Atomic structure of glassy Mg₆₀Cu₃₀Y₁₀ investigated with EXAFS, x-ray and neutron diffraction, and reverse Monte Carlo simulations

Short range order of amorphous Mg₆₀Cu₃₀Y₁₀ was investigated by x-ray and neutron diffraction, Cu and Y K-edge x-ray absorption fine structure measurements, and the reverse Monte Carlo simulation technique. We found that Mg-Mg and Mg-Cu nearest neighbor distances are very similar to values found in crystalline Mg₂Cu. The Cu-Y coordination number is 1.1±0.2, and the Cu-Y distance is ~4% shorter than the sum of atomic radii, suggesting that attraction between Cu and Y plays an important role in stabilizing the glassy state. Thermal stability and structure evolution upon annealing were also studied by differential scanning calorimetry and in situ x-ray powder diffraction. The alloy shows a glass transition and three crystallization events, the first and dominant one at 456  K corresponding to eutectic crystallization of at least three phases: Mg₂Cu and most likely cubic MgY and CuMgY. ©2007 The American Physical Society