TMS 2007: Lectures

Institute of Metals/Robert Franklin Mehl Lecture

Topic: "Inverse Nanostructuration in Complex Metallic Alloys"
Date: Monday, Feb. 26

Now that new tools are available to solve the crystallographic structure of complex compounds in metallic alloy systems, a vivid interest manifests itself to discover new compounds in multiconstituent alloys. Several are yet known to contain hundreds or more atoms per unit cell.

In the meantime, real efforts are made for better understanding of the properties of these compounds and the mechanisms that underpin the progressive loss of metallic character when the size of the unit cell increases.

This lecture will focus on a few examples of atypical behavior of complex metallic alloys, including quasicrystals as the ultimate state of structural complexity in a crystal made of metals. Examples are transport properties, surface electronic structure, surface energy, wetting and friction. All examples show the same trend, namely apparent localization of electronic states, loss of conductivity, opening of gaps, softening with no work hardening, etc.

SPEAKER

JEAN-MARIE DUBOIS Director Institut Jean Lamour

All phenomena are reminiscent of what is observed in nanostructured metals but together with the increase of the size of the unit cell. This effect is coined “inverse nanostructuration” by the lecturer who will argue that complex metallic alloys help us revisit ancient problems in metal physics, while in parallel potential applications may be sorted out.

Jean-Marie Dubois is Distinguished Director of Research at CNRS, France; his research topics have revolved around metal physics and engineering of complex materials. He is also the director of Institut Jean Lamour, a joint CNRS-Nancy University institute and is coordinating the CMA European Network of Excellence.

This network is dedicated to research on complex metallic alloys and comprises 19 partner institutions in 12 European countries. After establishing structure models for metallic glasses and quasicrystals, Dr. Dubois became interested in applied properties of these materials: heat insulation, low adhesive properties and infrared light absorption.

He is currently working on cold-welding and solid-solid adhesion in vacuum of complex intermetallics against steel and more generally on understanding the surface energy of those materials.