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 cleaved fivefold icosahedral Al–Pd–Mn quasicrystal surfaces close to, and far away from, grown-in voids. Areas far away from grown-in voids exhibit a roughening connected above 620 K with a decrease of the Al concentration, and above 820 K a recovery of the surface composition. No change of the surface structure can be detected close to grown-in voids in the same temperature range. The results indicate that the surface structure is influenced by the presence of vacancies in the quasicrystals and that vacancies enhance the surface roughening during heat treatment.