Local atomic structures in amorphous and quasicrystalline Zr₇₀Ni₁₀Pt₂₀ and Zr₈₀Pt₂₀ alloys by the anomalous X-ray scattering method

Local atomic structures around Zr and Pt in a quasicrystalline Zr₈₀Pt₂₀ alloy, and amorphous and quasicrystalline Zr₇₀Ni₁₀Pt₂₀ alloys have been determined by the anomalous x-ray scattering (AXS) method. A distinct prepeak observed in an intensity profile of the amorphous Zr₇₀Ni₁₀Pt₂₀ alloy indicates existence of strong chemical short-range order (CSRO) clusters in the amorphous phase. Total coordination numbers around Zr and Pt in a nearest neighbor region in both alloys have been evaluated. The values around Pt are almost equal to 12 in the amorphous and quasicrystalline states suggest formation of icosahedral clusters around Pt. Some of crystalline structures formed from the quasicrystalline phases by annealing consist of icosahedral clusters of Zr and Ni atoms, or polyhedral clusters of Zr and Pt atoms similar with icosahedral clusters. The present result appears to support that the phase transformation from the amorphous to the crystal through the quasicrystal is explained by the icosahedral CSRO clusters in the amorphous and quasicrystalline states.