BRIGE: Anisotropic Deformation and Damage Mechanisms in Al-Mg Bi-modal Grain Size Alloy

本次bridge奖的研究目的是研究Al-Mg双模态晶粒尺寸合金的非弹性变形和损伤的物理机制。通过实验研究应变速率、微观结构、温度和各向异性等参数对损伤物理机制的影响。为了分别探讨大晶粒和纳米晶基体的变形机理，并评价两者的贡献，分别对无大晶粒和不同体积比的大晶粒试样进行了测试。由于这些材料的各向异性，试验将在不同的方向进行，以比较变形速率和机制以及强度。利用扫描电镜和透射电镜对试验前后进行微观组织分析，探讨变形机理和微观组织演变。将开发基于微观结构的本构模型来模拟这种材料的非弹性变形。如果成功，本研究结果将为研究Al-Mg双模态晶粒尺寸合金的多晶塑性和损伤机制以及本构方程提供基础科学和技术。这些本构方程将考虑微观结构效应，并将能够确定在不同方向上的变形率。此外，这些研究的结果将为微观结构非均匀各向异性材料的循环疲劳和损伤研究提供必要的框架、实验技术和知识。这些知识将有助于社区设计更可靠、更具成本效益和更智能的结构。通过拓展妇女、少数民族和代表性不足的群体，吸引k-12学生接受科学和技术领域的高等教育，并通过系统渠道丰富研究生和本科课程，增强了该项目更广泛的社会影响。

The research objective of this BRIGE award is to investigate physical mechanisms of inelastic deformation and damage in Al-Mg bi-modal grain size alloys. Effect of different parameters such as strain rate, microstructure, temperature, and anisotropy on physical mechanisms of damage will be investigated through experiment. In order to explore the deformation mechanisms of larger grains and nano-crystalline matrix separately and to be able to evaluate the contribution of these two, specimens without large grains and with different volume ratios of large grains are tested. Due to anisotropic nature of these materials, the tests will be conducted in different orientations to compare the deformation rates and mechanisms as well as strength. Microstructural analysis will be conducted before and after test using SEM and TEM to explore deformation mechanisms and microstructural evolution. Micro-structural based constitutive models will be developed for this material to model inelastic deformation. If successful, the results of this research will provide fundamental science and technology on polycrystalline plasticity and damage mechanisms as well as constitutive equations for Al-Mg bi-modal grain size alloys. These constitutive equations will take the microstructural effect into account and will be capable of determining the deformation rates in different orientations. In addition, the results from these studies will provide the necessary framework, experimental techniques, and knowledge to allow investigations of cyclic fatigue and damage in micro structurally non-uniform anisotropic material. This knowledge will assist the community in designing more reliable, cost effective and intelligent structures. Broader societal impact of this project is enhanced by outreaching women and minorities and underrepresented groups, attracting k-12 students to higher education in the area of science and technology and enriching graduate and undergraduate curriculum through systematic channels.