Impact of Spatial Dimension on Structural Ordering in Metallic Glass

TL;DR

This study uses molecular dynamics simulations to explore how reducing the spatial dimension from 3D to 2D affects the structural ordering and glass transition in metallic glasses, revealing distinct mechanisms in 2D.

Contribution

It uncovers a new structural mechanism involving crystal-like ordering in 2D metallic glasses, different from the 3D case, advancing understanding of dimensional effects on glass formation.

Findings

Crystal-like ordering influences dynamics in 2D MGs

2DMGs exhibit Mermin-Wagner fluctuations similar to 3D

Distinct structural mechanisms differentiate 2D and 3D MGs

Abstract

Metallic glasses have so far attracted considerable attention for their applications as bulk materials. However, new physics and applications often emerge by dimensional reduction from three dimension (3D) to two dimension (2D). Here, we study, by molecular dynamics simulations, how the liquid-to-glass transition of a binary Cu50Zr50 MG is affected by spatial dimensionality. We find clear evidence that crystal-like structural ordering controls both dynamic heterogeneity and slow dynamics, and thus plays a crucial role in the formation of the 2DMG. Although the 2DMG reproduces the dynamical behaviors of its 3D counterpart by considering Mermin-Wagner-type fluctuations specific to 2D, this atomic-scale structural mechanism is essentially different from that for the 3DMG in which icosahedral clusters incompatible with crystallographic symmetry play a key role in glassy behaviors. Our finding provides a new structural mechanism for the formation of 2DMGs, which cannot be inferred from the knowledge of 3DMGs. The results suggest a structural basis for the glass transition in 2DMG and provide possible explanations for some previous experimental observations in ultrathin film MGs.