‘Structure determines properties’ is a cornerstone of materials science. For crystalline metals, the periodic arrangement of atoms constitutes a lattice structure, facilitating the establishment of its causal relationship with electronic, mechanical and transport properties. However, this paradigm faces a formidable challenge when crossing the boundary into the disordered world of metallic glasses (MGs) [1–3]. Researchers have long sought to decode hidden order in disorder; they have deciphered the ‘structure’ primarily based on atomic packing motifs, for example the dominant ones that promote the metastability of the glassy state, or the geometrically unfavored ones that tend to respond first to externally imposed stress fields due to their far-from-normal coordination number (CN) [4]. In general, the locally favored structures arise from not only topological short-range order (SRO) to achieve high packing efficiency, but also chemical SRO to maximize preferred bonds and minimize disliked neighbors. The cooperation of these two SRO aspects, together, determines which atomic species and how many of them (CN) form the nearest-neighbor shell making up the coordination polyhedra. Furthermore, the representative motifs must also satisfactorily account for all the constituent elements in their correct molar proportions (i.e. the local chemical make-up should match the alloy composition). Both the geometrical and chemical attributes are expected to influence the flexibility of the local structure [5], when it comes to correlating with the deformability and relaxation dynamics of the glass [4,5].

Link:When glass relaxation is governed by chemical bonding heterogeneity | National Science Review | Oxford Academic