Collaborative Research: Computational and Experimental Study of Alloying Effects on <c+a> slip in Mg

合作研究：合金化效应的计算和实验研究

• 批准号: 1709151
• 负责人: K. Sharvan Kumar
• 金额: $ 26.7万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709151&HistoricalAwards=false
• 关键词: Collaborative; Research; Computational; Experimental; Study

Nontechnical Summary:By virtue of their low density, Magnesium (Mg) and Mg-rich alloys are of significant interest in lightweight vehicle technology. However the ability to form these materials into useful shapes at ambient temperature has been the Achilles heel to widespread implementation. The room temperature formability and damage tolerance are essential to making the cost of Mg alloys competitive with those of aluminum alloys and steels. These properties rely on the ease of plastic deformation, a phenomenon that is mediated by atomic level processes. This research effort provides a fundamental understanding of how the atomic processes, responsible for enhanced formability, can be facilitated through addition of alloying elements. Furthermore, the integrated computational/experimental methodology developed by this program is a crucial step towards physics-based predictive alloy design compared to the traditional empirical approach based on trial and error and can be applied to a range of other metallic systems with similar crystal structure, such as technologically important Ti and Zr alloys. Moreover, the education and outreach component of this program, are aimed at (1) incorporating computational modeling in classroom to enhance learning of difficult concepts, (2) preparing materials science and engineering students for future careers with an increased importance of computational modeling and (3) fostering enthusiasm about Science, Technology Engineering and Math (STEM) fields in students, particularly from underrepresented groups. This project has an outreach program component in collaboration with the college of Engineering at the Ohio State University.Technical Summary:The overarching goal of this program is to enhance the room temperature deformability of Mg alloys. In pursuit of the above goal, this project aims to activate the c+a slip mode through favorable alloying. Electronic-structure calculations of c+a dislocation cores will be used to (1) Identify solutes that would stabilize the glissile core geometry of the c+a edge dislocations (2) Study the effect of candidate elements on the stability and cross-slip rate of c+a screw dislocations. Elements that promote the slip of edge segments without compromising the motion of screw segments will be suggested as viable candidates. The consequence of the theoretical alloying suggestions will be evaluated experimentally by (3) making single crystals of the proposed alloys (4) measuring stress-strain curves and (5) characterizing dislocation structure evolution. The outcome will provide new understanding of solute effects on easier activation of non-basal deformation modes in Mg that can then enhance room temperature ductility of Mg alloys, thereby increasing the widespread use of these lightweight alloys.

非技术摘要：镁和富镁合金密度低，在轻量化汽车技术中引起了极大的兴趣。然而，在环境温度下将这些材料形成有用形状的能力一直是广泛应用的致命弱点。镁合金的室温成形性和损伤容限是使其成本与铝合金和钢材竞争的关键。这些性能依赖于塑性变形的简易性，这是一种由原子水平的过程调节的现象。这项研究工作提供了一个基本的理解，即如何通过添加合金化元素来促进提高成形性的原子过程。此外，与传统的基于试错的经验方法相比，本程序开发的计算/实验一体化方法是迈向基于物理的预测合金设计的关键一步，并可应用于一系列具有类似晶体结构的其他金属系统，如具有重要技术意义的钛和锆合金。此外，该计划的教育和推广部分旨在(1)将计算建模纳入课堂，以加强对困难概念的学习，(2)随着计算建模的重要性增加，为材料科学和工程专业的学生未来的职业生涯做好准备，以及(3)培养学生对科学、技术工程和数学(STEM)领域的热情，特别是来自代表性不足的群体。该项目有一个与俄亥俄州立大学工程学院合作的推广计划部分。技术总结：该计划的主要目标是提高镁合金的室温变形能力。为了实现上述目标，本项目旨在通过有利的合金化来激活c+a滑移模式。C+a位错核的电子结构计算将被用来(1)确定稳定c+a刃位错的闪光核几何形状的溶质(2)研究候选元素对c+a螺型位错稳定性和交叉滑移率的影响。在不影响螺杆段运动的情况下促进边缘段滑移的元件将被建议为可行的候选元件。理论合金化建议的结果将通过(3)制备所建议的合金的单晶，(4)测量应力-应变曲线和(5)表征位错结构的演变来实验地评估。这一结果将对溶质效应提供新的理解，从而更容易地激活镁合金中的非基本变形模式，从而提高镁合金的室温塑性，从而增加这些轻质合金的广泛使用。