在纳米晶体铜的强度的最大值
Jakob Schiøtz1, Karsten W Jacobsen
1Center for Atomic-Scale Materials Physics (CAMP), Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark. schiotz@fysik.dtu.dk
概括
铜中的塑料变形在10-15nm颗粒大小时显示出最大的强度. 这是由于谷物尺寸随着谷物尺寸的减少而从脱位转变为谷物边界滑动机制.
科学领域:
- 材料科学 材料科学 材料科学
- 计算材料科学科学 计算材料科学
- 纳米技术纳米技术
背景情况:
- 纳米晶体材料的机械性能高度依赖于它们的微观结构特征.
- 了解颗粒大小和材料强度之间的关系对于设计先进材料至关重要.
研究的目的:
- 用大规模模拟研究纳米晶铜中的塑性变形机制.
- 为了确定颗粒大小对纳米晶体铜的强度和流应力的影响.
- 阐明对观察到的颗粒大小增强或减弱效应负责的潜在显微机制.
主要方法:
- 采用了高达1亿个原子的系统大小的分子动力学模拟.
- 纳米晶体铜样本的颗粒大小在5至50纳米之间变化.
- 分析了变形机制的变化作为颗粒大小的函数.
主要成果:
- 在10至15纳米的颗粒大小下,确定了流应力和材料强度的峰值.
- 观察到占主导地位的塑性变形机制的转变.
- 脱位介导的可塑性在较粗的粒度中普遍存在,而在纳米晶体区域中则以粒度边界滑动为主.
结论:
- 纳米晶体铜的强度在特定的颗粒大小范围 (10-15纳米) 上表现为最大.
- 这种最大强度归因于变形机制的根本转变.
- 模拟结果提供了对多晶金属机械性质的颗粒大小依赖性的见解.
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