2013 Volume 54 Issue 8 Pages 1351-1355
Au65Cu18Si17 bulk metallic glass (BMG) exhibits an extraordinary low glass transition temperature (<100°C) and a wide supercooled liquid region. In order to elucidate the structural features of the extraordinary low glass transition temperature and high glass forming ability of the Au65Cu18Si17 BMG, high-energy X-ray diffraction (HEXRD) and Extended X-ray Absorption Fine Structure (EXAFS) measurements were carried out using synchrotron radiation. A sharp first peak and oscillation of the structure factor S(Q) up to the high wave number Q can be attributed to the dominant weighting factor of the Au–Au correlation over others. A reverse Monte Carlo (RMC) simulation was applied simultaneously to the HEXRD and EXAFS data. The obtained RMC model shows a quite highly dense packed structure with large amount of icosahedral type clusters around Au atoms while small ones around Si atoms. The partial Cu–Cu pair distribution function gCu,Cu(r) shows a sharp peak at a short interatomic distance, i.e., 2.38 Å. The Cu–Cu pairs with short interatomic distances and the large thermal fluctuation around Cu atoms are considered to be one of the structural characteristics of the low glass transition temperature of the Au65Cu18Si17 BMG.