Temperature-Dependent Structural Evolution in Au₄₄Ga₅₆ Liquid Eutectic Alloy

Temperature-dependent short-range structural evolution of Au₄₄Ga₅₆ liquid eutectic alloy has been studied by in situ extended X-ray absorption fine structure (EXAFS), in situ high-energy X-ray diffraction (HEXRD) together with first-principles molecular dynamics (FPMD) simulations. It is found that the short-range structure of Au₄₄Ga₅₆ liquid strongly inherits the local atomic packing of the AuGa compound. A short-range structural change in Ga-centered clusters is revealed by in situ EXAFS data at the Ga K-edge at about 970 K, while no such change in Au-centered clusters appears at the Au L_III-edge. The in situ HEXRD and FPMD simulations also confirm the existence of a liquid-to-liquid crossover (LLC) in the Au₄₄Ga₅₆ liquid at a temperature range of about 1000-1100 K, mainly lying in the local structural change around Ga atoms. Indeed, the alloys quenched from the liquid phases below 1000 K and above 1100 K exhibit differences in structure and magnetic properties, which opens a possibility to fabricate new materials with different structures and properties in LLC-containing alloys.