Understanding Dislocation Motion and Plasticity via First Principles Simulations Towards Manufacturing of High Ductility Magnesium Alloys

通过高延展性镁合金制造的第一原理模拟了解位错运动和塑性

基本信息

批准号：
2032483
负责人：
Yantao Shen
金额：
$ 46.92万
依托单位：
Board of Regents, NSHE, obo University of Nevada, Reno
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2032483&HistoricalAwards=false
关键词：
Understanding Dislocation Motion Plasticity via

项目摘要

This grant supports fundamental research that facilitates manufacturing of ductile magnesium alloys. Magnesium alloys are the lightest structural materials and they are desirable for automotive and aerospace applications where improved energy efficiency becomes increasingly crucial. However, the limited room temperature ductility of magnesium alloys poses one of the major challenges to broad engineering application of these materials. Cold processing of magnesium at room temperature results in cracking or fracture. Hence, warm processing at elevated temperatures is typically used for industrial manufacturing, but this increases energy cost. To improve the ductility, expensive rare earth elements have been added to magnesium, but this is undesirable because of the high cost and uncertain availability of rare earths. This research project incorporates computational and experimental studies to search for inexpensive and readily available alloying elements for manufacturing new magnesium alloys with superior ductility. The results obtained from this work enables low-cost manufacturing of magnesium alloys which impacts the US economy and the environment. The project also promotes education of Integrated Computational Materials Engineering principles at undergraduate and graduate levels, as well as diversity by involving women and underrepresented minorities in disciplines of Science, Technology, Engineering and Math.Easy dislocation slip systems on the basal and prismatic planes in magnesium are unable to accommodate strain components along the c-axis of the hexagonal close-packed crystal structure. This leads to the limited ductility of magnesium at room temperature. The pyramidal c+a dislocations are able to accommodate c-axis strains, but their critical resolved shear stresses are one to two orders of magnitude higher than those of prismatic and basal dislocations. Consequently, under conventional deformation conditions, the density of c+a dislocations is insufficient to meet the criterion of strain accommodation. This project integrates first-principles hierarchical high-throughput-screening and experimental studies to identify alloying elements that are able to reduce the energy barrier to nucleation and glide of the c+a dislocations in Mg alloys. This is achieved by calculating through first principles simulations how alloying elements influence the landscape of generalized stacking fault energy which describes the energy barrier to dislocation glide. After suitable candidate elements are identified, magnesium alloys are synthesized by ingot casting. Channel die compression is carried out to fabricate samples with refined grains for tensile and compressive tests to determine their mechanical behavior. Dislocation structures are characterized by transmission electron microscopy. The project provides a new, physics-based strategy to develop novel high ductility magnesium alloys, which can be processed into components of useful shapes by rolling, drawing and stamping.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该赠款支持促进延性镁合金制造的基本研究。镁合金是最轻的结构材料，对于提高的能源效率变得越来越重要的汽车和航空航天应用是可取的。但是，镁合金的室温有限构成了这些材料的广泛工程应用的主要挑战之一。在室温下对镁的冷处理会导致破裂或断裂。因此，通常将温度升高的温暖处理用于工业制造，但这会增加能源成本。为了改善延展性，镁含量昂贵的稀土元素已添加到镁中，但这是不可取的，因为稀土的成本高和不确定的可用性。该研究项目结合了计算和实验研究，以寻找廉价且容易获得的合金元素，以制造具有优质延展性的新镁合金。从这项工作中获得的结果使镁合金的低成本生产影响了美国经济和环境。 The project also promotes education of Integrated Computational Materials Engineering principles at undergraduate and graduate levels, as well as diversity by involving women and underrepresented minorities in disciplines of Science, Technology, Engineering and Math.Easy dislocation slip systems on the basal and prismatic planes in magnesium are unable to accommodate strain components along the c-axis of the hexagonal close-packed crystal structure.这导致镁在室温下的延展性有限。锥体C+A位错能够适应C轴菌株，但是它们的临界剪切应力比棱柱形和基础位错方高一到两个数量级。因此，在常规变形条件下，C+A位错的密度不足以满足应变适应的标准。该项目整合了第一原理等级高通量筛选和实验研究，以鉴定能够减少毫克合金中C+A位错的能量屏障的合金元素。这是通过通过第一原理模拟计算的合金元件如何影响广义堆叠断层能量的景观来实现的，该局景描述了脱位滑行的能量障碍。鉴定出合适的候选元件后，通过铸币铸造合成镁合金。进行通道模具压缩以制造具有精制晶粒的样品，以进行拉伸和压缩测试，以确定其机械行为。位错结构的特征是透射电子显微镜。该项目提供了一种新的基于物理的策略，以开发新型高延展性镁合金，可以通过滚动，绘画和踩踏来将其处理成有用形状的组成部分。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来获得支持的。