Internal clusters in crystalline phases related to Zr-based bulk amorphous alloys

The crystalline phases that form with the continuous heating of Zr-based bulk amorphous alloys were classified for the first time into three different groups based on the type of internal cluster, representing the locally ordered atoms within the unit cells of the crystalline phases: two-shell Bergman internal cluster in the face-centered cubic cF-Zr2Ni phase and ZrTiNi (C14-type) Laves phase, truncated octahedron internal cluster in the tetragonal phases of tI-Zr2Cu and tI-Zr2Pd, and Gaskell internal cluster (trigonal prism capped by three half octahedra) in the hexagonal phases of bP-Zr6Al2Ni and hP-ZrBe2. The phases with a similar internal cluster type were also found to have similar valence electron concentrations (ela), even though some crystalline structures are different from each other. The density of states for the primary phases calculated using the density functional theory indicated that the high stability of certain amorphous phases could be attributed to a difference in the internal cluster structure between the amorphous phases and the primary phases. (c) 2005 Elsevier B.V. All rights reserved.