Bonding characteristics and strengthening of CuZr fundamental clusters upon small Al additions from density functional theory calculations

We report on density functional theory results referring to the bonding characteristics and the strengthening induced by small Al additions in representative icosahedral Cu7Zr6 and rhombic dodecahedral Cu9Zr6 clusters and their interconnections. We found that the presence of Al modifies seriously the interactions with its surroundings, introducing strong covalent-like bonding that may resist strain, thus explaining experimental observations referring to the strengthening effect of metallic glasses upon small Al additions. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.