The formation of multiple parallel twin boundaries at grain boundary grooves during Si solidification was investigated using an in situ observation system. Twin boundaries were repeatedly generated at a crystal/melt interface from a step-like grain boundary during solidification. The growth velocity of the micro-facet at the grain boundary groove accelerated and decelerated, which resulted in the nucleation of a twin and the development of a step-like structure at the grain boundary. The undercooling for multiple parallel twin formation as estimated based on experimental observation and the result was further discussed by comparison with previous studies.

中文翻译：

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硅凝固过程中由阶梯状晶界形成的多个平行（1 1 1）孪晶边界的原位观察

利用原位观察系统研究了硅凝固过程中晶界槽处多个平行孪晶边界的形成。在凝固过程中，从阶梯状晶界在晶/熔体界面处反复产生孪晶界。微晶面在晶界槽处的生长速度加速和减速，从而导致孪晶形核并在晶界处形成阶梯状结构。根据实验观察估计的多个平行孪晶形成的过冷度与结果进行了比较，并与以前的研究进行了进一步讨论。