COLLABORATIVE RESEARCH: NANOMESO: A NSF-EC Cooperative Activity in Computational Research to Study Nano/Meso Length Scale Effects on Crystal Plasticity

技术说明 该合作奖项是针对提交给 2005 财年 NSF-EC 计算材料研究合作活动的提案而颁发的。 该项目涉及美国俄亥俄州立大学、斯坦福大学和洛斯阿拉莫斯国家实验室以及瑞士、德国和荷兰的合作机构。 这项合作活动的目的是开发和验证一种计算方法，以理解和预测纳米和亚微米尺度的独特塑性现象。 近年来，合成、表征和计算技术的进步相结合，揭示了传统晶体塑性理论甚至更新的应变梯度理论无法解释的惊人塑性现象。 这些现象与将样品尺寸缩小到亚微米范围以及将结构长度尺度（例如晶粒尺寸）减小到纳米尺度范围有关。 一个令人兴奋的前景是，已经确定了新的变形机制，如果能够理解这些机制，就可以开发出具有无与伦比强度的材料。 因此，所提出的工作的主要影响是理解当前塑性理论未解决的长度尺度上的材料强度。 这样的活动预计将影响我们对薄膜强度和加工硬化的理解，并指导我们对 MEMS 中使用的小型设备的适当材料参数的理解。该项目的高智力价值源于解决亚微米和纳米级样品所造成的可塑性基本性质的目标，以及使用计算材料科学的从头算、原子论和 Peierls 方法来支持位错动力学水平建模与新型微柱和原位X射线衍射验证技术。 当前塑性理论（包括应变梯度公式）的不足之处将通过系统方法得到解决，其中将系统地研究交叉滑移动力学以及自由表面和晶界作为源和汇的作用。 这项研究的一个令人兴奋的前提是，亚微米和纳米级样品可能从“位错饥饿”中获得非凡的强度。 主要成果是，所提出的几种计算技术之间的集中相互作用将为亚微米和纳米级部件的新可塑性理论提供基础。该项目的更广泛影响源于当前工业和科学对了解小型设备特性的推动力。 该研究旨在通过提供计算工具库来实现小型机械设备的设计和开发，通过该工具库来预测随着尺寸和结构缩小到亚微米和纳米级的部件的机械性能。 我们的计算和实验结果将被打包到一个开放的网站中，供学术界和工业界使用，特别是美国和欧盟的学术界和工业界，并将为亚微米尺度的全面、可访问的计算材料结果开创先例。致力于代表性不足群体参与的研究人员、国际合作提供的独特教育交流以及拟议的一系列基于网络的讲座，以教授本研究中使用的每种计算材料方法的基础，从而增强教育影响。非技术解释该合作奖项是为了响应提交给 2005 财年 NSF-EC 计算材料研究合作活动的提案而颁发的。 该项目涉及美国俄亥俄州立大学、斯坦福大学和洛斯阿拉莫斯国家实验室以及瑞士、德国和荷兰的合作机构。 这项合作活动的目的是开发和验证一种计算方法，以理解和预测纳米和亚微米尺度的独特塑性现象。 近年来，合成、表征和计算技术的进步相结合，揭示了传统晶体塑性理论甚至更新的应变梯度理论无法解释的惊人塑性现象。 这些现象与将样品尺寸缩小到亚微米范围以及将结构长度尺度（例如晶粒尺寸）减小到纳米尺度范围有关。 一个令人兴奋的前景是，已经确定了新的变形机制，如果能够理解这些机制，就可以开发出具有无与伦比强度的材料。 因此，所提出的工作的主要影响是理解当前塑性理论未解决的长度尺度上的材料强度。 这样的活动预计将影响我们对薄膜强度和加工硬化的理解，并指导我们对 MEMS 中使用的小型设备的适当材料参数的理解。该项目的高智力价值源于解决亚微米和纳米级样品所造成的可塑性基本性质的目标，以及使用计算材料科学的从头算、原子论和 Peierls 方法来支持位错动力学水平建模与新型微柱和原位X射线衍射验证技术。 当前塑性理论（包括应变梯度公式）的不足之处将通过系统方法得到解决，其中将系统地研究交叉滑移动力学以及自由表面和晶界作为源和汇的作用。 这项研究的一个令人兴奋的前提是，亚微米和纳米级样品可能从“位错饥饿”中获得非凡的强度。 主要成果是，所提出的几种计算技术之间的集中相互作用将为亚微米和纳米级部件的新可塑性理论提供基础。该项目的更广泛影响源于当前工业和科学对了解小型设备特性的推动力。 该研究旨在通过提供计算工具库来实现小型机械设备的设计和开发，通过该工具库来预测随着尺寸和结构缩小到亚微米和纳米级的部件的机械性能。 我们的计算和实验结果将被打包到一个开放的网站中，供学术界和工业界（特别是美国和欧盟的学术界和工业界）使用，并将为亚微米尺度上全面、可访问的计算材料结果开创先例。致力于代表性不足群体参与的研究人员、国际合作提供的独特教育交流以及拟议的一系列基于网络的讲座来教授该计划中使用的每种计算材料方法的基础，将增强教育影响。

TECHNICAL EXPLANATION This collaborative award is made in response to proposals submitted to the FY05 NSF-EC Cooperative Activity in Computational Materials Research. The project involves the Ohio State University, Stanford University and Los Alamos National Laboratory in the US and collaborating institutions in Switzerland, Germany and the Netherlands. The aim of this cooperative activity is to develop and validate a computational approach to understand and predict unique plasticity phenomena at the nano and sub-micron scales. In recent years, a combination of advances in synthesis, characterization, and computational techniques has revealed striking plasticity phenomena that are not explained by traditional crystal plasticity theories or even more recent strain gradient theories. These phenomena are associated with shrinking sample size to the sub-micron regime and decreasing structural length scales such as grain size to the nano-scale regime. An exciting prospect is that new deformation regimes have been identified which, if understood, could enable the development of materials with unrivaled strength. Thus, the primary impact of the proposed work is an understanding of material strength at length scales not addressed by current plasticity theories. Such an activity is expected to impact our understanding of strength and work hardening in thin films and guide our understanding of appropriate material parameters for small-scale devices used in MEMS.The high intellectual merit of this project derives from a goal to address the fundamental nature of plasticity posed by sub-micron and nano-scale samples, and from the creative process by which ab initio, atomistic, and Peierls approaches to computational materials science are used to support a direct comparison between dislocation dynamics level modeling and novel micro-pillar and in-situ x-ray diffraction verification techniques. The inadequacies of current plasticity theories, including strain gradient formulations, will be addressed via a systematic approach in which the kinetics of cross slip and role of free surfaces and grain boundaries as sources and sinks will be systematically studied. An exciting premise in this investigation is that sub-micron and nano-scale samples may derive extraordinary strength from "dislocation-starvation." A principle outcome is that the proposed, focused interaction among several computational techniques will provide the basis for a new plasticity theory for sub-micron and nano-scale components.The broader impact of the project draws from the current industrial and scientific thrusts to understand the properties of small devices. The research is aimed at enabling small mechanical device design and development, by providing a computational tool base with which to predict the mechanical properties of components as size and structure are diminished to the sub-micron and nano-scale. Our computational and experimental findings will be packaged into an open web site for use by the academic and industrial communities - particularly those in the US and EC - and will set a precedent for comprehensive, accessible computational materials results at the sub-micron scale.The educational impact will be enhanced by investigators who are commited to participation from under-represented groups, the unique educational exchange offered by an international collaboration, and a proposed series of web-based lectures to teach the basis of each of the computational materials methods to be used in this program.NON-TECHNICAL EXPLANATIONThis collaborative award is made in response to proposals submitted to the FY05 NSF-EC Cooperative Activity in Computational Materials Research. The project involves the Ohio State University, Stanford University and Los Alamos National Laboratory in the US and collaborating institutions in Switzerland, Germany and the Netherlands. The aim of this cooperative activity is to develop and validate a computational approach to understand and predict unique plasticity phenomena at the nano and sub-micron scales. In recent years, a combination of advances in synthesis, characterization, and computational techniques has revealed striking plasticity phenomena that are not explained by traditional crystal plasticity theories or even more recent strain gradient theories. These phenomena are associated with shrinking sample size to the sub-micron regime and decreasing structural length scales such as grain size to the nano-scale regime. An exciting prospect is that new deformation regimes have been identified which, if understood, could enable the development of materials with unrivaled strength. Thus, the primary impact of the proposed work is an understanding of material strength at length scales not addressed by current plasticity theories. Such an activity is expected to impact our understanding of strength and work hardening in thin films and guide our understanding of appropriate material parameters for small-scale devices used in MEMS.The high intellectual merit of this project derives from a goal to address the fundamental nature of plasticity posed by sub-micron and nano-scale samples, and from the creative process by which ab initio, atomistic, and Peierls approaches to computational materials science are used to support a direct comparison between dislocation dynamics level modeling and novel micro-pillar and in-situ x-ray diffraction verification techniques. The inadequacies of current plasticity theories, including strain gradient formulations, will be addressed via a systematic approach in which the kinetics of cross slip and role of free surfaces and grain boundaries as sources and sinks will be systematically studied. An exciting premise in this investigation is that sub-micron and nano-scale samples may derive extraordinary strength from "dislocation-starvation." A principle outcome is that the proposed, focused interaction among several computational techniques will provide the basis for a new plasticity theory for sub-micron and nano-scale components.The broader impact of the project draws from the current industrial and scientific thrusts to understand the properties of small devices. The research is aimed at enabling small mechanical device design and development, by providing a computational tool base with which to predict the mechanical properties of components as size and structure are diminished to the sub-micron and nano-scale. Our computational and experimental findings will be packaged into an open web site for use by the academic and industrial communities - particularly those in the US and EC - and will set a precedent for comprehensive, accessible computational materials results at the sub-micron scale.The educational impact will be enhanced by investigators who are commited to participation from under-represented groups, the unique educational exchange offered by an international collaboration, and a proposed series of web-based lectures to teach the basis of each of the computational materials methods to be used in this program.