Medium range order in Zr-noble metal eutectic liquids

Abstract 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 Zr 75.5 Pd 24.5 and Zr 80 Pt 20 ; Zr 77 Rh 23 and Zr 82 Ir 18 ; and Zr 81 Au 19 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.