快速凝固中枝晶形态原位观察

In-situ Observation of Dendrite Morphology in Rapid Solidification

提出了一种适于原位观察的晶体生长试验装置,主要包括“三明治”型晶体生长室和恒温水循环控制系统,及一种基于流动显示技术的新型光路。通过对高纯丁二腈(SCN)模拟合金在不同温度梯度下快速凝固的原位观察,展示了枝晶形态的转变过程,发现枝晶通过尖端开裂使侧枝消失并伴随一次间距大幅减小;对尖端开裂的演化机制进行了理论分析。

An in-situ observation instrument for crystal growth was developed, which was composed of a sandwich-like crystal growth cell, circulation system of hot water and a light path based on flowing visualization method designed to match the crystal growth cell. The morphological transformation from dendrite to cells has been demonstrated by in-situ observing the growth process of SCN analogue alloy in rapid solidification with different temperature gradients. It is found that the tip splitting of the dendrite can result in the coalesce of side-dendrite and the sharp decrease of first arm spacing. The theoretical approach to evolving mechanism of the tip splitting is conducted also.