X-ray Laue Microscopy to Understand Fatigue Damage

X 射线 Laue 显微镜了解疲劳损伤

• 批准号: 316662945
• 负责人: Professor Dr. Christoph Kirchlechner
• 金额: --
• 依托单位: InterFace Beamline BM32 CRG-IF
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/316662945?language=en
• 关键词: ray; Laue; Microscopy; Understand; Fatigue

The influence of intrinsic and extrinsic size effects on the formation of characteristic dislocation structures during fatigue has not been studied in detail, let alone understood. In particular, the formation of dislocation structures in the vicinity of individual grain boundaries and their role in crack initiation could not be studied in detail until now, mainly due to the lack of suitable in situ characterization techniques.In the course of the first funding period of the XMicroFatigue project, a "Differential Aperture X-Ray Microscope" (DAXM) was built, which provides non-destructive access to dislocation densities, elastic strain fields and orientation with sub-micrometer resolution, while allowing the deformation of micro-objects. Bicrystalline micro bending cantilevers – each of which had a single grain boundary at the center of the sample – were subjected to cyclic loading and the resulting dislocation structures were studied. Copper was chosen as model material. Our focus was on a grain boundary that was intransparent to dislocation slip transfer.All objectives of the first funding period with respect to the construction and validation of the in situ DAXM have been successfully achieved. The microscope as well as evaluation routines are available to the Laue user community. With respect to fatigue of a grain boundary that is intransparent to dislocation motion, all necessary experiments have been successfully completed, but the evaluation of the large data sets is ongoing and is expected to be completed in the first year of the second funding period. To overcome the challenges of evaluating large data sets, an extension of the Laue evaluation routines is planned at the beginning of the second funding period. Subsequently, the remaining data of the non-transparent grain boundary that cannot be evaluated to date should be analyzed and published.The main topic of the second funding period deals with the fatigue behavior of grain boundaries transparent to dislocation motion. Two types of grain boundaries will be investigated: transparent grain boundaries without a predefined transmission path and transparent grain boundaries with a predefined transmission path. The goal of the second funding period is a comprehensive understanding of dislocation structure formation and the initial stages of fatigue crack initiation near copper grain boundaries during cyclic loading.

在疲劳过程中形成的特征位错结构的内在和外在的尺寸效应的影响还没有详细研究，更不用说理解。特别是，由于缺乏合适的原位表征技术，迄今为止还无法详细研究单个晶界附近位错结构的形成及其在裂纹萌生中的作用。在XMicroFatigue项目的第一个资助期内，建立了一台“差分孔径X射线显微镜”（DAXM），它提供了对位错密度的非破坏性访问，弹性应变场和亚微米分辨率的取向，同时允许微物体的变形。双晶微弯曲悬臂梁-其中每一个都有一个单一的晶界在样品的中心-进行了循环加载和由此产生的位错结构进行了研究。选择铜作为模型材料。我们的重点是对位错滑移转移不透明的晶界。第一个资助期关于原位DAXM的建造和验证的所有目标都已成功实现。显微镜以及评估例程可供劳厄用户社区使用。关于对位错运动不透明的晶界疲劳问题，所有必要的实验都已成功完成，但对大型数据集的评价仍在进行中，预计将在第二个供资期的第一年完成。为了克服评价大型数据集的挑战，计划在第二个供资期开始时延长劳厄评价程序。随后，对迄今为止无法评估的非透明晶界的剩余数据进行分析并发表。第二个资助期的主要课题是对位错运动透明的晶界的疲劳行为。研究对象包括两种类型的晶界：无预定传输路径的透明晶界和有预定传输路径的透明晶界。第二个资助期的目标是全面了解位错结构的形成和循环加载过程中铜晶界附近疲劳裂纹萌生的初始阶段。