Nucleation and thermal stability of an icosahedral nanophase during the early crystallization stage in Zr-Co-Cu-Al metallic glasses

Z. Wang, S. V. Ketov, C. L. Chen, Y. Shen, Y. Ikuhara, A. A. Tsarkov, D. V. Louzguine-Luzgin, J. H. Perepezko

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

The early stage of crystallization in amorphous phases is a key step in the overall microstructural evolution. In a Zr-based amorphous alloy the formation of metastable nanophase was observed at the earliest crystallization stage, with an ultra-high nucleation density of 6.5 × 1024 m−3 and a size of ∼1–2 nm. The nanophase has an icosahedral structure and exhibits an extremely high thermal stability up to 150 K above the crystallization onset. The chemical and structural heterogeneity in the early stage of the glass crystallization were observed using high-resolution high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM), which can be applied to study materials with atomic resolution. A nucleation kinetics analysis of the nanophase formation accounts for the high product number density and indicates a low interface energy value between the metastable clusters and the amorphous matrix, σa,i of 14 mJ/m2. The thermal stability and resistance to size change by growth or coarsening are attributed to a stalled growth due to solute depletion and the low σa,i value. With the high nucleation rate and the low barrier, it is remarkable that the kinetics follow conventional nucleation theory.

Original languageEnglish
Pages (from-to)298-306
Number of pages9
JournalActa Materialia
Volume132
DOIs
Publication statusPublished - 2017 Jun 15

Keywords

  • Crystallization
  • Icosahedral structure
  • Metallic glasses
  • Nucleation kinetics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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