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The L–G phase transition in binary Cu–Zr metallic liquids
The authors recently reported that undercooled liquid Ag and Ag–Cu alloys both exhibit a first order phase transition from the homogeneous liquid (L-phase) to a heterogeneous solid-like G-phase under isothermal evolution. Here, we report a similar L–G transition and heterogenous G-phase in simulations of liquid Cu–Zr bulk glass. The thermodynamic description and kinetic features (viscosity) of the L-G-phase transition in Cu–Zr simulations suggest it corresponds to experimentally reported liquid–liquid phase transitions in Vitreloy 1 (Vit1) and other Cu–Zr-bearing bulk glass forming alloys. The Cu–Zr G-phase has icosahedrally ordered cores versus fcc/hcp core structures in Ag and Ag–Cu with a notably smaller heterogeneity length scale Λ . We propose the L–G transition is a phenomenon in metallic liquids associated with the emergence of elastic rigidity. The heterogeneous core–shell nano-composite structure likely results from accommodating strain mismatch of stiff core regions by more compliant intervening liquid-like medium.
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NSF-PAR ID:
10312303
Journal Name:
Physical Chemistry Chemical Physics
Volume:
24
Issue:
1
ISSN:
1463-9076
4. When aged below the glass transition temperature,$Tg$, the density of a glass cannot exceed that of the metastable supercooled liquid (SCL) state, unless crystals are nucleated. The only exception is when another polyamorphic SCL state exists, with a density higher than that of the ordinary SCL. Experimentally, such polyamorphic states and their corresponding liquid–liquid phase transitions have only been observed in network-forming systems or those with polymorphic crystalline states. In otherwise simple liquids, such phase transitions have not been observed, either in aged or vapor-deposited stable glasses, even near the Kauzmann temperature. Here, we report that themore »