About the role of hybridization in wetting and friction on Al-based complex metallic compounds

The reversible adhesion energy of water was deduced for many Al-base conventional and complex intermetallics from contact angle measurements performed at the surface of the native oxide layer that always exists in air on top of such materials. Surprisingly, this quantity shows a direct correlation with the density of states at the Fermi level in the bulk material. Similarly, we obtained a straightforward assessment of the surface energy of Al-base complex intermetallics using pin-on-disk measurements performed in a vacuum chamber (using an adequate calibration procedure). For the two types of data, we stress in this article the important role played by the hybridization that occurs between Al p-d and transition metal (TM) d states in the bulk specimen, a mechanism that is also responsible for the specific stability of quasicrystals and high-rank approximants in Al(TM) systems. (c) 2006 Elsevier B.V. All rights reserved.