Influence of grown-in voids on the structure of cleaved icosahedral Al-Pd-Mn quasicrystal surfaces

We investigated the changes in structure induced by heat treatment of cleav ed fivefold icosahedral Al-Pd-Mn quasicrystal surfaces close to, and far aw ay from, grown-in voids. Areas far away from grown-in voids exhibit a rough ening connected above 620 K with a decrease of the Al concentration, and ab ove 820 K a recovery of the surface composition. No change of the surface s tructure can be detected close to grown-in voids in the same temperature ra nge. The results indicate that the surface structure is influenced by the p resence of vacancies in the quasicrystals and that vacancies enhance the su rface roughening during heat treatment. (C) 2000 Elsevier Science B.V. All rights reserved.