报告题目(中文)：调制马氏体的孪晶结构:关于原子层移动的分析

报告题目(英文)：Twin structure in modulated martensites: an analysis including shuffling of atomic layers

报告内容简介：The trained and self-accommodated martensite microstructures of 10M Ni-Mn-Ga single crystals were studied by back scattered electron imaging and electron backscatter diffraction in a scanning electron microscope. These data were then compared with theoretical calculations using a long periodic commensurate modulated monoclinic lattice and Gautam and Howe (G-H) model in order to establish twin boundary (TB) hierarchy according to their surface energy. The whole spectrum of TBs including type I, type II, and compound twins were detected and theoretically predicted. Using the G-H model and long periodic structure along with a small displacement of atoms connected with lattice modulation allowed to calculate all twin elements including their surface energy. These data are then confronted with theoretical predictions of classical continuum mechanics and minimum shear approaches, which disregard the lattice modulation. As it is shown including the modulation modifies the twin systems (twinning plane and twinning direction) for some TBs. Moreover, it strongly affects the interfacial energy which allows to rank TBs in 10M Ni-Mn-Ga system. Large differences in surface energy between different TBs are associated with atomic interface configurations and de-shuffling of atoms to form a coherent twin plane. Therefore, unlike the classical geometrical concepts, the G-H model allows to perform not only a quantitative but also qualitative analysis of all possible twin boundaries. As a result of new approach, a model that involves interfacial energy, shuffling of atoms and homogenous shear type deformation for TB determination is presented. In addition, irrational or step-like planes not only for type II but also for type I twin boundaries is predicted. Furthermore, a description of twin formation with respect to two different reference systems is completed, i.e. parent-based and monoclinic ones. In this way, a hierarchical twin microstructure of 10M martensite is established.

报告人姓名：Robert Chulist

报告人简介(中文)：波兰科学院冶金与材料科学研究所教授，主要研究领域是包含马氏体相变的智能金属材料，以及形状记忆效应、磁热效应、超弹性和伪弹性等相关效应。目前，研究兴趣在于金属、合金和金属间相受到大塑性变形(SPD)或爆炸焊接加工时，其显微组织、机械性能和织构的研究。

报告人简介(英文)：My primary research area is the study of smart metallic materials exhibiting a martensitic transformation and related effects such as shape memory effect, magnetocaloric effect and super and pseudoelasticity. Concurrently, my research interests lie in the area of microstructural, mechanical and texture examination of metals, alloys and intermetallic phases subjected to sever plastic deformation (SPD) or explosive welding process.

报告人单位(中文)：波兰科学院冶金与材料科学研究所

报告人单位(英文)：Institute of Metallurgy and Materials Sciences of the Polish Academy of Sciences

报告时间：2019-11-25 10:00

报告地点：日新楼506

主办单位：各大菠菜网入口

联系人：李喜

联系方式：13764420935