| 初始微观结构缺陷和断裂的温度依赖及相关性 | |
| Temperature dependence and correlation of initial microstructural defects and breaking | |
| 摘要: 纳米线(NW)结构内的微观结构缺陷对NW的机械性能存在一定的影响。NW断裂位置的预测关系着纳米器件应用的寿命,进而引起了人们的广泛关注。在本工作中,基于统计分析,分别研究了单晶铜纳米线(Cu NW)拉伸过程中出现的断裂位置以及在应力屈服点处产生的初始微观结构缺陷(初始缺陷)的位置对温度的依赖性,进一步探究了两者之间的联系。利用分子动力学(MD)模拟了单晶Cu NW在20~300 K的温度范围内的拉伸状态,共包含6个体系,各温度体系包含300个独立的样本。基于机器学习,采用density-based spatial clustering of applications with noise (DBSCAN)算法,将hexagonal close-packed (hcp)原子划分为各个初始缺陷以进一步确定其位置。统计结果显示,当温度低于50 K时,初始缺陷的位置集中在NW的两端。随着模拟温度的上升,MD模拟结果展现了单晶Cu NW的拉伸过程中的杨氏模量、平均屈服应力、平均势能等机械性能对温度的依赖性。温度的升高进一步促使了更多初始缺陷的产生,并使得初始缺陷的位置由统计分布的两端向中间平均化。与初始缺陷相比,各温度下的断裂位置集中在两端。统计结果表明,模拟的温度范围对NW的断裂位置无明显影响,但对初始缺陷的产生具有明显影响。当温度低于100 K时,初始缺陷的位置分布与断裂位置分布呈现了一致性。由于两者具有不同的温度依赖,其差异随着温度的上升逐渐显现。对不同温度下的微观结构形变行为观察发现,断裂失效明显受到NW两端的表面效应和阻挡效应的影响。最终的断裂位置受塑性形变中后期的影响,与应力屈服区产生的初始缺陷无直接联系。 | |
| 关键词: 纳米线 初始微观结构缺陷 断裂失效 分子动力学 统计分析 机械性能 | |
| 基金项目: 国家自然科学基金国际(地区)合作与交流(No.51861145202)资助。 | |
| Abstract: The microstructural defects within the nanowire (NW) have a significant impact on the mechanical properties of the NW. The prediction of the breaking position of the NW has raised concerns owning to it is a crucial point in the application of nanodevices. In this work, based on the statistical analysis, the breaking positions and the positions of the initial microstructural defects generated at the stress yield point are studied separately to analyze their temperature dependence, then further investigate the relationship between the breaking failure and the initial microstructural defects. At the temperature range from 20 to 300 K, including six ensembles, the single-crystal Cu NWs have been performed using molecular dynamics (MD) simulations. The ensemble at each temperature includes 300 independent samples. Based on machine learning, the hexagonal close-packed (hcp) atoms at the stress yield point have been clustered to every initial microstructural defect by the density-based spatial clustering of applications with noise (DBSCAN) algorithm. According to the statistical results, it is found that the initial microstructural defects of NWs simulated in this paper tend to generate at the two ends of the NW while the temperature is less than 50 K. Following the increasing temperature, the MD simulation results have shown a strong temperature dependence of mechanical properties for the single-crystal Cu NWs, including Young's modulus, average yield stress, average potential energy, etc. It is attributed that there are more initial microstructural defects generated as the increase in temperature, and the positions of initial microstructural defects are averaged out from the two ends of the distribution towards the middle part. The breaking positions for all the simulation temperatures are mainly concentrated on the ends of the NW. The statistical results indicate that this temperature range has little effect on breaking position but a great effect on the initial microstructural defects. It shows a consistency between the initial slip distributions and breaking distributions while the temperature is less than 100 K. However, it has been observed that the differences between them are gradually shown with the increase in temperature due to their different temperature dependents. The microstructural deformation behaviors under different temperatures reveal that the breaking failure is affected by the surface effect and blocking effect of the ends. Based on the results, the final breaking position is correlated to the middle and late stages of the plastic deformation rather than the positions of initial microstructural defects first generated. | |
| Keywords: nanowires initial microstructural defects breaking failure molecular dynamics statistical analysis mechanical properties | |
| 投稿时间：2022-12-01 修订日期：2023-04-21 | |
| 摘要点击次数: 710 | |
| 全文下载次数: 240 | |
| 赵健伟,沈坤燕,于晓辉,侯进.初始微观结构缺陷和断裂的温度依赖及相关性[J].无机化学学报,2023,39(6):1193-1207. | |
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| Support information: 相关附件： 220524_Supplemental_files (2).doc | |
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