SGER: A Novel Method for In-Situ Fatigue Experiments

小行星9416775 这是一项高风险的小额资助，用于探索性研究（SGER），在透射电子显微镜下进行原位疲劳实验。 经典的金属疲劳现象是知之甚少，部分原因是位错动力学的反向变形还没有得到表征。 在循环变形过程中直接观察位错，例如在透射电子显微镜中原位循环或反向塑性变形试验中观察到的，仅取得了有限的成功。 这个问题是与薄箔屈曲时，所施加的拉伸或剪切应力是反向的。 分析表明，在垂直方向上交替施加拉应力可以逆转位错的运动，从而避免箔片的屈曲。 一个新的标本保持器已设计的主要研究者进行这样的机械测试原位的透射电子显微镜。 一系列原位反向变形疲劳试验将运行，并应提供新的见解反向变形现象。 %金属合金的疲劳会导致工业机械、运输系统和相关基础设施领域中使用的金属合金部件发生意外故障。 这项研究应能增进对这一领域的了解。 ***

9416775 Kassner This is a high-risk, small grant for exploratory research (SGER) to perform in-situ fatigue experiments in the transmission electron microscope. The classic metal-fatigue phenomenon is poorly understood, partially because the dislocation dynamics of reversed deformation has not been characterized. Only limited success has been achieved with direct observation of dislocations during cyclic deformation, such as observed in in-situ cyclic or reversed plastic deformation tests in the transmission electron microscope. The problem is associated with buckling of thin foils when the applied tensile or shear stress is reversed. Analysis shows that dislocation movement can be reversed by tensile stressing in alternating perpendicular directions, and buckling of the foil can be avoided. A new specimen holder has been designed by the principal investigator for performing such mechanical tests in-situ in the transmission electron microscope. A series of in-situ reversed deformation fatigue tests will be run and should provide new insights into reversed deformation phenomena. %%% Fatigue of metal alloys can lead to unanticipated failure of metal alloy components used in industrial machinery, transportation systems, and related infrastructure areas. This research should provide improved understanding in this field. ***