Si和SiC纳米粒子的超高强度和可塑性机制由第一原理分子动力学揭示
1Institut Pprime, CNRS UPR 3346, Université de Poitiers, SP2MI, Boulevard Marie et Pierre Curie, TSA 41123, 86073 Poitiers Cedex 9, France.
Physical review letters
|December 22, 2023
概括
和碳化 (SiC) 的纳米粒子在纳米尺度上表现出强度的增加. 它们的机械性能,包括强度和可塑性,使用先进的模拟来研究,揭示了这些小尺寸的独特行为.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
- 计算物理 计算物理
背景情况:
- 材料表现出增强的强度,因为尺寸减少到亚微米尺度.
- 材料在几纳米尺度上的机械性能和变形机制仍然不太清楚,结果相互矛盾.
- 研究纳米级材料对于开发先进技术至关重要.
研究的目的:
- 在压缩下研究1-2纳米 (Si) 和碳化 (SiC) 纳米粒子的机械性能.
- 确定这些纳米粒子在几纳米尺度上的强度极限和变形机制.
- 为了比较Si和SiC纳米粒子的行为,并识别独特的纳米尺度现象.
主要方法:
- 利用了第一原则的分子动力学 (MD) 模拟.
- 在MD模拟中使用经典的力场.
- 在1-2nmSi和SiC纳米粒子上进行了压缩测试.
主要成果:
- 随着尺寸缩小到1-2nm,纳米粒子强度继续增加,达到或超过理论散装强度.
- 收益率主要通过在20%以上的应变时的无形化发生,Si纳米粒子中没有观察到β-相.
- 鉴定出了独特的变形机制,包括SiC中均的脱位环胚胎形成和Si纳米颗粒的弹性软化.
结论:
- 强度增强趋势持续到Si和SiC纳米粒子的几纳米级.
- 形态化是这些小尺度上占主导地位的产生机制,与散装材料的行为不同.
- 纳米级的新型变形机制为材料行为和潜在应用提供了新的见解.
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