Solid-state transformations involving quasicrystals

Solid-state transformations involving quasicrystals were studied in several aluminium-base ternary alloys. An ordering transformation of the icosahedral phase at room temperature was noticed. A transformation from higher symmetry of quasicrystals results in several orientational variants of the product phase, the total symmetry of which is the same as that of the parent phase. Six variants of the decagonal phase are produced on transformation from the icosahedral phase. The transformation of quasicrystalline phases to crystals involves the production of a high density of planar faults which produce streaking of reciprocal spots. The quasicrystals may transform into several intermediate metastable phases before transforming into the stable crystalline phase. Transformation from the decagonal quasicrystal usually involves two related crystalline phases.