In situ diffraction analysis using high energy synchrotron radiation to investigate the influence of active deformation and recrystallisation mechanisms on the microstructural development of new magnesium sheet alloys

轧制过程中组织和织构的形成决定了镁合金板材的性能及其轻量化应用的技术潜力。弱化织构或改变主要织构成分以及细化晶粒，可明显提高板材的成形性。然而，这种纹理会导致机械各向异性增强。关于它们对微观结构和织构发展的影响，目前讨论了许多单独的机制。虽然分析揭示了轧制过程中不同变形机制的激活变化以及对再结晶行为的影响，但在三元镁合金中添加稀土元素或钙对这些机制的影响以及对组织和织构发展的影响尚不清楚。该项目的目的是利用同步辐射进行现场硬X射线衍射实验，以得出关于变形和再结晶机制对镁合金板材变形过程中组织和织构演变的影响的直接结论。同步加速器束上的原位测量方法能够在恒定的样品体积内以时间分辨的方式描述热机械处理过程中的缺陷和织构的发展，为分析微观结构变化的机理提供了良好的实验基础。在这一方法的同时，使用电子显微镜，例如扫描电子显微镜-EBSD和电子显微镜，在颗粒尺度(微米或纳米尺度)上检查微观机制。用综合方法研究了合金元素，特别是稀土元素或类似作用元素以及热机械处理对变形机制激活和再结晶的影响。了解单一机制及其对由此产生的微观结构、织构发展和力学性能的竞争贡献，可以得出这些机制的相对意义。此外，该结果允许基于金属物理的控制在镁薄板轧制过程中的织构发展。

The formation of microstructure and texture during a rolling process determines the properties of magnesium sheets and their technical potential for lightweight application. Weakening the texture or changing the main texture components as well as grain refinement, result in distinctly increased formability of the sheets. However, such textures lead to enhanced mechanical anisotropy. A high number of individual mechanisms is currently discussed regarding their impact on the microstructure and texture development. Although the analysis reveals altered activation of different deformation mechanisms as well as effects on the recrystallization behaviour during the rolling process, the effect of added rare earth elements or calcium in ternary magnesium alloys on these mechanisms as well as the impact on the microstructure and texture development is not well understood. The aim of this project is to apply in-situ hard X-rays diffraction experiments using synchrotron radiation in order to draw direct conclusions about the influence of individual deformation and recrystallisation mechanisms on the microstructure and texture evolution during deformation of magnesium sheet alloys. The in-situ measurement method at the synchrotron beam allows a time-resolved description of the defect and texture development in a constant sample volume during well-defined thermo-mechanical treatments, which offers an excellent experimental basis for the analysis of the mechanisms of the microstructure changes. Concurrent to this approach micro-mechanisms are examined on a grain scale (micrometre or nanometre scale) using electron microscopy, e.g. SEM-EBSD and TEM. The influence of alloying elements, particularly rare earth elements or similar-acting elements as well as the effect of a thermo-mechanical treatment on the activation of deformation mechanisms and recrystallisation is examined in a combined approach. Understanding single mechanisms and their competitive contribution on the resulting microstructure, texture development and mechanical properties allows the relative significance of such mechanisms to be derived. Furthermore, the results allow a metal physical based control of the texture development during rolling of magnesium sheets.