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

这项学术联络与工业（GOALI）奖的研究目标将结合两种先进的电子显微镜技术，电子断层扫描和透射电子显微镜（TEM）内的原位力学测试，实验研究具有锯齿状流动和Portevin-Le Chatelier （PLC）不稳定性的Al-Mg合金的位错塑性。该项目的主要目的是揭示三维位错结构在动态应变老化中的精确作用，这种结构限制了一类重要的汽车级AA5xxx材料的延展性。实验工作将集中于在透射电子显微镜（TEM）内进行定量原位纳米压缩和纳米拉伸测试前后，利用电子断层扫描对中尺度缺陷结构进行三维成像。实验将测量有和没有PLC不稳定性的Al-Mg合金中位错网络的演变。这些数据将首次提供三维位错网络的时效特征和时效动力学的见解，从而为成形模拟中PLC效应的中尺度建模提供见解。本研究结合了最新的电子显微镜技术和纳米力学实验技术，也将为设计铝镁合金的成分和应变路径提供实验依据。随着这项研究带来新的实验技术，他们将为研究生电子断层扫描课程建立一个先进的实验室，并开展与提高妇女和少数民族在科学和工程中的作用有关的推广活动。

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.