In-Situ Defect Spectroscopy of Al Welds During Mechanical Load Using a Scanning Positron Microbeam

使用扫描正电子微束对机械负载过程中的铝焊缝进行原位缺陷光谱分析

• 批准号: 461170118
• 负责人: Professor Dr. Christoph Hugenschmidt
• 金额: --
• 依托单位: Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II)
• 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/461170118?language=en
• 关键词: Situ; Defect; Spectroscopy; Al; Welds

The goal of our project is to contribute to the fundamental understanding of the relation between material defects created on an atomic level and the mechanical stability of welds. For this purpose, we want to investigate in-situ the formation and distribution of defects in laser beam welds and friction stir welds of Al alloys during mechanical load. In particular, age-hardenable alloys – we will focus on AlCu6Mn – play an important role in aerospace industry due to their high tensile strength, excellent corrosion resistance and good weldability. During welding the large heat impact with subsequent rapid cooling results in a complicated interplay of vacancy formation, dissolution of precipitates, and partial defect annealing. This in turn results in a complex microstructure with a local variation of the concentration of vacancies, precipitates and grain refinement. The associated local variation of the strength is crucial for the mechanical resilience and the lifetime of the welded technical component. Spatially resolved positron beam experiments (spatial resolution ~30µm) will be applied because they are especially suited for the non-destructive exploration of lattice defects and their elemental environment in technical alloys. For our experiments, we will use the unique scanning positron-microbeam at the CDB spectrometer at the high-intensity positron source NEPOMUC. In-situ defect spectroscopy of the Al specimens will be performed during tensile and fatigue tests starting at room temperature up to high temperature. We will also apply complementary techniques, e.g. optical microscopy of the micro-sections and measurements of the micro-Vickers hardness By this, we will be able to correlate the formation and distribution of defects such as vacancies, vacancy-solute atom complexes, and precipitates with macroscopic properties like tensile strength and hardness. We expect that the outcome of this project will have a large impact for technical applications not only for welded Al alloys but for metallic alloys general. In the long term, we want to establish spatial resolved positron annihilation spectroscopy as a powerful tool for defect analysis that is of high importance in engineering science for the application of technical materials and components, e.g., in shipbuilding, airplane and automotive industry.

我们项目的目标是促进对原子水平上产生的材料缺陷与焊接机械稳定性之间关系的基本理解。为此，我们对铝合金激光焊接和搅拌摩擦焊接在机械载荷作用下缺陷的形成和分布进行了现场研究。特别是时效硬化合金，我们将重点关注AlCu6Mn，由于其高抗拉强度，优异的耐腐蚀性和良好的可焊性，在航空航天工业中发挥着重要作用。在焊接过程中，巨大的热冲击和随后的快速冷却导致空位形成、析出相溶解和部分缺陷退火的复杂相互作用。这反过来又导致了一个复杂的微观结构与局部变化的空位，沉淀和晶粒细化的浓度。相关的局部强度变化对焊接技术部件的机械回弹性和寿命至关重要。空间分辨正电子束实验（空间分辨~30µm）将被应用，因为它们特别适合于对技术合金中晶格缺陷及其元素环境的非破坏性探测。在实验中，我们将在高强度正电子源NEPOMUC的CDB光谱仪上使用独特的扫描正电子微束。铝试样的原位缺陷光谱将在拉伸和疲劳试验期间进行，从室温到高温。我们还将应用互补技术，例如显微切片的光学显微镜和显微维氏硬度的测量。通过这种方法，我们将能够将空位、空位-溶质原子络合物和析出物等缺陷的形成和分布与抗拉强度和硬度等宏观性能联系起来。我们预计，该项目的成果将不仅对焊接铝合金的技术应用，而且对一般金属合金的技术应用产生重大影响。从长远来看，我们希望建立空间分辨正电子湮灭光谱作为缺陷分析的强大工具，在工程科学中对技术材料和部件的应用具有重要意义，例如造船，飞机和汽车工业。