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.

六方金属，例如具有六方密堆积结构的镁和钛，由于其优异的强度密度比而具有提高燃料消耗效率的潜力。特别是，镁的密度足够低，比铝轻 35%，比钢轻 78%，可能是这些轻质材料中最具吸引力的。在汽车应用中用镁基材料替代钢结构材料可将燃油效率提高 50% 以上。然而，由于对孪生相互作用现象的了解存在差距，镁的使用仍然相当有限。孪晶是六方材料中的特定特征，可以从纳米尺度到微米尺度发生，并导致所谓的变形孪晶，这是镁塑性的主要模式，导致其强度低和变形能力差。这项研究将重点通过在实验观察支持的多个尺度上进行建模来了解孪晶相互作用对镁变形机制的影响。其结果将是一个预测模型，使工程师和科学家能够针对特定的结构和环境应用优化六方金属的加工路线。作为这项研究的一部分，学生将有机会在国家实验室接受培训。来自代表性不足群体的本科生将被聘为研究团队的一部分，K-12 学生将通过外展活动接触到这项研究。这项研究的长期目标是建立一个研究框架，用于定量描述和预测六方材料的孪晶诱导微观结构和力学性能。它将宏观塑性反应与引起它们的晶体学机制联系起来，同时也解释了微观结构的演变。为此，研究小组将通过原子模拟和透射电子显微镜在原子水平上表征孪晶边界的微观结构；通过使用原子模拟和扫描电子显微镜中的原位纳米力学测试，确定原子/微观尺度上孪晶边界主导的变形机制；通过原位力学测试和有限元分析相结合，建立细观尺度的孪生相互作用模型，并将细观模型转化为宏观尺度有效-介质多晶塑性模型。通过该项目开发的数值和实验工具最终将实现针对特定结构和环境应用的制造工艺设计。

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

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

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.