DMREF/Collaborative Research: Grain Interface Functional Design to Create Damage Resistance in Polycrystalline Metallic Materials

尽管多晶金属材料在日常生活中无处不在，但金属结构部件在何时何地损坏和失效是难以预测的，这通常会导致过度设计。一种形式的损伤-延性损伤-发生在材料中，这些材料容易因形成空洞和局部剪切带而发生塑性变形。这些孔洞的形成受到由多晶金属组成的单晶复合材料的内部结构的强烈影响。高纯度金属经常在单晶之间的边界处形成空洞，但原因尚不清楚。DMREF （design Materials to Revolutionize and engineering our Future）奖项支持对高纯度金属中基于孔洞的韧性损伤进行基础研究，从而能够制造出可显著降低孔洞形成倾向的特定应用材料。此外，该项目将促进与空军研究实验室的合作，为战略目的追求新材料和制造技术的设计。这个高度合作的项目还将使学生有机会参与到三个校区、空军研究实验室和几个能源部实验室中，以协助培养具有重要战略意义的学科的下一代科学家和工程师。设计材料界面以抵抗拉伸变形过程中空洞的形成将对材料基因组计划做出重大贡献。该奖项针对多晶金属设计和制造中防止失效的特征和缺陷特征以及内应力状态的控制。除局部剪切带外，延性损伤一般包括空洞形核、生长和聚并过程。这个项目是一个新的三维样品设计的棒材和板材形式的材料，这将是一个大变形的一般结构部件的替代品。选择高纯度耐火体心立方钽作为模型材料，因为它具有在极端环境下使用的潜力。已知这种材料主要在晶界处形成空洞，并将通过先进的制造工艺成为材料设计的焦点。材料设计过程将包括在不同应变率和温度下的纳米、微观和宏观尺度实验、分子动力学模拟、热力学一致的塑性和理论发展、微观尺度的多晶体模拟和宏观尺度的部件设计损伤模拟等高度交互的元素。该方法的亮点是通过机器学习进行不确定性量化，以实现大型实验和模拟数据集的自一致整合，以指导材料设计和制造过程。该项目的目标是设计一种制造工艺，以生产比接收和退火状态下减少30%损伤的材料。该项目由工程理事会（ENG）的土木、机械和制造创新司（CMMI）、数学和物理科学理事会（MPS）的材料研究部（DMR）和数学科学部（DMS）以及刺激竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Even though polycrystalline metallic materials are ubiquitous in daily life, when and where metallic structural components damage and fail is difficult to predict, which generally leads to overdesign. One form of damage – ductile damage – takes place in materials which are easily plastically deformed by formation of voids and localized shear bands. The initiation of these voids is strongly influenced by the internal constitution of the aggregate composite made up of single crystals comprising the polycrystalline metal. High-purity metals often form voids at the boundaries between single crystals, but it is not known why. This Designing Materials to Revolutionize and Engineer our Future (DMREF) award supports the fundamental study of voids-based ductile damage in high-purity metals to enable the manufacture of materials for specific applications with significantly reduced propensity for void formation. In addition, this project will facilitate collaboration with the Air Force Research Laboratory to pursue design of new materials and manufacturing techniques for strategic purposes. This highly collaborative project will also allow students the opportunity to engage on three campuses, the Air Force Research Laboratory, and a couple of Department of Energy Laboratories to assist in educating the next generation of scientists and engineers in strategically important disciplines. Designing material interfaces to resist formation of voids during tensile deformation will be a significant contribution to the Materials Genome Initiative. This award addresses control of feature and defect character as well as the internal stress state for the design and manufacture of polycrystalline metals against failure. Ductile damage generally includes the processes of void nucleation, growth, and coalescence in addition to localized shear banding. This project is for a new three-dimensional sample design for both rod and plate forms of material, which will be a surrogate for a general structural component for large deformation. High-purity refractory body-centered cubic tantalum is selected as the model material due to its potential for extreme environment use. This material is known to form voids predominantly at grain boundaries and will be the focal point of material design through advanced manufacturing processes. The material design process will include the highly interactive elements of nano, micro and macro-scale experiments at varying strain rates and temperatures, molecular dynamics simulations, thermodynamically consistent plasticity and theory development, micro-scale polycrystal simulations, and macro-scale damage simulations for component design. The highlight of the approach is the uncertainty quantification via machine learning for self-consistent consolidation of large experimental and simulation datasets to guide material design and manufacturing process. The goal of this project is to design a manufacturing process to produce material which reduces damage by 30% over that in the as-received and annealed state.This project is jointly funded by the Division of Civil, Mechanical and Manufacturing Innovation (CMMI) in the Directorate for Engineering (ENG), the Divisions of Materials Research (DMR) and Mathematical Sciences (DMS) in the Directorate for Mathematical and Physical Sciences (MPS), and the Established Program to Stimulate Competitive Research (EPSCoR).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.