Evidence of liquid–liquid phase transition in Zr–Cu–Al melts and its link to glass-forming ability

Liquid–liquid phase transition (LLPT) has been found in two Zr–Cu–Al glass-forming metallic melts above the liquidus temperature, characterized by thermophysical, structural, and density changes by in situ high-energy synchrotron x-ray diffraction, electrostatic levitation, and molecular dynamics simulation. A correlation between LLPT and glass-forming ability has been established in the Zr–Cu–Al liquids. The better glass former, Zr₄₆Cu₄₆Al₈, exhibits more pronounced LLPT behavior accompanied by significant density and medium-range order changes, compared to the average glass former, Zr₅₆Cu₃₆Al₈. Our work shows how LLPT impacts the structural and thermodynamic properties of glass-forming melts at high temperature, shedding light on the origin of glass formation.