Abstract
Vitrification from physical vapor deposition is known to be an efficient way for tuning the kinetic and thermodynamic stability of glasses and significantly improve their properties. There is a general consensus that preparing stable glasses requires the use of high substrate temperatures close to the glass transition one, Tg. Here, we challenge this empirical rule by showing the formation of Zr-based ultrastable metallic glasses (MGs) at room temperature, i.e., with a substrate temperature of only 0.43Tg. By carefully controlling the deposition rate, we can improve the stability of the obtained glasses to higher values. In contrast to conventional quenched glasses, the ultrastable MGs exhibit a large increase of Tg of ∼60 K, stronger resistance against crystallization, and more homogeneous structure with less order at longer distances. Our study circumvents the limitation of substrate temperature for developing ultrastable glasses, and provides deeper insight into glasses stability and their surface dynamics.
Highlights
Vitrification from physical vapor deposition is known to be an efficient way for tuning the kinetic and thermodynamic stability of glasses and significantly improve their properties
The fact that just one order of magnitude lower rate of deposition generates a huge enhancement in glass stability even at a Tsub far below the Kauzmann temperature[30] (Fig. 1b), questions the argument of an underlying thermodynamic mechanism governing the formation of stable glasses[11]
In numerical simulations[31], it was found that the optimal Tsub for a given deposition rate decreases as deposition slows, suggesting a competition between thermodynamics and kinetics
Summary
Zr46Cu46Al8 MGs: ordinary glass produced by melt-spinning technic; vapor-deposited glass films at different rates as denoted below each curve. Chemical analysis (Thermo IRIS Intrepid II XSP) confirmed that the compositions of the vapor-deposited glass films are identical to that of the ordinary glass ribbon prepared by melt-spinning method within 1% error (Supplementary Table 1). This is further ascertained by their similar melting temperatures (Supplementary Figure 1). The magenta curve is for the ordinary glass prepared by liquid quenching, and its Tg is 698 K consistent with previous reports[20]. The other DSC curves are for glass films synthesized by vapor deposition at different rates. As can the be seen, Tg increases with deposition rate is 10.67 nm decreasing min−1, the deposition rate. glass film has a
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