Abstract
The transformation of the decagonal quasicrystalline phase in Al62Cu20Co15Si3 and Al65Cu15Co20 to a normal crystalline phase was studied by electron diffraction and high-resolution electron microscopy. The transformation was induced by electron irradiation at room temperature. In the first stage the decagonal phase transformed into a b.c.c. phase. After prolonged irradiation this phase ordered to a CsCl-type cubic phase.