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

该研究目标是联合收割机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，以实验研究Al-Mg合金中的位错塑性，表现出锯齿状流动和Portevin-Le Chatelier（PLC）不稳定性。该项目的主要目的是揭示三维位错结构在动态应变时效中的确切作用，该动态应变时效限制了一类重要的汽车级AA 5xxx材料的延展性。实验工作将集中在三维中尺度缺陷配置的成像，使用电子断层扫描仪之前和之后的定量原位nanocompression和nanotension测试内的透射电子显微镜（TEM）。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化。 这些数据将首次提供对三维位错网络的老化特性和老化动力学的洞察，以增加对PLC效应在成形模拟中的介观建模的洞察力。这项研究结合了电子显微镜和纳米力学实验中最先进的技术，也将为设计Al-Mg合金的成分和应变路径提供实验基础。 由于研究导致新的实验技术，它们将支持为TEM研究生课程建立一个电子断层摄影先进实验室，并支持与提高妇女和少数民族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.