V=常数关系，在较高的凝固速率下形成胞内区规则片层的胞状共晶组织。
We report the first growth of Al2O3/YAG/YSZ ternary eutectic in-situ composite ceramics by a modified electron beam floating zone melting technique with high temperature gradient. At optimized solidification conditions, high density (>99.5%) Al2O3/YAG/YSZ bulk eutectic ceramic rods with diameter of 2–4mm and length up to 50mm are successfully obtained. The grown composite ceramics present highly aligned irregular eutectic lamellae parallel to growth direction in stable growth zone at low rates, consisting of homogeneously distributed Al2O3, YAG and YSZ phases in the submicron size. The coarse primary Al2O3or YAG phases with strong faceted characteristic are preferred to form in the initial growth zone. The phase size and mean interphase spacing λ rapidly decrease with increasing solidification rate V where the relationship λ2V=constant is obeyed at V<90mm/h. The cellular eutectic structures with regular lamellae in the intra-cellular region are produced at high growth rate.