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纳米晶的纹理:探测脱位活动的下面尺寸极限
Bin Chen1, Katie Lutker, Selva Vennila Raju
1Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA. bchen@lbl.gov
Science (New York, N.Y.)
|December 15, 2012
概括
纳米晶体中的塑料变形受到尺寸的限制. 然而,实验表明,即使在极端压力下,3纳米晶体中,脱位活动仍然存在,从而扩展了纳米尺度变形能力.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
- 固体力学 固体力学是什么
背景情况:
- 纳米晶体大小通常限制了脱位活动和塑性变形.
- 预测的关键颗粒大小 (10-30纳米) 是由于脱位介导的塑性变形的不活性.
- 之前的研究依赖于模拟和传输电子显微镜 (TEM) 来确定这个关键尺寸.
研究的目的:
- 在高压条件下研究纳米晶中的脱位活动和塑性变形.
- 为了确定在极小的纳米晶体 (3纳米) 中在高压下是否存在脱位活动.
- 为了检查压力对不同尺寸的纳米晶纹理的影响.
主要方法:
- 在不同尺寸 (500nm,20nm和3nm) 的多晶样本上进行高压变形实验.
- 作为施加压力和纳米晶体大小的函数,分析纹理演变的分析.
- 使用能够进行高压材料分析的技术.
主要成果:
- 观察到,与预测相反,在3纳米晶体中,脱位活动是可操作的.
- 在 500 nm 中,在 >3.0 GPa 和在 20 nm 中,在 >11.0 GPa 中,引起了显著的纹理.
- 令人惊的是,在压缩在18.5GPa以上时,在3nm中也观察到纹理.
结论:
- 高的外部压力可以将脱位活动延伸到几纳米的长度尺度.
- 失位不活性的关键粒子大小可能比先前估计的小,特别是在压力下.
- 压力促成的纹理为超小纳米晶体中持续的脱位活动提供了证据.
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