High-energy diffraction measurements of deeply undercooled Co-Pd liquids using electrostatic levitation*

Co-Pd liquids in their deeply undercooled state have attracted a great deal of interest because of the potential for magnetically triggered nucleation of the solid phase. We report on the results of high-energy x-ray diffraction measurements, using 129 keV x-rays at the Advanced Photon source, on a series of liquid Co-Pd alloys in a containerless environment employing electrostatic levitation. Diffraction data were collected using a flat-plate two-dimensional detector during free cooling from temperatures well above the liquidus, to as much as 200 degrees C of undercooling for compositions ranging from 50:50 to 80:20 (Co:Pd). The composition dependence and temperature dependence of differences in structure will be discussed.