Pre-nucleation clusters mediated crystallization in Al-Si melts

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• 作者：Yue Liu¹ ; Yong Zhang¹ ; Wenhui Yu ; Xuetao Wang ; Hongliang Zheng ; Xuelei Tian ; ^{tianxuelei@sdu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Pre-nucleation clusters ; Aluminum alloys ; Solidification ; Nucleation ; Grain growth
• 刊名：Scripta Materialia
• 出版年：2016
• 出版时间：1 January 2016
• 年：2016
• 卷：110
• 期：Complete
• 页码：87-91
• 全文大小：1914 K

文摘

Triggered by exogenous local ordering structures, pre-nucleation clusters appear in Al–Si melts and significantly alter the crystallization process. In absence of potent nucleating substrates (in high-purity melts), they delay silicon crystal nucleation, otherwise (in commercial-purity melts), they enhance nucleation and growth as well as change the growth mechanism of silicon. This makes the silicon grain size a competition result of nucleation and growth processes and some empirical rules of classical nucleation unreliable, e.g., easy nucleation no longer means grain-refined microstructures. These phenomena are further explained by characterizing the remains of these pre-nucleation clusters in solidified alloys.