Abnormal endothermic liquid–liquid phase transition upon cooling Pd40Ni40P20 melts

Abstract

Liquid–liquid phase transition (LLPT) is the transformation of a liquid from one distinctive structure to another with the same composition. However, the origin of the structural variation at LLPT is still controversial. Here, we used ab initio molecular dynamics simulation to verify and investigate a high-temperature LLPT in a Pd40Ni40P20 melt; this melt showed a reduction in the nuclei interference of the conventional low-temperature LLPT. An abnormal endothermic LLPT was confirmed with flash differential scanning calorimetry, indicating a change in the atomic short-range-order structure around the P–P bond and a decrease in the number of specific icosahedral-like clusters, such as ⟨0 2 8 0⟩ and ⟨0 2 8 1⟩. The structural change of the P-centered clusters changed the solidification path through potential energy adjustments. Our results showed the structural mechanism of the unusual endothermic phenomenon and provided a different insight into regulating the properties of metallic glasses.