层状共晶定向凝固

本文从理论和实验两方面研究层状共晶定向凝固。理论上将层状共晶定向凝固与胞晶列定向凝固及Hele-Shaw胞中粘性指发展进行类比,给出层状共晶稳态凝固条件下溶质扩散、热传输与界面张力效应之间的耦合系,导出λ²ν=consi标度关系。实验上考察了规则Al-Al₂Cu共晶和非规则Al-Si共晶定向凝固,证实耦合关系存在。还讨论了两种共晶凝固界面特征和热传输的影响。 关键词：

DIRECTIONAL SOLIDIFICATION OF LAMELLAR EUTECTIC

Directional solidification of lamellar eutectic has been studied both theoretically and experimentally. This process has been modeled through comparing it with directional solidification of an array of cells in binary alloys and developing of the Saffman-Taylor viscous fin-gerinig in a Hele-Shaw cell in an unitied framework. A coupling relation among the solute diffusion, the thermal transfer and the capillary effect of the growing interface has been derived. The well known scaling law λ²V = const can be derived from this relation. Directional solidification of regular Al-Al₂Cu eutectic and irregular Al-Si eutectic has been investigated experimentally, the coupling relation has been verified. The solidifying interface profile and thermal transfer effect of solidification have also been discussed.