Structural basis for supercooled liquid fragility established by synchrotron-radiation method and computer simulation

Metallic melts above the liquidus temperature exhibit nearly Arrhenius-type temperature dependence of viscosity. On cooling below the equilibrium liquidus temperature metallic melts exhibit a non-Arrhenius temperature dependence of viscosity characterized by liquid fragility phenomenon which origin is still not well understood. Structural changes and vitrification of the Pd42.5Cu30Ni7.5P20 liquid alloy on cooling from above the equilibrium liquidus temperature are studied by synchrotron radiation X-ray diffraction and compared with the results of first-principles calculations. Subsequent analysis of the atomic and electronic structure of the alloy in liquid and glassy states reveals formation of chemical short-range order in the temperature range corresponding to such a non-Arrhenius behavior. The first-principles calculations were applied to confirm the experimental findings. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624745]