Icosahedral medium-range order formed in Mg₇₀Zn₃₀metallic glass: a larger-scale molecular dynamics simulation

Abstract

Hou Zhao-Yang(侯兆阳) a) † , Liu Rang-Su(刘让苏) b) , Tian Ze-An(田泽安) b) , and Wang Jin-Guo(王晋国) a)

Atomic structure of biodegradable Mg-based bulk metallic glass

“…Icosahedral structural motifs are known to be prevalent in related glass compositions [19][20][21][22] and in metallic glasses more generally [23][24][25], where their presence is linked to increased glass-forming ability. For these compositions, they occurred in rather low numbers, typically less than 10%, although due to the very wide range of local atomic structures, icosahedra and related environments were among the most common observed.…”

“…This will require the use of empirical potentials such as those previously developed for related systems [19][20][21]28]; these potentials require careful validation before use and the data obtained in this paper will be invaluable to achieve this, through, e.g. comparison of the interatomic forces simulated classically and ab initio.…”

“…It is clear that to characterise fully the medium-range structural environment, as well as elucidate any composition-dependent changes, we will need to study larger models of these glasses. This will require the use of empirical potentials such as those previously developed for related systems; [19][20][21]28 these potentials require careful validation before use and the data obtained in this paper will be invaluable to achieve this, through, e.g. comparison of the interatomic forces simulated classically and ab initio.…”

“…[14][15][16][17][18] Despite this interesting application, the structure of Mg-Zn-Ca glasses is not yet fully understood. Initial studies were focussed on Mg-Zn binary glasses, in which empirical interatomic force fields have been used to show that icosahedral structural motifs are the dominant local configuration in the binary glass Mg 70 Zn 30 , [19][20][21] and icosahedra have also been shown by first-principles MD to dominate in Mg 90 Ca 10 glass, 22 where some were also seen to arrange in an ordered way leading to a quasicrystalline phase. The presence of icosahedra is also seen in metallic glasses more generally, [23][24][25] and their presence is often linked to increased GFA.…”

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

“…Most importantly, the fraction of SRO units assigned to this motif increases significantly with temperature, significantly more strongly than the quasi-icosahedral motif 12B, but not nearly as strongly as motif 12A Z . SRO units with VI <0 2 8 0> have been identified as important in various other studies [3,[63][64][65][66][67]. The significant increase in relative population of this motif indicates that it may play an important role in the structure of Zr-Cu-based MGs as well, so this motif may deserve more attention in future studies.…”