GOALI: Understanding 3D Dislocation Behavior in Al-Mg through Combined Electron Tomography and in situ TEM Nanomechanical Testing.

这项授予工业学术联系机会(GOALI)奖的研究目标将结合两种先进的电子显微镜技术，即电子断层扫描和透射电子显微镜(TEM)内的原位机械测试，以实验研究呈现锯齿状流动和Portevin-Le Chatelier(PLC)不稳定性的铝镁合金中的位错塑性。该项目的主要目的是揭示3D位错结构在动态应变时效中的精确作用，动态应变时效限制了一类重要的汽车级AA5xxx材料的塑性。实验工作将集中在利用电子层析成像技术在透射电子显微镜内进行定量的原位纳米压缩和纳米拉伸测试之前和之后的三维介观缺陷构型的成像。实验将测量有无PLC失稳时Al-Mg合金中位错网络的演化。这些数据将首次在三维上深入了解位错网络的时效特征和时效动力学，从而为在成形模拟中对PLC效应的介观模拟增加洞察力。这项研究结合了最先进的电子显微镜和纳米机械实验技术，也将为设计铝镁合金的成分和应变路径提供实验依据。随着这项研究产生新的实验技术，它们将支持建立一个高级电子断层扫描实验室，用于电子断层扫描技术研究生课程，并开展与提高妇女和少数群体在科学和工程中的作用有关的外联活动。

The research objective of this Grant Opportunity for Academic Liaison with Industry (GOALI) award will combine two advanced electron microscopy techniques, electron tomography and in situ mechanical testing inside a transmission electron microscope (TEM), to experimentally study dislocation plasticity in Al-Mg alloys exhibiting serrated flow and Portevin-Le Chatelier (PLC) instability. The main aim of the project is to uncover the precise role of the 3D dislocation structure in dynamic strain ageing that limits the ductility of an important class of automotive grade AA5xxx materials. The experimental work will center on the imaging of the mesoscale defect configuration in three dimensions using electron tomography before and after quantitative in situ nanocompression and nanotension tests inside a transmission electron microscope (TEM). The experiments will measure the evolution of dislocation networks in Al-Mg alloys with and without the PLC instability. The data will provide for the first time insight into the aging characteristics and aging dynamics of dislocation networks in three dimensions to add insights into mesoscale modeling of the PLC effect in forming simulations. This research, which combines state-of-the-art techniques in electron microscopy and nanomechanical experiments, will also provide an experimental basis for designing compositions and strain paths for Al-Mg alloys. As the research leads to new experimental techniques, they will underpin the creation of an advanced laboratory on electron tomography for a graduate TEM course and outreach activities related to increasing the role of women and minorities in science and engineering.