Correlation between primary phases and atomic clusters in a Zr-based metallic glass

Atomic clusters exiting in the Zr65Ti10Ni25 metallic glass and primary phases generated during crystallization were studied by x-ray scattering and high-resolution transmission microscopy. An intrinsic correlation between the atomic clusters and the primary phases has been revealed. It is found that there are topological icosahedral short-range orders (ISROs) in the as-cast sample in addition to fcc-Zr2Ni-type chemical SROs. These topological ISRO and fcc-Zr2Ni-type chemical SRO can simultaneously quasicrystallize/crystallize into the corresponding nanoscaled icosahedral quasicrystalline phase (I-phase) and fcc-Zr2Ni crystal as primary products during crystallization. The synchronic precipitation of these two metastable phases can be understood in terms of their structural similarity between the fcc-Zr2Ni and I-phase in local atomic configuration. In comparison with fcc-Zr2Ni crystal, the I-phase has a smaller size and lower volume fraction due to its lower growth rate attributed to its more complex composition and higher structural symmetry. The competitive growth between these two phases results in the development of nanostructured materials in this alloy after annealing. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3525985]