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

本次布里奇奖的研究目的是研究Al-Mg双峰晶粒度合金的非弹性变形和损伤的物理机制。通过实验研究了应变率、微结构、温度、各向异性等参数对损伤物理机制的影响。为了分别探讨大颗粒和纳米晶基质的变形机理，并能够评价两者的贡献，对不含大颗粒和不同大颗粒体积比的试件进行了试验。由于这些材料的各向异性，将在不同的方向进行试验，以比较变形速度、变形机理和强度。利用扫描电子显微镜和透射电子显微镜对试验前后的组织进行分析，探讨变形机制和组织演变。该材料将建立基于细观结构的本构模型来模拟非弹性变形。如果研究成功，将为Al-Mg双峰晶粒度合金的多晶塑性和损伤机理以及本构方程的研究提供基础性的科学和技术。这些本构方程将考虑微结构的影响，并将能够确定不同方向的变形速率。此外，这些研究的结果将提供必要的框架、实验技术和知识，以便能够研究微观结构非均匀各向异性材料的循环疲劳和损伤。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。通过向妇女、少数群体和代表性不足的群体伸出援手，吸引K-12学生接受科学和技术领域的高等教育，并通过系统的渠道丰富研究生和本科生的课程，该项目的更广泛的社会影响得到了加强。

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.