Decagonal quasicrystals with different periodicities along the tenfold axis in rapidly solidified Al─Ni alloys

Abstract

A decagonal quasicrystal with a periodicity of 1·6 nm along the tenfold axis, similar to that in Al─Pd and Al─Co, has been found in a rapidly solidified Al₆Ni alloy containing a few per cent of silicon. In addition, a new decagonal phase has been found in Al₄Ni which has a periodicity of 0·4 nm along the tenfold axis. This decagonal phase is different from those reported before in the aluminium–transition metal alloys. A new metastable crystalline phase Al₉Ni₂ having the structure of Al₉Co₂ has been found.