Short-range order structure motifs learned from an atomistic model of a Zr50Cu45Al5 metallic glass

Abstract

The structural motifs of a Zr50Cu45Al5 metallic glass were learned from atomistic models using a new structure analysis method called motif extraction that employs point-pattern matching and machine learning clustering techniques. The motifs are the nearest-neighbor building blocks of the glass and reveal a well-defined hierarchy of structures as a function of coordination number. Some of the motifs are icosahedral or quasi-icosahedral in structure, while others take on the structure of the most close-packed geometries for each coordination number. These results set the stage for developing clearer structure-property connections in metallic glasses. Motif extraction can be applied to any disordered material to identify its structural motifs without the need for human input.

Impact of Severe Deformation by HPT at Room Temperature on the Relaxation of the Glassy and the Supercooled Liquid States of PdNiP

“…Their origin is now discussed. Recent molecular dynamics (MD) simulations showed that at the glass transition the motif distribution in metal-metal MGs changed towards an increase in "icosahedral-like" order in the supercooled liquid 63 . On the other hand, for metalmetalloid MGs the influence of covalent bonding seems to be the key parameter leading to a frustration of icosahedral structures 7,58,[64][65][66] .…”

X-ray photon correlation spectroscopy revealing the change of relaxation dynamics of a severely deformed Pd-based bulk metallic glass

“…geometrical differences can be resolved by motif extraction, which revealed that a collection of motifs coexist in the MG system and each motif possesses a certain population and a propensity of motion[64][65][66][67]. The glass transition or a plastic deformation process should be accompanied by a geometrical change of the motif configuration, resulting in an increase or decrease of the population of specific motifs, and should also be simultaneously accompanied by a change of the correlation length of motifs (i.e.…”

What renders bulk metallic glass ductile/brittle? -- new insight from the medium-range order

“…A molecular dynamics (MD) simulation came to a similar conclusion, finding the coexistence of P-centered polyhedra, that is tricapped trigonal prisms, and densely packed Ni-centered icosahedra leading to a topological order between these two clusters 44 . Furthermore, it was observed by another MD simulation combined with the recently developed motif extraction that for some motifs the population was strongly altered by by-passing the glass transition using an ultrafast cooling 45,46 . It seems that for the metal-metalloid case, a bicapped square antiprism motif (in addition to the icosahedral motif 45 ) plays a significant role in the glass transition 46 .…”

“…Furthermore, it was observed by another MD simulation combined with the recently developed motif extraction that for some motifs the population was strongly altered by by-passing the glass transition using an ultrafast cooling 45,46 . It seems that for the metal-metalloid case, a bicapped square antiprism motif (in addition to the icosahedral motif 45 ) plays a significant role in the glass transition 46 . The influence of covalent bonding seems to be the key parameter for the frustration of icosahedral structures 46,47 .…”