Atomistic study of crack-tip cleavage to dislocation emission transition in silicon single crystals.
Atomistic study of crack-tip cleavage to dislocation emission transition in silicon single crystals.
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DOI：
10.1103/physrevlett.104.235502
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发表时间：
2010-06
影响因子：
8.6
通讯作者：
Dipanjan Sen;C. Thaulow;S. Schieffer;Alan Cohen;M. Buehler
中科院分区：
文献类型：
--
作者：
Dipanjan Sen;C. Thaulow;S. Schieffer;Alan Cohen;M. Buehler
在低温下，硅是一种脆性材料，会灾难性地破碎，而在高温下，硅的行为在很窄的温度范围内急剧变化，突然变得具有延展性。在实验研究中已经观察到这种脆韧性转变，但其基本机制仍然未知。在这里，我们报告了一个原子级的研究在这个过渡的基本事件，从脆性解理断裂的变化，位错发射在裂纹尖端，使用第一原理为基础的反应力场。通过单独提高温度，我们观察到一个突然的变化，从脆性开裂的位错发射从一个裂纹内的一个10K的温度区间。
At low temperatures silicon is a brittle material that shatters catastrophically, whereas at elevated temperatures, the behavior of silicon changes drastically over a narrow temperature range and suddenly becomes ductile. This brittle-to-ductile transition has been observed in experimental studies, yet its fundamental mechanisms remain unknown. Here we report an atomistic-level study of a fundamental event in this transition, the change from brittle cleavage fracture to dislocation emission at crack tips, using the first principles based reactive force field. By solely raising the temperature, we observe an abrupt change from brittle cracking to dislocation emission from a crack within a ≈10 K temperature interval.