Medium range order in Zr-noble metal eutectic liquids

The medium range order (MRO) in containerless-processed Zr-noble metal eutectic liquids has been measured using the Beamline Electrostatic Levitation (BESL) technique. High energy X-ray diffraction data were obtained for equilibrium and supercooled Zr75.5Pd24.5 and Zr80Pt20; Zr77Rh23 and Zr82Ir18; and Zr81Au19 liquids. When Zr is alloyed with 5d transition metals (Ir, Pt, Au) a prominent pre-peak in the X-ray static structure factor appears, indicating the presence of extended order. However, the position of the pre-peak is not consistent with size considerations alone. Given the similarities between the 4d and 5d alloying elements in atomic size and enthalpy of mixing with Zr, extended MRO likely exists in all of the compositions studied.