Metastable transformation states of decagonal Al-Co-Ni due to inhibited decomposition - art. no. 134208

The transformation behavior of high-Co decagonal AI-Co-Ni is studied. Start ing from stability considerations based on a number of annealing treatments we check theoretical predictions of the stabilization mechanism and transf ormation mechanism by phason strain analysis and tiling analysis. The quasi crystal transforms in the first stages into nanodomain structures and final ly decomposes into a quasicrystal and a normal crystalline phase. Before de composition, the material is locked in a disordered state exceeding the per iodic order allowed for a one-dimensional quasicrystal. This is interpreted as the maximum periodic order achievable without diffusion. From consideri ng different reasons for phason strain we conclude that disorder in tilings related to phase transformations can wrongly be associated with that sugge sted by the random tiling hypothesis.