CAREER: Fundamental Insights into Deformation of Lightweight Alloys from Discovery-Class Atomistic Simulations

该奖项由2009年美国复苏和再投资法案（公法111-5）资助，其研究目标是通过使用最先进的原子模拟方法，如加速分子动力学（AMD），了解超轻单晶六方密排镁锂（Mg-Li）合金的变形科学。虽然传统的分子动力学技术使我们能够在纳秒时间尺度上研究材料的变形机制，AMD和其他技术允许在实验相关的时间尺度上研究包含重要微观结构缺陷的大型材料系统。在许多情况下，实验相关的时间尺度比分子动力学时间尺度大至少六个数量级。为了实现这一目标，我们将探讨一些基本问题与缺陷的相互作用在微观结构的长度尺度和澄清疲劳过程中的镁锂合金使用计算建模。可供参考的材料包括基本组件和基本机制的目录、为这项工作开发的建模和分析工具、研究结果的文档、学生教育以及研究生和本科生的研究经验。镁的密度约为铝的三分之二。用镁合金代替汽车的许多零部件，可以减轻汽车重量，降低燃料消耗约30%，并大大减少二氧化碳的排放。锂是已知的最轻的金属，它广泛地溶解在镁中。因此，如果我们克服诸如其室温机械性能不稳定的基本问题，则将Mg与Li合金化可以产生革命性的、重量最轻的结构合金。我们的工作将在这一重要领域有所启发。影响的其他领域包括通过盲人学生的数字图书馆弥合视力和盲人学生之间的知识鸿沟，增加高中，本科和研究生参与研究，通过与我们的同事在国家实验室，会议演示文稿和期刊出版物的合作，增强学生研究人员的研究和教育经验，并迅速将AMD等最先进的研究工具传播到课堂课程中。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The research objective of this award is to understand deformation science in ultralight, single-crystal, hexagonal close-packed magnesium-lithium (Mg-Li) alloys by using the state-of-the-art atomistic simulation methods such as accelerated molecular dynamics (AMD). While the conventional molecular dynamics technique allows us to study deformation mechanisms in materials over nano-second timescales, AMD and other techniques allow study of large material systems containing important microstructural defects over experimentally relevant time scales. In many instances, the experimentally relevant timescales are at least six orders of magnitude larger than molecular dynamics time scales. In pursuit of this goal, we will explore some fundamental problems associated with defect interactions at the microstructural length scale and clarify fatigue processes in Mg-Li alloys using computational modeling. Deliverables include a catalog of fundamental components and basic mechanisms, modeling and analysis tools developed for this work, documentation of research results, student education, and research experiences for graduate and undergraduate students.Mg is about two-thirds as dense as aluminum. Replacing many automobile components with Mg alloys will reduce automobile weight, decrease the fuel consumption by about 30%, and cut down carbon-dioxide emission substantially. Li is the lightest metal known and it dissolves extensively in Mg. Thus, alloying Mg with Li can produce revolutionary, lightest weight structural alloys if we overcome fundamental issues such as instability of its room temperature mechanical properties. Our work will shed light in this important area. Other areas of impact include bridging the knowledge-divide between sighted and blind students through a digital library for the blind students, increasing the participation of high school, undergraduate, and graduate students in research, enhancing research and education experiences for student researchers through collaboration with our colleagues at national laboratories, conference presentations, and journal publications, and disseminating state-of-the-art research tools like AMD into the classroom curriculum rapidly.