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Characterization and modeling of the interplay between grain boundaries and heterogeneous plasticity in titanium

钛晶界与异质塑性之间相互作用的表征和建模

基本信息

批准号：
198771379
负责人：
Professor Dr. Franz Roters, since 5/2015
金额：
--
依托单位：
Max-Planck-Institut für Eisenforschung GmbH (MPIE)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/198771379?language=en
关键词：
Characterization modeling interplay between grain

项目摘要

The strengthening effect of grain boundaries is one of the key components in the development of modern structural materials. This is illustratcd by the intcrisificd research efforts 011 ultra fine grained materials, grain boundary engineering, and nanocrystalline materials over the last decade. The precise nature of the often beneficial effects of grain boundaries, however, have not been understood to a level which would allow for theory guided optimization of microstructures and accelerated alloy development.We propose to combine, improve, and apply recently developed approaches to investigate and quantify the micromechanical behavior of grain boundaries. We will achieve this using a recently developed technique that evaluates indentation topographies to generate a detailed understanding of plastic anisotropy of single crystals. A prominent advantage of the method is its efficiency in generating high quality data that previously could only be generated by careful single and bi-crystal experimentation, which both involve significantly higher amounts of experimental effort. By applying this indentation approach, combined with state of the art characterization and Simulation methods, we will develop a sound understanding of the interplay between grain boundaries and heterogeneous plasticity in titanium polycrystals for the first time.The goals of our research program are: (1) Carry out indentation within the interiors of large grains of a-titanium to effectively collect single crystal data coupled with extensive characterization of the resulting plastic defect fields surrounding the indents. By correlating with models of the indentation, we will arrive at a precise constitutive description of the anisotropic plasticity of single-crystalline titanium. (2) Extend this methodology to indentations close to grain-boundaries, i.e. quasi bi-crystal deformation. (3) Compare the measured characteristics of indentations at grain boundaries to simulated indentations äs predicted by the constitutive model calibrated using the single crystal indentations. This will lead us to qualitative understanding on how different types of grain boundaries modulate the local deformation patterns. (4) Based on this qualitative understanding we will implement a grain boundary transmissivity formulation into our non-local crystal plasticity formulation that fully accounts for all relevant influences from the crystallographic and geometric parameters that describe the boundary and the 3-dimensional relations between deformation Systems on both sides of the interface. (5) This grain boundary aware constitutive model will be validated against the collected indent characteristics. (6) Once the constitutive model has been developed, it will be further validated using data from previously collected high resolution experimental data from a polycrystalline microstructural patch deformed in a bulk specimen.Broad Impact: It is difficult to think of an aspect of material processing that affects society more than being able to reliably predict heterogeneous deformation, which is required before prediction of performance or reliability can be made with physically based confidence. This will be accomplished in a joint research project involving Michigan State University (MSU) and Max-Planck-Institut für Eisenforschung (MPIE) in Düsseldorf, Germany, where mutually useful skills are present which can reach the above goals when integrated into an international cooperative research program. The work will be carried out by 3 Ph.D. students under the guidance of Profs Bieler and Crimp at MSU, and a post-doc and one Ph.D. Student guided by Claudio Zambaldi, Dr. Philip Eisenlohr at MPIE. Extensive exchanges between the two laboratories will occur in order to integrate experimental and analytical methods to reach these goals.

晶界强化效应是现代结构材料发展的关键组成部分之一。近十年来在超细晶材料、晶界工程和纳米晶材料等方面的研究成果说明了这一点。然而，晶界的确切性质往往是有益的影响，还没有被理解到一个水平，这将允许理论指导优化的微观结构和加速合金development.We建议联合收割机，改进，并应用最近开发的方法来调查和量化的晶界的微观力学行为。我们将实现这一目标，使用最近开发的技术，评估压痕形貌，以产生一个详细的了解单晶的塑性各向异性。该方法的一个突出优点是它在生成高质量数据方面的效率，这些数据以前只能通过仔细的单晶和双晶实验来生成，这两者都涉及显著更高的实验工作量。通过应用这种压痕方法，结合最先进的表征和模拟方法，我们将首次对钛多晶体中晶界和非均匀塑性之间的相互作用有一个良好的理解。我们的研究计划的目标是：（1）在大颗粒的内部进行压痕-钛，以有效地收集单晶数据，并结合压痕周围的所得塑性缺陷场的广泛表征。通过与压痕模型相关联，我们将得到单晶钛各向异性塑性的精确本构描述。(2)将该方法扩展到接近晶界的压痕，即准双晶变形。(3)将晶界处压痕的测量特性与使用单晶压痕校准的本构模型预测的模拟压痕进行比较。这将引导我们定性地了解不同类型的晶界如何调节局部变形模式。(4)基于这种定性的理解，我们将实现一个晶界transmittance公式到我们的非局部晶体塑性公式，充分考虑所有相关的影响，从晶体学和几何参数，描述边界和三维之间的关系变形系统的界面两侧。(5)该晶界感知本构模型将针对所收集的晶界特征进行验证。(6)一旦本构模型被开发出来，它将被进一步验证使用的数据从以前收集的高分辨率实验数据从多晶微观结构补丁变形在一个散装标本。很难想象材料加工的一个方面比能够可靠地预测非均匀变形更能影响社会，这是在能够以基于物理的置信度进行性能或可靠性预测之前所需要的。这将在一个联合研究项目中完成，该项目涉及密歇根州立大学（MSU）和德国杜塞尔多夫的马克斯-普朗克研究所（MPIE），其中存在相互有用的技能，当融入国际合作研究计划时，可以达到上述目标。这项工作将由3名博士进行。学生的指导下教授Bieler和卷曲在密歇根州立大学，和一个博士后和一个博士。学生由Claudio Zambaldi，Philip Eisenlohr博士在MPIE指导。两个实验室之间将进行广泛交流，以整合实验和分析方法，实现这些目标。