Experimental analysis of the orientation dependence of deformation laminates.

该项目的目的是对金属中局部形变诱导的晶体取向图案化进行实验研究，并将观察到的微观结构与理论模型进行定量比较。在之前的资助期间，我们在层合理论和实验相结合方面取得了重大进展。我们用定向显微镜EBSD(电子背散射衍射)观察到的剪切变形铜单晶体中的取向图样与运动相容的层合板模型进行了定量的关联，该技术是在这一研究计划中发展起来的。将实验观察到的图案化现象描述为层合板，预测其形成是基于强烈的潜在硬化，这在显微镜和微塑性研究领域是新的。然而，该模型为能量有利的层板变化提供的“能量景观”还没有被探索。因此，对于申请资助期，我们建议对图案化现象的取向相空间进行实验研究，并与层叠模型(P6，Dondl/M？uller)相关联。对铜和B2有序NiAl单晶进行了受控无摩擦均匀加载的剪切实验。这两种材料都将在几个方向上塑性变形，以便研究单滑移、双滑移和三滑移活动。在B2有序NiAl的情况下，少量的势滑移系统允许精确地激活滑移系统，并应导致更明显的取向图样。此外，还将与P6合作进行弯曲实验中提供的自由表面边界条件的优化组织研究。动态过程的研究，如分层的初始步骤和随后的组织演变，是微塑性中特别感兴趣的问题。为了研究微结构动力学，我们将对层状微结构的演化进行实验，并伴随着时间连续的有限晶体塑性计算(P3，Hackl/Kochmann/Wagner)。探讨了层板形成的能量原因和形成和演化的机制。此外，还将进行有关二阶层板的形成和演化的实验以及对这些结构的结晶学分析。这一研究将为高阶层合板(P3)有限塑性模型的进一步发展提供支持。除了研究层状结构的进展外，我们还将研究层状微结构中位错结构的演变。这些研究为位错捕获和位错壁的产生提供了与层板形成相关的机制。为此，我们将采用电子沟道对比技术，它允许观察位错结构，并利用EBSD同时分析周围的微结构。因此，我们可以探索位错后排列对层状组织形成的影响。这样，我们就可以回答层合理论中存在的一个悬而未决的问题，例如细胞结构是否可以理解为单滑移区的相容排列。

The aim of the project is the experimental investigation of the local deformation-induced patterning of the crystallographic orientation in metals and the quantitative comparison of the observed microstructures with theoretical models. In the previous funding period, we made significant progress in uniting lamination theory and experiments. We quanti- tatively correlated the orientation patterning observed in shear deformed copper single crystals using orientation microscopy EBSD (electron back scatter diffraction) with a model of kinematically compatible laminates using a technique developed within this re- search initiative. The specification of the experimentally observed patterning phenomenon as a laminate the formation of which is predicted to be based on strong latent hardening is novel in the research fields of microscopy and microplasticity. However, the ”energy landscape” provided by the model for energetic favorable laminate variations is not yet explored. Therefore, for the applied funding period, we propose the experimental in- vestigation of the orientation phase space of patterning phenomena supported by the correlation to the lamination model (P6, Dondl/M¨uller). Shear experiments for well con- trolled frictionless homogeneous loading will be performed on single crystals of copper and B2 ordered NiAl. Both materials will be plastically deformed in several orientations so that single, double, and triple slip activity can be studied. A small number of poten- tial slip systems in case of B2 ordered NiAl allows precise activation of the slip systems and should lead to more pronounced orientation patterning. Furthermore, study on opti- mal microstructures to free surface boundary conditions provided in bending experiments will be performed in cooperation with P6. Study of the dynamic processes such as the initial steps of lamination and subsequent microstructure evolution are of particular in- terest within the microplasticity. To study the microstructure dynamics, we will perform experiments on the evolution of laminated microstructures which will be accompanied by time-continuous finite crystal plasticity calculations (P3, Hackl/Kochmann/Wagner). The energetic reasons and the mechanisms for the initiation and evolution of the laminate formation will be explored. Moreover, experiments regarding formation and evolution of rank-two laminates and crystallographic analysis of these structures will be performed. This investigations will be supported by further development of the finite plasticity model for high-order laminates (P3). Beside the study of the progress of the lamination, we will investigate the evolution of the dislocation structures within the laminated microstruc- ture. These investigations provide insights into the mechanisms of dislocation trapping and generation of dislocation walls in correlation with the laminate formation. For this reason, we will apply the electron channeling contrasts technique which allows the ob- servation of the dislocation structures and the simultaneous analysis of the surrounding microstructure by using EBSD. Thus, we can explore the impact of the dislocation rear- rangements on the formation of laminated microstructure. This way, we can answer one of the open questions existing in lamination theory, such as whether cell structures may be understood as compatible arrangements of regions of single slip.