Experimental characterization of micro plasticity and dislocation microstructure

在项目P7中，已经建立了单晶银微梁弯曲以及Au微丝拉伸和扭转测试的实验方法。在这两种加载情况下，样品已被测试到不同程度的塑性变形，以研究位错微观结构的具体演变。变形光束的表征主要通过EBSD完成，而线则通过使用同步辐射的劳厄微衍射进行检查。这两种方法都提供了局部取向差数据，这些数据又提供了有关位错结构的信息。因此，信息GND密度，它们的横向分布在一个给定的横截面，个别滑移系的影响，以及高达五个组件的奈张量已经获得。这些信息被详细分析并以特定的方式处理，可以直接与P1（Böhlke）的梯度晶体塑性模拟，P2（Sandfeld），P3（Gumbsch/Schulz）和P8（Hochrainer）的CDD模拟以及P5（Weygand）的DDD模拟进行比较。 到目前为止，实验方法主要集中在单晶样品或横截面的表征上。在第二个资助期内，该方法将应用于具有明确晶粒或相界的样品和微观结构，以研究这些界面处位错的相互作用和排列。因此，我们将对外延生长的Au或Ag寡晶、粗晶Au或Ag样品以及单晶镍基高温合金进行微观力学测试和表征。扩展到晶粒排列和相干相界的研究对应于研究组内基准系统的定义。

Within project P7 experimental methodologies for bending of single crystalline Ag microbeams as well as for tensile and torsion testing of Au microwires have been established. In both loading scenarios, the samples have been tested up to different degrees of plastic deformation to investigate the specific evolution of dislocation microstructure. The characterization of the deformed beams is mainly done by EBSD while the wires are examined by Laue microdiffraction using synchrotron radiation. Both methods have provided local misorientation data which in turn gave information about the dislocation structure. Thus, information about GND densities, their lateral distribution across a given cross-section, the influence of individual slip systems, as well as up to five components of the Nye tensor have been obtained. This information was analyzed in detail and processed in specific ways that it can directly be compared with Gradient Crystal Plasticity simulations of P1 (Böhlke), CDD simulations of the projects P2 (Sandfeld), P3 (Gumbsch/Schulz) and P8 (Hochrainer) as well as DDD simulations of P5 (Weygand). So far, the experimental methodologies have focused on the characterization of single crystalline samples or cross-sections. In the second funding period, the methodology will be applied to samples and microstructures with defined grain or phase boundaries in order to investigate the interaction and arrangement of dislocations at such interfaces. Therefore, we will implement micromechanical testing and characterization of epitaxially grown Au or Ag oligocrystals, coarse grained Au or Ag samples as well as single crystalline Ni base superalloys. The extension to the investigation of grain arrangements and coherent phase boundaries corresponds to the definition of the benchmark systems within the research group.