NIRT: Mechanical Behavior of Bulk Nanostructured Materials

该基金用于研究采用不同技术（如低温研磨、剧烈塑性变形和电沉积）生产的块状纳米晶材料的机械性能。一个主要目标是阐明和理解纳米材料的机械性能，特别是包括它们的强度，延展性，蠕变，超塑性和疲劳。将考虑具有不同晶体结构（FCC、BCC和HCP）的纯金属与超塑性Zn-22%Al共析体以及商业合金（例如Inconel和超细晶粒结构钢）一起沿着。我们的目标是使用新的压痕技术在电子显微镜沿着与拉伸，剪切和疲劳测试块体纳米晶样品原位。沿着实验研究，将开发基于原子模拟的计算模型来预测机械响应并与实验结果相关联。对纳米材料力学行为的研究重点是其潜在的高强度，在中低温下通过晶界扩散提高蠕变速率的可能性，这些材料在极高速率或低温下允许超塑性成形的可能性，以及它们在循环载荷下的响应。该项目将探索化学、机械和电磁技术的可能应用。除了提供对纳米晶材料力学行为的更好理解，以及对如何在工程应用中利用纳米晶材料的影响外，该项目还将为研究生和本科生提供有用的教育经验，这将有助于他们的培训、技能、知识和职业生涯。来自三个不同学术机构的五名研究人员协调研究计划，计划与洛斯阿拉莫斯国家实验室和劳伦斯利弗莫尔国家实验室等国家实验室建立合作关系。

This grant is on a study of the mechanical properties of bulk nanocrystalline materials produced using different techniques such as cryomilling, severe plastic deformation and electrodeposition. A major objective is to elucidate and understand the mechanical properties of nc-materials, particularly including their strength, ductility, creep, superplasticity, and fatigue. Pure metals with different crystal structures (FCC, BCC and HCP) will be considered along with superplastic Zn-22%Al eutectoid as well as commercial alloys such as Inconel and ultra-fine grained structural steel. The goal is to use novel indentation technique in-situ in electron microscope along with tensile, shear and fatigue tests on bulk nanocrystalline samples. Along with the experimental studies, computational models based on atomistic simulations will be developed to predict the mechanical response and to correlate with the experimental results. The focus of the research on mechanical behavior of nc-materials is on their potentially high strength, the possibility of enhanced creep rates at moderate to low temperatures by grain boundary diffusion, the possibility that these materials may permit superplastic forming at exceptionally high rates or low temperatures, and their response under cyclic loading. The possible applications for chemical, mechanical and electromagnetic technologies will be explored.In addition to providing improved understanding of mechanical behavior in nanocrystalline materials, with implications for how they can be exploited in engineering applications, the program will provide graduate and undergraduate students with useful educational experiences that will contribute to their training, skills, knowledge, and professional careers. Five investigators at three different academic institutions coordinate the research program with plans to establish collaborations with national laboratories such as Los Alamos National Laboratory and Lawrence Livermore National Laboratory.