Undercooling and solidification behaviour of a metastable decagonal quasicrystalline phase and crystalline phases in Al-Co

The maximum undercoolability of Al-Co melts of 72 and 74 at.% Al was studied by electromagnetic levitation technique. A metastable decagonal phase was solidified in largely undercooled samples of Al74Co226. The melting temperature of the metastable decagonal phase was determined to be 1440 K. To identify the phases crystallized upon undercooling the melt, the as-solidified samples were analyzed with respect to their phase-structures by means of scanning and transmission electron microscopy (SEM, TEM) and X-ray diffraction (XRD), Differential thermal analysis (DTA) was employed to measure the heat of fusion δHf of the metastable D-phase.