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

• Published in: The Journal of chemical physics Vol. 136; no. 10; p. 104509
• Main Authors: Lad, K N, Jakse, N, Pasturel, A
• Format: Journal Article
• Language: English
• Published: United States 14.03.2012
• ISSN: 1089-7690
• 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 τ 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 τ suggests a crossover from non-Arrhenius to Arrhenius behavior near mode-coupling transition temperature T(C), and (iii) the alloy exhibits a crossover from Stokes-Einstein ((D ~ (τ/T)(-1)) to fractional Stokes-Einstein (D ∝ (τ/T)(-ζ)) with exponent ζ ≈ 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.