The conference will focus at a few examples of the atypical behavior of complex metallic alloys, including quasicrystals as the ultimate state of structural complexity in a crystal made of metals. The main issue in this topic is to understand why Nature selects complex compounds, whereas most constituent metals embody simple versions of the densest possible packing of hard spheres.

In turn, complexity entails atypical physical properties that significantly depart from the ones known for simple metals and their alloys. Examples are transport properties, surface electronic structure, surface energy, wetting and friction.

The view of the author is that complex metallic alloys help us revisit ancient, and probably also well-established problems in metal physics, thus improving our understanding of the basic properties of condensed matter, while in parallel potential applications may be sorted out. Examples will be given.