EXAFS studies on local atomic structure in the amorphous Mg₆₅Cu₂₅Gd₁₀ alloy

Abstract

Local atomic structures of an amorphous Mg₆₅Cu₂₅Gd₁₀ alloy and the structural changes by thermal annealing have been studied by extended X-ray absorption fine structure (EXAFS). The correlation between structural changes and mechanical properties for the Mg₆₅Cu₂₅Gd₁₀ alloy has also been discussed. Results showed that Cu atoms around Gd in Mg₆₅Cu₂₅Gd₁₀ lost rapidly during annealing, resulting in the segregation of Cu atoms. The coordination number NGd-Mg of Mg₆₅Cu₂₅Gd₁₀ annealed at 373 K first diminished and then augmented with the increase of annealing time. The formation of polyhedral short-range order unit with coordination number of nearly 12 around Gd atoms is in favor of the improvement of mechanical properties. The chemical short-range order, not topological short-range order in the amorphous Mg₆₅Cu₂₅Gd₁₀ alloy had obvious changes during annealing.

Keywords

magnesium alloy / amorphous alloy / short-range / EXAFS / mechanical properties / annealing

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