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Five-fold symmetry as indicator of dynamic arrest in metallic glass-forming liquids.

Hu YC, Li FX, Li MZ, Bai HY, Wang WH - Nat Commun (2015)

Bottom Line: Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses.Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition.A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190 China.

ABSTRACT
With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective.

No MeSH data available.


Related in: MedlinePlus

The evolution of five-fold local symmetry during quenching.The temperature dependence of W for the simulated systems showing similar trend but different values after glass transition.
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f1: The evolution of five-fold local symmetry during quenching.The temperature dependence of W for the simulated systems showing similar trend but different values after glass transition.

Mentions: To verify the universality of this structural parameter in amorphous state, eight typical MG-forming liquids, including NiP, NiZr, NiAl, PdSi, CuZrAl, ZrCuAg and MgCuY, were investigated (Methods). The total pair correlation functions of the simulated systems at 300 K (Supplementary Fig. 2) are different from each other manifesting different structures, which indicates the diversity of the investigated MG samples30. Figure 1 shows the temperature dependence of W in the simulated MG-forming liquids. It is clearly seen that W in all the simulated systems exhibits similar temperature-dependent behaviour, increasing rapidly above Tg and reaching constant values below Tg. However, the constant values of W below Tg are different in different metallic liquids, indicating that the degree of the five-fold symmetry is a material-dependent property and could be used to distinguish different MGs12. The temperature dependence of W represents the structural evolution of MG-forming liquids during glass transition.


Five-fold symmetry as indicator of dynamic arrest in metallic glass-forming liquids.

Hu YC, Li FX, Li MZ, Bai HY, Wang WH - Nat Commun (2015)

The evolution of five-fold local symmetry during quenching.The temperature dependence of W for the simulated systems showing similar trend but different values after glass transition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595736&req=5

f1: The evolution of five-fold local symmetry during quenching.The temperature dependence of W for the simulated systems showing similar trend but different values after glass transition.
Mentions: To verify the universality of this structural parameter in amorphous state, eight typical MG-forming liquids, including NiP, NiZr, NiAl, PdSi, CuZrAl, ZrCuAg and MgCuY, were investigated (Methods). The total pair correlation functions of the simulated systems at 300 K (Supplementary Fig. 2) are different from each other manifesting different structures, which indicates the diversity of the investigated MG samples30. Figure 1 shows the temperature dependence of W in the simulated MG-forming liquids. It is clearly seen that W in all the simulated systems exhibits similar temperature-dependent behaviour, increasing rapidly above Tg and reaching constant values below Tg. However, the constant values of W below Tg are different in different metallic liquids, indicating that the degree of the five-fold symmetry is a material-dependent property and could be used to distinguish different MGs12. The temperature dependence of W represents the structural evolution of MG-forming liquids during glass transition.

Bottom Line: Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses.Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition.A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190 China.

ABSTRACT
With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective.

No MeSH data available.


Related in: MedlinePlus