Formation of ultrafine nanostructure by crystallization of Zr₅₂Al₆Cu₁₄Ni₈Fe₂₀ metallic glass

The short-range order and the crystallization behavior of amorphous Zr₅₂Al₆CU₁₄Ni₈Fe₂₀ alloys have been investigated by means of calorimetry and x-ray diffraction. The amorphous structure transforms upon annealing without formation of long-range order. An ultrafine microstructure consisting of about 60 vol % cubic NiZr₂ crystal-like clusters with a size of 〈D〉≈2 nm embedded in a residual amorphous matrix phase forms as a first step of crystallization resulting from high nucleation rate combined with low growth velocity. In a second step growth of the clusters to crystals up to a mean diameter of 〈D〉≈4-5 nm takes place as a distinct process.