Kinetically facilitated liquid-liquid transition in a metallic liquid

Abstract

The subtle existence of a liquid-liquid transition in ‘homogeneous’ equilibrium metallic liquids is difficult to detect. An exothermic peak with the onset temperature above the equilibrium liquidus temperature is detected by in-situ ultrafast calorimetry in Yb-Zn liquid. The thermal event emerges on cooling, only. The exothermic event maintains a constant reversible part of the specific heat during modulated cooling, and it does not appear to be reversed on heating as no corresponding endothermic event is detected. The transition temperature lies about 6% above the equilibrium liquidus temperature and the detected enthalpy change of the transition is about 10−12% of the enthalpy of fusion for the highest cooling rates ∼104 K s−1 applied. The critical quenching temperature, below which the exotherm disappears on cooling, coincides with a liquid-liquid transition studied in the literature by other techniques. A phase diagram inclusive of the transition in the liquid is constructed by using calorimetry signals.