Stable Al-Cu-Co decagonal quasicrystals

Stable Al₆₅Cu₂₀Co₁₅ and Al₆₅Cu₁₅Co₂₀ decagonal quasicrystals, sometimes using a few percent of Si to replace Al, can be grown directly from the melt as single grain decaprisms of up to 1 cm in length. Some salient features of their solidification processes, growth morphologies, surface structures, high resolution electron microscopic images, two dimensional quasicrystalline structure, relationship to one-dimensional quasicrystals, crystalline approximants, and dislocations are presented.