主持人：韩平畴 教授
时 间：2010.10.14 下午15:00
地 点： 廖凯原楼 2 号楼四层前沿交叉学科研究院会议室
Abstract
In the field of microscopy fundamental and practical reasons still remain that hamper a straightforward correlation between microscopic structural information and physical properties in nano-sized materials. We argue that one should focus in particular on in-situ rather than on postmortem observations of the microstructure.
In this presentation several examples will be presented to exemplify this viewpoint. First, we will show the excitements of the nanocluster deposition by starting with the basic building block of Fe, Nb, Mo and Co, i.e. the structure and properties of a single cluster studied with high-resolution transmission electron microscopy, followed by an in-situ TEM study of the coalescence and diffusion of clusters (sizes ranging between 3 nm and 10 nm) leading to the growth of nano-structured metal films. Next, in situ TEM nanoindentation and in-situ straining studies are discussed on crystalline and non-crystalline metallic materials. In-situ TEM displacement-controlled indentations in crystalline alloys show that many dislocations are nucleated prior to the initial macroscopic yield point and that the macroscopic yield event is associated with the rearrangements of the dislocations. In situ TEM straining and compression of amorphous metals permit an evaluation of the thickness of the liquid-like layer formed due to heat evolution after shear band development. An intriguing question is why and how nucleation and propagation of these shear bands are affected by the size of the system, and would it be possible to suppress brittleness and enhance ductility just by changing the size of the samples?
It is concluded that recent advances in in-situ microscopy can provide new insights about the nucleation and propagation of shear bends, dislocations and cracks in nano-sized metallic systems.
About the speaker
After his PhD in applied physics of the University of Groningen and his postdoctoral years in USA, Northwestern University and UC-Berkeley, Dr. Hossen was appointed as professor in applied physics by the Crown, ‘Koninklijk Besluit 101’ 6th October, 1977 at the University of Groningen. He is member of the “The Royal Holland Society of Sciences and Humanities”, of the “Royal Netherlands Academy of Arts and Sciences” (KNAW) division physics and vice -chairman of the council Physics and Astronomy of the KNAW. In 2002 he was elected Fellow of the American Society for Metals (FASM), followed by the Acta Materialia Inc award in 2003. In 2004 he became Fellow of the Wessex Institute of Great Britain. In 2005 he received the Eminent Scientist Medal of Wessex Institute of Great Britain/University of Southampton and the European Materials Gold Medal of the Federation of European Materials Societies (FEMS). In 2010, he received TMS-Triple M (Materials Metals Minerals) Society USA Fellow Award and Lee Hsun Lecture Award, Chinese Academy of Sciences, Institute of Metals Research.
Prof. Hosson published more than 800 publications in international scientific journals + conference proceedings, a/o. about 25 elaborate review papers and chapters in books on dislocation dynamics, transmission electron microscopy, and surface science/ engineering. Up to now he supervised 65 PhD theses and 306 Master Theses. He served as the editorial board of many international journals, and he is now the editor of Scripta Materialia/Acta Materialia, J. Nanoscience and Nanotechnology, and Journal of the Mechanical Behavior of Materials.
