NIRT: Mechanical Behavior of Bulk Nanostructured Materials

这项拨款用于研究使用不同技术（如低温研磨、严重塑性变形和电沉积）生产的大块纳米晶体材料的机械性能。一个主要的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。具有不同晶体结构的纯金属（FCC， BCC和HCP）将被考虑与超塑性Zn-22%Al共析以及商业合金（如Inconel和超细晶结构钢）一起使用。目的是利用新的压痕技术，在电镜下对大块纳米晶试样进行拉伸、剪切和疲劳试验。在实验研究的基础上，将建立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。纳米材料的力学行为研究的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，这些材料可能允许在异常高速率或低温下形成超塑性的可能性，以及它们在循环载荷下的响应。将探讨化学、机械和电磁技术的可能应用。除了提供对纳米晶体材料力学行为的更好理解，以及如何在工程应用中利用纳米晶体材料的含义之外，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项目，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.