Signatures of fragile-to-strong transition in a binary metallic glass- forming liquid

KN Lad and N Jakse and A Pasturel, JOURNAL OF CHEMICAL PHYSICS, 136, 104509 (2012).

DOI: 10.1063/1.3692610

Classical molecular dynamics investigations of the evolution of the microscopic structure and atomic dynamics are found to provide signatures of fragile-to-strong transition in a Cu-Zr bulk metallic glass forming alloy. Present study reveals that (i) the alloy exhibits a non-monotonic decoupling of the self-diffusion coefficient D and the relaxation time tau as observed in case of supercooled water despite the difference in the intermolecular interactions compared to this system, (ii) the temperature dependence of D and tau suggests a crossover from non-Arrhenius to Arrhenius behavior near mod-ecoupling transition temperature T-C, and (iii) the alloy exhibits a crossover from Stokes- Einstein ((D similar to (tau/T)(-1)) to fractional Stokes-Einstein (D alpha (tau/T)(-zeta)) with exponent zeta approximate to 0.6. A weak first-order transition, associated with the fragile-to-strong transition, has also been observed in the undercooled region. These findings are in accordance with the growing idea of fragile-to-strong crossover having larger generality than the traditional classification of the glass-forming liquids as fragile and strong. (C) 2012 American Institute of Physics.

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