Collaborative Research: Brittle-to-Ductile Transition and Strength of Silicon Nanowires at Elevated Temperatures

合作研究：高温下硅纳米线的脆性转变和强度

• 批准号: 1762463
• 负责人: Ting Zhu
• 金额: $ 27.45万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1762463&HistoricalAwards=false
• 关键词: Collaborative; Research; Brittle; Ductile; Transition

Silicon is the most commonly used material in the modern electronic and micro/nano electro-mechanical systems. Brittle fracture is a serious roadblock to the development of reliable silicon nanostructures for practical use in micro/nano devices. Initial evidence suggests that at elevated temperatures, brittle to ductile behavior transition is possible in silicon nanowires, which presents hope for more reliable applications. This research will advance the fundamental understanding of the deformation mechanisms underlying such transition at elevated temperatures. The findings will provide the mechanical basis for the design of strong and ductile silicon nanostructures at elevated temperatures, thus advancing national health, prosperity, and welfare. In addition, the project will promote the progress of nanoengineering by developing novel experimental and modeling methods for nanoscale research at elevated temperatures. For broader impact, appropriate lessons from research will be integrated into a course module for an Atlanta high school with a large minority student body as well as in an undergraduate course at North Carolina State University. Moreover, undergraduate students will be recruited to perform advanced research.There is currently a critical lack of fundamental knowledge and understanding of the thermomechanical behavior of nanoscale silicon (Si) at elevated temperatures. The objective of this project is to quantify the temperature, strain rate, and sample size effects on the strength and brittle-to-ductile transition (BDT) in Si nanowires, with the help of novel in-situ thermomechanical experimentation in transmission electron microscopy (TEM) and atomistic modeling. To understand BDT and associated strength-controlling deformation mechanisms, the research involves three tightly coupled thrusts: (i) to measure and calculate the yield/fracture strengths of Si nanowires at different temperatures, strain rates and sample sizes and analyze the data based on the Weibull statistics; (ii) to obtain activation parameters (including activation energy and activation volume) of Si nanowires as functions of temperature, strain rate, sample size, surface and internal structures, and to perform in-situ TEM characterization of dislocation and fracture mechanisms; (iii) to conduct the molecular dynamics and atomistic reaction pathway modeling to elucidate the rate-limiting dislocation mechanisms that control the strength and BDT by coupling modeling results with in-situ measurements and TEM characterization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

硅是现代电子和微/纳米电力机械系统中最常用的材料。脆性断裂是开发可靠的硅纳米结构的严重障碍，用于在微/纳米设备中实际使用。最初的证据表明，在较高的温度下，硅纳米线可能是可能的延性到延性行为过渡，这为更可靠的应用带来了希望。这项研究将提高对高温下过渡的变形机制的基本理解。这些发现将为在升高温度下设计强和延性硅纳米结构的设计提供机械基础，从而促进了民族健康，繁荣和福利。此外，该项目将通过在温度升高时开发新的实验和建模方法来促进纳米工程的进步。为了获得更广泛的影响，研究的适当课程将纳入亚特兰大高中的课程模块，该模块具有少数族裔学生团体以及北卡罗来纳州立大学的本科课程。此外，本科生将被招募来进行高级研究。目前，在升高温度下，迫切缺乏对纳米级硅（SI）的热机械行为的基本知识和理解。该项目的目的是借助新型的位于透射式电子显微镜（TEM）和原子模型的透射热力学实验的SI纳米线的强度和脆性转变（BDT）的温度，应变速率和样本量影响。为了了解BDT和相关的强度控制变形机制，该研究涉及三个紧密耦合的推力：（i）在不同温度，应变率和样本尺寸和样本大小和样本大小和基于Weibull统计数据下测量和计算SI纳米线的产量/断裂强度； （ii）获得SI纳米线的激活参数（包括活化能和激活量）作为温度，应变速率，样本量，表面和内部结构的功能，并执行位错和断裂机制的原位特征； (iii) to conduct the molecular dynamics and atomistic reaction pathway modeling to elucidate the rate-limiting dislocation mechanisms that control the strength and BDT by coupling modeling results with in-situ measurements and TEM characterization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

项目成果

In Situ Nano-thermomechanical Experiment Reveals Brittle to Ductile Transition in Silicon Nanowires

• DOI: 10.1021/acs.nanolett.9b01789
• 发表时间: 2019-08-01
• 期刊: NANO LETTERS
• 影响因子: 10.8
• 作者: Cheng, Guangming;Zhang, Yin;Zhu, Yong
• 通讯作者: Zhu, Yong