Increased stability of CuZrAl metallic glasses prepared by physical vapor deposition

• Published in: Journal of alloys and compounds 2017-12, Vol.728, p.1110-1115
• Main Authors: Bokas, G.B., Zhao, L., Morgan, D., Szlufarska, I.
• Format: Article
• Language: English
• Subjects: Alloys; Amorphous materials; Chemical bonds; Chemical vapor deposition; Cooling rate; Icosahedral phase; Metallic glass; Metallic glasses; Molecular dynamics; Molecular dynamics simulations; Physical vapor deposition; Quenching; Quenching (cooling); Rapid-solidification; Short-range order; Simulation; Solidification; Zirconium
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2017.09.068

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 × Tg. 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. •Physical vapor deposited glass is energetically more stable than melt-quenched glass.•Chemical ordering is different in vapor deposited and melt-quenched glasses.•Physical vapor deposited simulations provide a pathway for making glass models.