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，但金属结构部件何时何地损坏和失效很难预测，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，这些材料容易通过形成空隙和局部剪切带而塑性变形。这些空隙的产生受到由包含多晶金属的单晶构成的聚集体复合物的内部构造的强烈影响。高纯度的金属经常在单晶之间的边界处形成空隙，但不知道为什么。该设计材料革命和工程我们的未来（DMREF）奖支持高纯度金属中基于空隙的韧性损伤的基础研究，以使材料的制造能够显著降低空隙形成的倾向。此外，该项目还将促进与空军研究实验室的合作，以寻求用于战略目的的新材料和制造技术。这个高度合作的项目还将使学生有机会参与三个校区，空军研究实验室和能源实验室的几个部门，以协助教育下一代科学家和工程师的战略重要学科。设计材料界面以抵抗拉伸变形过程中形成的空隙将是对材料基因组计划的重大贡献。该奖项致力于控制多晶金属的特征和缺陷特性以及内部应力状态，以防止失效。韧性损伤除了局部剪切带外，一般还包括孔洞成核、长大和合并的过程。该项目是一个新的三维样品设计的杆和板形式的材料，这将是一个替代一般的结构部件的大变形。由于体心立方钽具有在极端环境下使用的潜力，因此选择高纯难熔体心立方钽作为模型材料。已知这种材料主要在晶界处形成空隙，并且将成为通过先进制造工艺进行材料设计的焦点。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的高度互动元素，分子动力学模拟，一致的塑性和理论发展，微观尺度多晶模拟和宏观尺度损伤模拟组件设计。该方法的亮点是通过机器学习进行不确定性量化，用于大型实验和模拟数据集的自洽合并，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，生产出的材料比接收和退火状态下的材料减少30%的损坏。该项目由工程局（ENG）的土木、机械和制造创新部（CMMI）共同资助，数学和物理科学局（MPS）的材料研究司（DMR）和数学科学司（DMS），该奖项反映了NSF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.