Visualization of morphological instability and development in directional solidification of an alloy

• Main Authors: Wei Tse Shu, 徐為哲
• Other Authors: ChungWenLan
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/34028435118217260110

碩士 === 國立臺灣大學 === 化學工程學研究所 === 91 === Abstract During directional solidification of an alloy, the control of interface morphology is very important to the quality of crystals. Generally speaking, the planar interface is preferable in the crystal growth and the floating zone purification, and the dendritic structure is often used to alloy casting. There are so many people pay much attention to this project and many papers were presented. However, there are fewer researches about the long-time scale experiment. Based on this reason, we set up a visual directional solidification system for the long-time scale observation, and the ultra pure SCN is also prepared in the laboratory. Thus, we can see the evolution of the solid-melt interface during solidification after the doping of acetone. At high doping concentration and low velocity, it was found that cellular structures propagate over the entire interface and the shallow cells wavelength distribution is wider comparing with the ones at low doping concentration after long time observation. Moreover, we did not observe the regular deep cell at low doping concentration and high velocity. According to these results, we can summarize that the doping concentration effect on the interface morphology is very critical.