NSF/Sandia: Collaborative Research: Adaptive Hierarchical Multiscale Framework for Modeling the Deformation of Ultra-Strong Nano-Structured Materials

纳米结构材料在需要高强度和延展性的应用中具有极大的吸引力。这两个领域是：(1)用于未来航空航天应用的纳米层状复合材料，要求高强度-重量比；(2)下一代互连和封装组件在未来几代电子设备。虽然原子分子动力学（MD）模拟是研究纳米尺度（不考虑电子结构）变形现象的最可靠工具，但它们仅限于非常小的体积和很短的模拟时间。同样，位错动力学模拟在解决缺陷的核心结构和在没有特别假设的情况下纳入位错成核事件的能力方面受到限制。我们计划开发一种自适应分层多尺度框架（AHMF），其中根据模型误差估计器自适应地选择适当的尺度和物理。利用这一框架，我们计划研究两类纳米结构材料的变形特性：多晶纳米孪晶铜互连材料和多层纳米复合材料。我们将这些新工具应用于bcc/fcc纳米层状材料的设计，以及具有超高强度和正常电导率的纳米孪晶铜互连线的开发，使其可以作为独立的互连线。

Abstract Nano-structured materials are extremely attractive for applications requiring high strength and ductility. Two such areas are: (1) nano-layered composites for future aerospace applications demanding high strength-to-weight ratios; and (2) next-generation interconnect and packaging components in future generations of electronic devices. While atomistic Molecular Dynamics (MD) simulations are the most reliable tools for investigating deformation phenomena at the nano-scale (in absence of electronic structure considerations), they are limited to very small volumes and short simulation times. Likewise, dislocation dynamics simulations are limited in the ability to resolve the core structure of defects and to incorporate dislocation nucleation events without ad hoc assumptions. We plan to develop an adaptive hierarchical multiscale framework (AHMF) , where appropriate scale and physics are selected adaptively based on model error estimators.. Using this framework, we plan to investigate the deformation characteristics of two classes of nano-structured materials: polycrystalline nano-twinned copper inter-connects, and multi-layer nano-composites. We will apply these new tools to the design of bcc/fcc nano-layered materials, and the development of nano-twinned Cu interconnect lines with ultra-high strength and normal conductivity so that they can act as free standing interconnects.