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美国密歇根州立大学Martin A. Crimp教授讲学通知

发布时间:2017-06-14被阅次数:14来源:材料学院

应我校材料科学与工程学院黄永江副教授邀请,美国密歇根州立大学化学工程与材料科学系Martin A. Crimp教授近日来我校访问并进行学术讲座欢迎感兴趣的老师同学参加。如果有留学密歇根州立大学的同学也可以现场交流。

  

报告一

题目:Introduction of Michigan State University

时间:2017616日上午9:00

地点:材料学院322

  

报告二

题目:The Role of Grain Boundaries in the Heterogeneous Deformation in Titanium and Titanium Alloys: Comparisons between Experimentally Characterized and Modeled Behavior

时间:2017616日上午9:30

地点:材料学院322

摘要

The anisotropic deformation behavior of commercially pure Ti (CP-Ti) and Ti-5Al-2.5Sn has been investigated using tension and bending at ambient and elevated temperature, as well as using nanoindentation techniques. Microstructures were characterized using SEM and EBSD (electron backscattered diffraction) mapping prior to, during, and after deformation.  SEM/EBSD based trace analysis has been used identify the active deformation systems as a function of local grain environment. Further analysis has been carried out using atomic force microscopy (AFM) to quantify the local plastic deformation through slip step height analysis, as well as to characterize the nature of indentation pile-ups and the effect of grain boundaries on these pile-ups.  Selected areas have been examined using 3-D x-ray diffraction to characterize sub surface grain structure and crystal rotations. To complement these experimental studies, a number of different crystal plasticity finite element (CPFE) simulations have been carried out.  Both quasi and full 3-D finite element meshes that replicate experimentally characterized polycrystalline grain arrays have been computationally deformed.  These simulations accurately reproduce significant aspects of the experimental studies, including some crystal rotations and surface topography development.  Nevertheless, the simulations fail to accurately predict all of the details of the experimentally characterized deformation, indicating that further work to include grain boundary behavior in the simulations is needed.  Comparison of experimentally measured pile-ups with CPFEM simulations of indentation piles-ups is shown to be an effective tool to assess the nature of dislocation slip transfer in a local bi-crystal environment.

  

报告三

题目:Electron Channeling Techniques for Orientation Analysis and Defect Imaging in the Scanning Electron Microscope

时间:2017616日上午10:30

地点:材料学院322

摘要  

Historically, the relationships between microstructural features and the local crystallography of materials has been characterized using transmission electron microscopy (TEM), which not only allows diffraction studies based on selected area electron diffraction (SAED) and convergent beam electron diffraction (CBED), but also imaging and defect analysis based on diffraction contrast.  Unfortunately, TEM is often limited by the preparation and use of the requisite thin foils.   Scanning electron microscopy (SEM) approaches for linking the morphology and crystallography of materials have only more recently been developed.  These approaches offer the ability to carry out a number of different types of electron channeling/diffraction studies, but eliminate the need for thin foil specimens.  Selected area channeling patterns (SACPs) and electron back scattered diffraction (EBSD) patterns can be used to measure crystalline orientations at spatial resolutions in the sub-micron range, with recent developments allowing highly precise angular measurement and defect structure characterization through cross-correlation approaches.  Direct imaging of nanoscale defects, such as dislocations and deformation twins, in bulk crystals can be carried out using electron channeling contrast imaging (ECCI), with defect characterization accomplished using approaches analogous to diffraction contrast analysis used in TEM.  This talk will cover the basic processes of electron diffraction and channeling phenomena in bulk samples using SEM, along with the experimental parameters involved with carrying out electron diffraction/channeling analyses.  Examples of the capabilities of these integrated studies will be presented, including the imaging of dislocations under a variety of conditions, characterization of sub-boundary structures, mapping of dislocation density distributions, and grain boundary deformation transfer.  

  

报告人简介:

Martin A. Crimp教授现为美国密歇根州立大学教授,是国际享有盛誉的电子显微技术专家。曾担任美国TMS物理冶金学会主席,TMS教育委员会主席,曾先后在牛津大学、凯斯西储大学、密歇根技术大学工作。在国际期刊和高水平学术会议上发表论文200余篇培养博士、硕士研究生50余人现为美国40余大型企业的高级顾问International Journal of Plasticity等十余种国际著名期刊的编委会委员,曾在国际学术期刊组织20余次专刊,在材料学界以及电镜界有较大的国际影响力。Martin A. Crimp教授曾多次和我校开展合作,曾是我校的客座教授,为我校和密西根州立大学之间的国际交流做了很多贡献。

  

材料科学与工程学院

2017614


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