Computational and Experimental Characterization of Twin-twin Interactions in Hexagonal Metals

六方金属中孪晶相互作用的计算和实验表征

• 批准号: 1661686
• 负责人: Jian Wang
• 金额: $ 38.8万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1661686&HistoricalAwards=false
• 关键词: Computational; Experimental; Characterization; Twin; twin

Hexagonal metals, such as magnesium and titanium with hexagonal close packed structure, have the potential for increasing the efficiency of fuel consumption because of their superior strength-to-density ratio. In particular, magnesium with a density low enough to make it 35 percent lighter than aluminum and 78 percent lighter than steel is perhaps the most appealing of these lightweight materials. Replacing steel structural materials with magnesium-based materials in automotive applications would boost fuel efficiency by more than 50 percent. However, magnesium's use remains fairly limited because of a gap in the knowledge of a phenomenon called twin-twin interactions. Twins are specific features in hexagonal materials that can occur from the nanoscale to microscale and responsible for what is called deformation twinning, which is a major mode of plasticity in magnesium and responsible for its low strength and poor deformability. This research will focus on understanding the effect of twin-twin interactions on the mechanisms of deformation in magnesium by performing modeling at multiple scales supported by experimental observations. The outcome will be a predictive model that would allow engineers and scientists to optimize the processing routes of hexagonal metals for specific structural and environmental applications. As part of this research, students will be provided an opportunity to be trained at a national laboratory. Undergraduate students from underrepresented groups will be hired as part of the research team, and K-12 students will be exposed to the research through outreach events.The long-term goal of this research is to establish a research framework for quantitatively characterizing and predicting the twinning induced microstructures and mechanical properties of hexagonal materials. It will link the macroscopic plastic responses to the crystallographic mechanisms causing them, while also accounting for microstructure evolution. To do so, the research team will characterize microstructures of twin-twin boundaries at the atomic level through atomistic simulations and transmission electron microscopes; identify twin-twin boundaries dominated deformation mechanisms at the atomic-/micro-scales by using atomistic simulations and in situ nanomechanical testing in scanning electron microscopies; establish twin-twin interaction models at the meso-scale by combining in situ mechanical testing and finite element analysis, and implement the meso-scale models into macro-scale effective-medium polycrystal plasticity models. The numerical and experimental tools developed through this project will eventually enable design of manufacturing processes for specific structural and environmental applications.

六角形金属，例如具有六角形封闭结构的镁和钛，由于其优势强度密度比，具有提高燃油消耗效率的潜力。特别是，密度低的镁比铝轻35％，比钢轻78％是这些轻质材料中最具吸引力的镁。在汽车应用中，用镁基材料代替钢结构材料将提高燃油效率超过50％。但是，由于知道一种称为双敌人相互作用的现象的差距，镁的使用仍然相当有限。双胞胎是六角形材料的特定特征，可以从纳米级到显微镜出现，并对所谓的变形双胞胎负责，这是镁的可塑性的主要方式，并且负责其低强度和差的可变形性。这项研究将着重于理解双线相互作用对镁变形机制的影响，通过在实验观察支持的多个尺度上进行建模。结果将是一个预测模型，该模型将使工程师和科学家能够为特定的结构和环境应用优化六边形金属的处理途径。作为这项研究的一部分，将为学生提供在国家实验室接受培训的机会。来自代表性不足的小组的本科生将被聘为研究团队的一部分，K-12学生将通过外展事件接触研究。这项研究的长期目标是建立一个研究框架，以定量表征和预测双胞胎诱导的微观结构和机械性能。它将将宏观塑料反应与导致它们的晶体学机制联系起来，同时还考虑了微观结构的演变。为此，研究团队将通过原子模拟和传输电子显微镜来表征原子水平上双键边界的微观结构。通过使用原子模拟和扫描电子显微镜中的原子纳米力学测试来确定在原子 - /微尺度上占主导的变形机制；通过结合原位机械测试和有限元分析，并将中尺度模型实施到宏观尺度有效的多晶可塑性模型中，并将中尺度模型实现在中尺度上，建立双键相互作用模型。通过该项目开发的数值和实验工具最终将为特定的结构和环境应用设计制造过程。

项目成果

Crystallographic characters of {11¯22} twin-twin junctions in titanium

• DOI: 10.1080/09500839.2017.1402132
• 发表时间: 2017-11
• 期刊: Philosophical Magazine Letters
• 影响因子: 1.2
• 作者: Shun Xu;M. Gong;Xinyan Xie;Yue Liu;C. Schuman;J. Lecomte;Jian Wang

Extension of the classical theory for types I and II twinning

• DOI: 10.1557/s43578-020-00003-6
• 发表时间: 2021-01-05
• 期刊: JOURNAL OF MATERIALS RESEARCH
• 影响因子: 2.7
• 作者: Hirth, J. P.;Wang, J.
• 通讯作者: Wang, J.

A topological model for defects and interfaces in complex crystal structures

• DOI: 10.2138/am-2019-6892
• 发表时间: 2019-07-01
• 期刊: AMERICAN MINERALOGIST
• 影响因子: 3.1
• 作者: Hirth, J. P.;Wang, Jian;Hirth, Greg
• 通讯作者: Hirth, Greg

Experimentally quantifying critical stresses associated with basal slip and twinning in magnesium using micropillars

• DOI: 10.1016/j.actamat.2017.06.008
• 发表时间: 2017-08-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Liu, Y.;Li, N.;Tome, C. N.
• 通讯作者: Tome, C. N.

Pre-compression effect on microstructure evolution of extruded pure polycrystalline magnesium during reversed tension load

• DOI: 10.1016/j.matchar.2017.10.003
• 发表时间: 2017-12
• 期刊: Materials Characterization
• 影响因子: 4.7
• 作者: D. Culbertson;Qin Yu;Jian Wang;Yanyao Jiang