Increased stability of CuZrAl metallic glasses prepared by physical vapor deposition

TL;DR

This study uses molecular dynamics simulations to demonstrate that vapor deposition produces CuZrAl metallic glasses with higher density, stability, and specific structural features compared to traditional melt-quenching, offering a more efficient fabrication method.

Contribution

The paper introduces a vapor deposition simulation approach that yields more stable CuZrAl metallic glasses with distinct chemical and structural properties, surpassing melt-quenching methods.

Findings

VD glasses have higher density and lower potential energy.

VD glasses show more icosahedral clusters than melt-quenched glasses.

Chemical order in VD glasses differs from melt-quenched ones, with more Zr-Zr bonds.

Abstract

We carried out molecular dynamics simulations (MD) using realistic empirical potentials for the vapor deposition (VD) of CuZrAl glasses. VD glasses have higher densities and lower potential and inherent structure energies than the melt-quenched glasses for the same alloys. The optimal substrate temperature for the deposition process is 0.625$\times T_\mathrm{g}$. In VD metallic glasses (MGs), the total number of icosahedral like clusters is higher than in the melt-quenched MGs. Surprisingly, the VD glasses have a lower degree of chemical mixing than the melt-quenched glasses. The reason for it is that the melt-quenched MGs can be viewed as frozen liquids, which means that their chemical order is the same as in the liquid state. In contrast, during the formation of the VD MGs, the absence of the liquid state results in the creation of a different chemical order with more Zr-Zr homonuclear bonds compared with the melt-quenched MGs. In order to obtain MGs from melt-quench technique with similarly low energies as in the VD process, the cooling rate during quenching would have to be many orders of magnitude lower than currently accessible to MD simulations. The method proposed in this manuscript is a more efficient way to create MGs by using MD simulations.