Atomic structure of nanoscale quasicrystal-forming Zr-noble metal binary metallic glasses

We report the results of the local structural evaluation and mechanism of QC formation in the Zr₇₀Pd₃₀ and Zr₈₀Pt ₂₀ glassy alloys. Voronoi analysis indicates the difference of local environment between two alloys. The perfect icosahedron frequently exists around Zr atom and major polyhedra have prism-like structure around Pd in Zr ₇₀Pd₃₀. In contrast, icosahedral-like distorted polyhedra formation is favorable around Pt as well as Zr in Zr₈₀Pt ₂₀. It is therefore, concluded that the quasicrystallization originates from the medium-range order based on the Zr-centered perfect icosahedron and the Pd-centered prism-like ones remain during the QC phase formation in Zr₇₀Pd₃₀. Icosahedral-like local structure around Zr and Pt might contribute together to the nucleation of QC phase in Zr₈₀Pt₂₀. This feature with a different mechanism of QC formation in the two alloys may correlate to the difference of solute concentration and the structure of stable crystalline phase after the decomposition of QC phase.