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M: Metallphysik

M 22: Symposium on Structurally Complex Alloy Phases IV (SCAP IV)

M 22.3: Fachvortrag

Donnerstag, 14. März 2002, 16:30–16:45, H16

Formation of complex phases by crystallization of zirconium based metallic glasses — •Norbert Mattern, Uta Kuehn, and Juergen Eckert — Institut fuer Festkoerper- und Werkstofforschung Dresden, Postfach 270016, 01171 Dresden

Complex intermetallic phases may be formed by the crystallization of amorphous zirconium based alloys. The mechanical properties of these materials are strongly influenced by the different phases, but their crystallographic structure is not understood in detail until now. We investigated the thermal behavior and the phase formation of amorphous Zr-Ti-Cu-Ni-Al alloys upon heat treatment. Depending on small changes in the chemical composition, different metastable phases are formed from the amorphous as-cast state during annealing: quasicrystalline phases,tetragonal or hexagonal phases derived from the bcc structure (beta-Ti type), a big cubic phase of the NiTi2-type (96 atoms per unit cell), and further phases with unknown crystal structure. The determination of radial atomic pair correlation functions indicate similar short-range order in the quasicrystalline and crystalline multicomponent phases. The different crystal structures are discussed in relationship to differences in the linkage of the polyhedra.