Initial crystallization processes of Hf–Cu–M (M=Pd, Pt or Ag) amorphous alloys Original Research Article

Hf70Cu30, Hf70Cu20Pd10, Hf70Cu20Pt10, Hf70Cu20Ag10, Hf73Pd27 and Hf73Pt27 amorphous alloys were prepared by a single roller melt-spinning method and the crystallization process was studied by differential scanning calorimetry (DSC), X-ray diffraction and transmission electron microscopy. A single exothermic 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 curves of Hf70Cu20Pd10, Hf70Cu20Pt10 and Hf73Pd27 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 since further annealing leads its transformation to other stable crystals. The relation among the atomic configurations of the amorphous alloy, I-phase and stable crystalline phases is discussed.