⇦Chinese Physics Letters, 2022, Vol. 39, No. 11, Article code 119901 Comment on “High Mixing Entropy Enhanced Energy States in Metallic Glasses” Ramir Ristić1 and Emil Babić2* Affiliations 1Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, HR-31000 Osijek, Croatia 2Department of Physics, Faculty of Science, Bijenička cesta 32, HR-10002 Zagreb, Croatia Received 27 April 2022; accepted manuscript online 8 October 2022; published online 24 October 2022 *Corresponding authors. Email: ebabic@phy.hr Citation Text: Ristić R and Babić E 2022 Chin. Phys. Lett. 39 119901    Abstract
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 DOI:10.1088/0256-307X/39/11/119901 © 2022 Chinese Physics Society Article Text A recent paper by Huo et al.[1] reported a correlation between the entropy of mixing, $\Delta S_{\rm mix}$ (and the corresponding energy state) and the thermal stability and mechanical parameters, for three Zr–Ti–Cu–Ni–Be metallic glasses (MGs) including a high-entropy metallic glass (HEMG). Namely, monotonic increases in the thermal stability and strength with $\Delta S_{\rm mix}$ were observed. Although the enhancement of thermal stability of HEMGs by $\Delta S_{\rm mix}$ has already been proposed[2,3] (see Ref. [4] for an alternative explanation) and the correlation between the thermal stability and mechanical parameters of MGs has been well established,[4-13] the correlation reported in Ref. [1] is potentially important and deserves further experimental verification.
cpl-39-11-119901-fig1.png
Fig. 1. The variation of initial crystallization temperature $T_{x}$ and yield strength $\sigma_{y}$ of Zr$_{20}$Ti$_{20}$Cu$_{20}$Ni$_{20}$Be$_{20}$, Zr$_{41}$Ti$_{14}$Cu$_{12.5}$Ni$_{10}$Be$_{22.5}$ and Ti$_{40}$Zr$_{25}$Cu$_{12}$Ni$_{3}$Be$_{20}$ (Ti40) metallic glasses[1] with total content of Cu and Ni, $x=x_{_{\scriptstyle \rm Cu}}+x_{_{\scriptstyle \rm Ni}}$.
The authors of Ref. [1] dismissed a possible compositional contribution to the variations of the thermal stability and mechanical parameters studied [Figs. 1(b) and 4, Table 1 of Ref. [1]], which, as illustrated in Fig. 1, may not be justified. As seen in Fig. 1, the variations of the crystallization temperature $T_{x}$ and the yield strength $\sigma_{y}$ with the total amount of late transition metals (TLs), $x=x_{_{\scriptstyle \rm Cu}}+x_{_{\scriptstyle \rm Ni}}$ (in atomic percent), are qualitatively the same as the variations with $\Delta S_{\rm mix}$ in Figs. 1(b) and 4(a) in Ref. [1]. The same is true for all other parameters studied in Ref. [1]. The increases of the thermal stability and the mechanical parameters of MGs combining early transition metals (TE = Ti, Zr, and Hf) and late ones (TL=Co, Ni, and Cu), with the increasing TL content, are well known and reflect the enhancement of interatomic bonding on alloying (amorphous) TEs with TLs.[4,7-14] This enhancement is specific to TE-TL MGs and does not depend on the number of components in a given alloy.[4,15-17] Thus, it is unlikely to be caused only by changes in the entropy of mixing. A study of a new Ti$_{40}$Zr$_{12}$Cu$_{25}$Ni$_{3}$Be$_{20}$ MG may provide a simple way of determining the contributions of $x$ and $\Delta S_{\rm mix}$ to the thermal stability and strength of TE-TL MGs since this alloy has the same $\Delta S_{\rm mix}$ as the alloy Ti40 in Ref. [1], while having considerably larger $x=28$ compared to that of Ti40 ($x=15$). Acknowledgment. We thank Professor J. R. Cooper for critical reading of this Comment. References High Mixing Entropy Enhanced Energy States in Metallic GlassesNonisothermal crystallization kinetics, fragility and thermodynamics of Ti20 Zr20 Cu20 Ni20 Be20 high entropy bulk metallic glassHigh thermal stability and sluggish crystallization kinetics of high-entropy bulk metallic glassesElectronic structure and properties of (TiZrNbCu)1-xNix high entropy amorphous alloysUniversal criterion for metallic glass formationCorrelations between elastic moduli and properties in bulk metallic glassesCorrelation between mechanical, thermal and electronic properties in Zr–Ni, Cu amorphous alloysSimple correlation between mechanical and thermal properties in TE–TL (TE=Ti,Zr,Hf;TL=Ni,Cu) amorphous alloysIdeal solution behaviour of glassy Cu–Ti, Zr, Hf alloys and properties of amorphous copperMagnetic susceptibility and atomic structure of paramagnetic Zr–(Co,Ni,Cu) amorphous alloysThermodynamic properties and atomic structure of amorphous zirconiumProperties and atomic structure of amorphous early transition metalsStructure property relationship in (TiZrNbCu) 1− x Ni x metallic glassesTransition from high-entropy to Cu-based (TiZrNbNi) 1− x Cu x metallic glassesTransition from high-entropy to conventional (TiZrNbCu) 1− x Co x metallic glassesTransition from High-Entropy to Conventional Alloys: Which Are Better?
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