Initial crystallization processes of Hf-Cu-M (M=Pd, Pt or Ag) amorphous alloys

Hf70Cu30, Hf70Cu20Pd10, Hf70Cu20Pt10, Hf70Cu20Ag10, Hf73Pd27 and Hf73Pt27 a morphous alloys were prepared by a single roller melt-spinning method and t he crystallization process was studied by differential scanning calorimetry (DSC), X-ray diffraction and transmission electron microscopy. A single ex othermic peak was observed in the DSC curves of Hf70Cu30, Hf70Cu20Ag10 and Hf73Pt27 amorphous alloys, which corresponds to the precipitation of stable crystalline phases. Multiple exothermic peaks were observed in the DSC cur ves of Hf70Cu20Pd10, Hf70Cu20Pt10 and Kf(73)Pd(27) alloys, of which the low -temperature one corresponds to the precipitation of nanoscale icosahedral quasicrystalline phase (I-phase). The I-phase is in a metastable state sinc e further annealing leads its transformation to other stable crystals. The relation among the atomic configurations of the amorphous alloy, I-phase an d stable crystalline phases is discussed. (C) 2001 Acta Materialia Inc. Pub lished by Elsevier Science Ltd. All rights reserved.