Metastable formation of decagonal quasicrystals during solidification of undercooled Al-Ni melts: In situ observations by synchrotron radiation

Time-resolved in situ measurements using a combination of the electromagnetic levitation technique and energy dispersive diffraction of synchrotron radiation have been applied to the solidification of undercooled Al-Ni melts with 18-31.5 at.% Ni. Undercooling below the liquidus temperature did not alter the primary phase selection. However, during further cooling of semisolid samples the formation of a metastable decagonal quasicrystalline phase was observed, depending on the processing conditions. This metastable phase subsequently transforms and can only be retained at room temperatures when cooling with sufficient rates. Copyright (c) EPLA, 2009