Fig. 3
Evolution of structural order in metallic glass-forming liquids. a Fraction of total atoms involved with the characteristic short-range order (atomic packing motifs) in Cu64Zr36 and Mg65Cu25Y10 liquids as a function of temperature (normalized by T g). In Cu64Zr36 liquid, the characteristic atomic motif is Cu-centered FI (full icosahedra, with Voronoi index <0, 0, 12, 0>); in Mg65Cu25Y10 liquid, the characteristic atomic motif is BSAP (with Voronoi index <0, 2, 8, 0>) and TTP (tricapped trigonal prisms, with Voronoi index <0, 3, 6, 0>); see refs. 30, 31 for simulation details; b Evolution of the average number of cluster connections in Cu64Zr36 and Mg65Cu25Y10 liquids with decreasing temperature; 3-atom or 2-atom refers to the number of shared atoms by two interconnected coordination polyhedra; The detailed definition of cluster connection can be found in ref. 70; c For various metallic glass-forming liquids, the larger the structural fragility γ, the more fragile the liquids (reflected by smaller D* or larger m), and vice versa. The inset is adapted from ref. 28, showing a large discrepancy between the height of the first peak, S(q 1), in the liquid when extrapolated to T g and that measured in the glass (see Equation (4) and ref. 28). d The static structure factor and the height of the first peak for Cu64Zr36 liquid are plotted as a function of temperature; the γ is obviously larger for Cu64Zr36 than for Mg65Cu25Y10 (also included for comparison). As such, the two MD-simulated liquids shown in a provide data points down to T g, and lend support to the observations made by Mauro et al.28 based on experimental measurements (Fig. 3c)
