Collaborative Research: Mesoscopic Defect Field Interactions in Materials with High Number Density of Interfaces

晶体材料的变形行为是非常复杂的，由于描述其结构组成的长度尺度的层次结构。界面在这些不同的长度尺度上连接不同的晶体结构或材料相。晶体缺陷与界面的相互作用是导致应用规模上材料行为突现的主要原因。缺陷和界面通过多个尺度到日常应用的更高尺度的集体相互作用在实验上非常具有挑战性，并且还没有使用计算机模拟捕获到所需的复杂性。这对于理解复杂材料的行为是一个重大障碍，其中高密度的特定界面有助于实现上级功能和/或机械性能。本研究旨在通过利用和进一步推进原子到连续体尺度的方法来研究超晶格和超材料，以应对这一挑战。预计这项研究将大大促进材料力学和计算材料科学领域，对快速发展的计算材料设计领域产生相应的影响，这将促进国家的健康，繁荣和福利。这项工作还预计将通过对本科生进行高性能计算培训、加强研究生课程以及向更广泛的社区传播代码，产生更广泛的影响。超晶格和超材料代表了两种新兴的材料系统，它们的特殊性质来自结构而不是成分。超晶格和超材料具有有序的周期性界面和结构，它们提供了模型系统，可以系统地研究界面对演化缺陷结构的集体作用。这项合作的目标是通过使用先进的并行原子连续体（CAC）方法研究这类特殊的材料系统，来展示界面和缺陷对机械性能的集体作用。预计这项研究将确定主导变形机制以及控制材料行为和潜在机制的关键结构变量，探索材料表现出从韧性到脆性行为转变的临界长度尺度或结构参数，并研究控制这些材料系统中塑性流动和断裂行为的基本现象。该奖项反映了NSF的法定基金会的使命是履行其使命，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价，被认为值得支持。

Deformation behavior of crystalline materials is highly complex, owing to a hierarchy of length scales that describes their structural makeup. Interfaces link distinct crystal structures or material phases at these various length scales. The interactions of crystalline defects with interfaces are chiefly responsible for the emergent material behavior at the application scale. The collective interactions of defects and interfaces through multiple scales up to the higher scale of everyday applications have been extremely challenging to resolve experimentally and have also not been captured using computer simulations to the desired sophistication. This is a significant obstacle to the understanding of the behavior of complex materials, where high density of specific interfaces is instrumental in achieving superior functional and/or mechanical properties. This research aims to address this challenge through the study of superlattices and metamaterials by exploiting and further advancing an atomistic-to-continuum scale method. It is expected that this research will significantly promote the fields of mechanics of materials and computational materials science, with commensurate impact on the rapidly developing field of computational materials design, which will advance national health, prosperity, and welfare. This work is also expected to have substantial broader impact through training of undergraduate students in high-performance computing, graduate curriculum enhancements, and dissemination of codes to the wider community. The project will also reach out to engage students from underrepresented groups.Superlattices and metamaterials represent two emerging material systems that derive their exceptional properties from structure rather than composition. With their well-ordered periodic interfaces and structure, superlattices and metamaterials provide model systems amenable to systematic study of the collective role of interfaces on evolving defect structures. The goal of this collaborative effort is to demonstrate the collective role of interfaces and defects on mechanical properties by studying this special class of material systems by using an advanced Concurrent Atomistic-Continuum (CAC) approach. It is expected that this research will identify the dominant deformation mechanisms as well as the key structural variables that control the materials behavior and the underlying mechanisms, explore the critical length scale or structural parameters at which the materials exhibit a transition from ductile to brittle behavior, and investigate the fundamental phenomena that control the plastic flow and fracture behaviors in these material systems.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.