Preferential sputtering of atoms and dimers from ordered and disordered Cu3Au

Using molecular-dynamics computer simulation, we investigate the sputtering of the ordered and disordered phase of Cu3Au by 1 keV Ar ions, as well as some related alloys. The sputter yield of the disordered alloy exhibits a strong preferentiality, which can be shown to be mainly due to the different mass of Au and Cu atoms, rather than to their different bonding. In contrast to expectation, the sputter preferentiality changes strongly with the alloy composition, and also with the local order in the alloy. The number and composition of sputtered dimers can be understood quantitatively from a statistical combination model, if the total sputter preferentiality and the correlations existing in the emission statistics are taken duly into account; the different short-range order in ordered and disordered Cu3Au has no further statistically significant effect on the dimer emission. (C) 1999 Elsevier Science B.V. All rights reserved.