The glass-forming ability of model metal-metalloid alloys

TL;DR

This study uses molecular dynamics simulations with a simplified model to identify conditions favoring the formation of bulk metallic glasses in metal-metalloid alloys, aligning with experimental observations.

Contribution

It introduces a computational approach to predict glass-forming ability in metal-metalloid alloys, enabling efficient exploration of alloy compositions.

Findings

Optimal glass formers occur at specific atomic size ratios and metalloid fractions.

The model's predictions match experimental glass-forming regimes.

The approach facilitates combinatorial searches for new BMGs.

Abstract

Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio $\sigma_S/\sigma_L$ and number fraction $x_S$ of the metalloid species. We show that the regime in the space of $\sigma_S/\sigma_L$ and $x_S$ where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures coincides with that for experimentally observed metal-metalloid glass formers. Our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.