Seminars

MAIN DEPARTMENT SERIES
Host: William W. Gerberich (CEMS)
DONALDSON LECTURE SERIES
Joint seminar with Departments of Chemistry, Chemical Engineering and Materials Science, and Mechanical Engineering

LECTURE 1 Constrained Plasticity and Fatigue in Sub-micron Metallic Films Thursday, March 10, 2005 11:15 a.m. Location: B75 Amundson Hall

LECTURE 2 From Biological To Artificial Nano-Scale Devices: How Flies And Geckos Adhere To Surfaces Friday, March 11, 2005 Time: 4:00 p.m. Location: 100 Smith Hall A reception will follow in the Dale Shephard Room of the Campus Club

by

Eduard Arzt
Max Planck Institute for Metals Research and
Institute of Physical Metallurgy
University of Stuttgart
Stuttgart, Germany

Abstract: Mechanical properties depend strongly on size; while this principle has long been exploited in the microstructural design of materials, it is nowadays possible to structure materials in the form of films with thicknesses down to nanometer dimensions. A question of both fundamental and practical importance is how the mechanisms of deformation scale with size and what the limiting strength values are. Research over recent years has shown that below the “sound barrier” of about one micrometer film thickness the plastic behavior, fatigue resistance and other properties are dramatically modified. This is due to the interaction of lattice defects with the boundaries and interfaces in non-scale materials. Also, the substrate constraint can give rise to new deformation mechanisms, such as dislocation glide on unexpected planes (termed “parallel glide”). In this presentation, an overview of our recent results on fcc metals will be given. Particular emphasis will be placed on in-situ transmission electron microscopy and a newly developed synchrotron technique for measuring stress-strain cures of ultra-thin films.

Bio: — Eduard Arzt holds a joint appointment since 1990 as Director at the Max Planck Institute for Metals Research and Professor of Physical Metallurgy/Metal Physics at the University of Stuttgart, Germany. He received a Ph.D. in physics from the University of Vienna, Austria, in 1980, for a thesis produced at the University of Leoben in powder-metallurgy. After his post-doc years (1981/82) at the Engineering Department of the University of Cambridge, UK, with Michael F. Ashby he initiated a program on high-temperature strength at the Max Planck Institute for Metals Research, with special emphasis on dispersion-strengthened superalloys for use at extremely high homologous temperatures. In cooperation with German industry, these basic concepts have led to improved high-temperature alloys, which have made their way into mass production e.g. in the automotive industry. A year as a Visiting Researcher at Stanford University motivated him and his group to switch his field to mechanical and electrical properties of thin films. These studies have led to a more consistent picture of mechanical and microstructural aspects in electromigration and have uncovered strong effects of film thickness on yield strength. His group was the first worldwide to tackle the question of fatigue in small dimensions with several new testing techniques - studies that are now branching out to help in the development of new reliable filter systems for cellular telephones.

His most recent adventure has led him into close collaborations with biologists, botanists and biophysicists with whom he applies the micro- and nanomechanical know-how in his group to biological systems. Emphasis is placed on the mechanics of living cells and on the correlation between structure and performance of attachment devices in insects (flies, beetles), spiders, and geckos. In his group, it has recently been possible for the first time to measure the adhesion of single gecko hairs (spatulae), with dimensions of 200 nm, to selected substrates by atomic force microscopy. Besides developing an appreciation for the aesthetic and efficient design of living mechanical systems, the aim of this work is to extract principles from nature which can be used to optimize technical devices.

Eduard Arzt has published more than 260 papers and co-authored several patents. He is a regular reviewer for German and international research projects, and is on the board of several research institutions and industrial award committees. He is co-editor of one of the highest-impact journals, Progress in Materials Science, and also a member of the editorial boards of the MRS Bulletin, Materials Science and Technology, Advanced Engineering Materials, and Zeitschrift f¸r Metallkunde. His awards include the Acta Metallurgica Outstanding Paper Award, the Max-Planck Research Award (together with W.D. Nix, Stanford), and the highest German science award, the Gottfried Wilhelm Leibniz Prize. He is a corresponding member of the Austrian Academy of Sciences and a member of the German Science Academy Leopoldina. He maintains strong links with US institutions, among them Stanford University, University of California at Santa Barbara and Massachusetts Institute of Technology, where he regularly spends periods of time.