Production of Undercooled Melt by Heating the Metastable Al2O3-YAP Eutectic Structure
Production of Undercooled Melt by Heating the Metastable Al2O3-YAP Eutectic Structure
复制标题
亚稳Al2O3-YAP共晶结构加热制备过冷熔体
DOI：
10.2320/matertrans.42.2124
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发表时间：
2001
影响因子：
1.2
通讯作者：
Y. Waku
中科院分区：
文献类型：
--
作者：
H. Yasuda;Y. Mizutani;I. Ohnaka;A. Sugiyama;Y. Waku
本文研究了al2o3 -YAG体系中亚稳共晶结构在加热过程中形成过冷熔体。加热/冷却过程中的相变由光学DTA设备检测。首先，将熔体加热至2273 K以上，凝固得到Al 2o3 -YAP亚稳共晶组织。当将由晶相组成的Al 2o3 -YAP亚稳共晶结构加热到高于平衡共晶组成（18.5 mol% y2o3）和亚稳共晶组成（23.5 mol% y2o3）的亚稳共晶温度时，证实了过冷熔体的形成。对于18.5 mol%的y2o3试样，过冷熔体形成后立即在al2o3 -YAG平衡路径上凝固。对于23.5 mol%的y2o3试样，得到的过冷熔体保持均匀长达3600 s而不凝固。在熔化和凝固同时进行时，得到了细小均匀的Al 2o3 -YAG共晶组织。在吸热熔化的同时，放热凝固对潜热的放热释放有很大的好处。因此，在非共晶成分中，高生长速率导致了细小的共晶结构。
This paper demonstrates the undercooled melt formation from the metastable eutectic structure by heating procedures in the Al 2 O 3 -YAG system. Phase transformation during heating/cooling procedures is detected by optical DTA equipment. Firstly, the Al 2 O 3 -YAP metastable eutectic structure is obtained by solidification after heating the melt above 2273 K. The undercooled melt formation is confirmed when the Al 2 O 3 -YAP metastable eutectic structure composed of crystalline phases is heated up to temperatures above the metastable eutectic temperature for the equilibrium eutectic composition (18.5 mol% Y 2 O 3 ) and the metastable eutectic composition (23.5 mol% Y 2 O 3 ). The undercooled melt formation is immediately followed by the solidification in the Al 2 O 3 -YAG equilibrium path for the 18.5 mol% Y 2 O 3 specimens. For the 23.5 mol% Y 2 O 3 specimens, the obtained undercooled melt is kept even for as long as 3600 s without solidification. Furthermore, the fine and uniform Al 2 O 3 -YAG eutectic structure is obtained when the melting and the solidification simultaneously occur. The solidification with the exothermic heat beside the melting with the endothermic heat has a great advantage for heat release of the latent heat. Consequently, the high growth rate leads to the fine eutectic structure in the off-eutectic composition.