Collaborative Research: EAGER: Interactions Between Dislocations and Grain Boundaries in BCC Metals: Hall-Petch Effect

合作研究：EAGER：BCC 金属中位错和晶界之间的相互作用：霍尔佩奇效应

• 批准号: 0936340
• 负责人: Robert Wagoner
• 金额: $ 15.55万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0936340&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Interactions; Between

Technical Summary:A numerically tractable multi-scale model incorporating the effects of large numbers of discrete dislocations will be constructed and compared with novel electron-backscattering diffraction (EBSD)-based characterization to address the long-standing open question: ?Why does the mechanical strength of polycrystalline metals vary with grain size (Hall-Petch Effect)?? The model will avoid arbitrary length scales (strain gradients) and unobserved microstructures (linear pile-ups). Instead, a predictive capability will be constructed and tested. The new modeling and characterization capabilities will enable material design and improve applications, e.g. metal forming, particular for body-centered cubic metals such as steels. The advances will be incorporated in instructional modules at the two participating universities; undergraduate and graduate students will be trained in research practices; EBSD sensitivity will be extended by up to two orders of magnitude; and results will be disseminated widely by peer-reviewed publications, theses, and dissertations.Non-Technical Summary:The strength of common structural metals (e.g. steel, copper, aluminum, titanium) varies greatly with the scale of its microstructures. For example, the strength of steel can be increased 10 times by changing the grain size alone. There is no confirmed mechanism or model that predicts this well-known effect quantitatively. In order to facilitate the design and use of better, stronger materials, a predictive multi-scale (micro/macro) model will be constructed and tested using new analytical techniques. Benefits of a fundamental understanding of this important effect will permit production and use of better materials, resulting in a variety of societal advantages such as increased personal and national safety, reduced fuel consumption, and reduction of greenhouse gas emissions.

技术摘要：将构建一个包含大量离散位错效应的数值可处理的多尺度模型，并将其与基于新型电子背散射衍射 (EBSD) 的表征进行比较，以解决长期悬而未决的问题：“为什么多晶金属的机械强度随晶粒尺寸变化（霍尔-佩奇效应）？”该模型将避免任意长度尺度（应变梯度）和未观察到的微观结构（线性堆积）。相反，将构建并测试预测能力。新的建模和表征功能将支持材料设计并改进应用，例如金属成型，特别是体心立方金属，例如钢。 这些进展将被纳入两所参与大学的教学模块中；本科生和研究生将接受研究实践培训； EBSD 灵敏度将提高两个数量级；结果将通过同行评审的出版物、论文和学位论文广泛传播。非技术摘要：常见结构金属（例如钢、铜、铝、钛）的强度随其微观结构的规模变化很大。例如，仅改变晶粒尺寸即可将钢的强度提高10倍。没有已证实的机制或模型可以定量预测这种众所周知的效应。为了促进更好、更强材料的设计和使用，将使用新的分析技术构建和测试预测性多尺度（微观/宏观）模型。 从根本上了解这一重要效应将有助于生产和使用更好的材料，从而带来各种社会优势，例如提高个人和国家安全、减少燃料消耗以及减少温室气体排放。