Experimental Characterization of Deformation Mechanisms in Magnesium Rare Earth Alloys

镁稀土合金变形机制的实验表征

基本信息

批准号：
1709865
负责人：
Kevin Hemker
金额：
$ 52.87万
依托单位：
Johns Hopkins 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：
2017-07-01 至 2020-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709865&HistoricalAwards=false
关键词：
Experimental Characterization Deformation Mechanisms Magnesium

项目摘要

Nontechnical abstract: The overall versatility, deployability and energy efficiency of modern manned and autonomous vehicles are inversely related to their weight. Magnesium (Mg) is nearly four times lighter than steel and its ultra-low density and high specific strength make Mg alloys attractive lightweighting materials for commercial and defense platforms. However, the use of Mg has been inhibited by its limited ductility and formability, which is attributed to strong plastic anisotropy that results from its hexagonal crystal structure. Recent gains in formability have been achieved through rare earth alloying, and this project will provide a detailed understanding of the influence that these rare earth elements have on the atomic-scale mechanisms that govern ductility and formability. The insights obtained from this experimental study will accelerate alloy development and help promote cost-effective lightweighting in a wide variety of automotive, military and aerospace applications. Collaborations will provide meaningful STEM educational and career advancement opportunities, and participation in SABES will offer JHU researchers a chance to personally interact with and give Baltimore elementary school students a unique perspective on STEM activities. Technical Abstract:The scientific merit of this study is predicated in our desire to see and understand the deformation mechanisms that underpin the mechanical response of Mg alloys and to elucidate the fundamental role that rare earth elements have in increasing ductility and improving formability. The experimental tasks to be undertaken include: (i) identification of active slip systems in Mg-RE alloys, (ii) meso-scale characterization of dislocation morphologies and microstructures, (iii) atomic-scale characterization of dislocation cores, and (iv) identification of the factors influencing twin nucleation and growth. SEM-based EBSD mapping and STEM observations and TEM-based bright field, weak-beam dark field, HREM, and STEM imaging and nanoscale orientation and elastic strain mapping will be employed. The experimental data collected will be digitally archived and used to promote Integrated Computational Materials Science and Engineering (ICMSE) as envisaged by the Materials Genome Initiative (MGI).

非技术摘要：现代载人和自动驾驶汽车的总体多功能性，可部署性和能源效率与其重量成反比。镁（MG）比钢的镁（MG）近四倍，其超低密度和高特异性强度使MG合金具有吸引人的商用和防御平台的轻巧材料。然而，MG的使用受到其有限的延展性和形成性的抑制，这归因于其六角形晶体结构引起的强塑性各向异性。最近通过稀土合金化实现了可表现性的最新提高性，该项目将详细了解这些稀土元素对控制延展性和形成性的原子尺度机制的影响。从这项实验研究中获得的见解将加速合金开发，并有助于在各种汽车，军事和航空航天应用中促进具有成本效益的轻巧。合作将提供有意义的STEM教育和职业发展机会，参与SABES将为JHU研究人员有机会与Baltimore小学学生亲自互动并为STEM活动提供独特的观点。技术摘要：这项研究的科学优点是基于我们希望看到和理解基于MG合金机械响应的变形机制的愿望，并阐明了稀土元素在增加延展性和提高表现性中的基本作用。要执行的实验任务包括：（i）识别MG-RE合金中的活动滑移系统，（ii）脱位形态和微观结构的中尺度表征，（III）原子级曲面表征对位错核的表征以及（IV）影响双胞胎成核和生长的因素。将采用基于SEM的EBSD映射和茎观测以及基于TEM的明亮场，弱光束暗场，HREM和STEM成像以及纳米级取向以及弹性应变映射。收集到的实验数据将进行数字存档，并用于促进材料基因组计划（MGI）设想的综合计算材料科学与工程（ICMSE）。