Different Thermal Responses of Local Structures in Pd₄₃Cu₂₇Ni₁₀P₂₀ Alloy from Glass to Liquid

Different thermal responses of local atomic packing structures in a Pd₄₃Cu₂₇Ni₁₀P₂₀ alloy from glass to liquid have been studied by in situ high-energy X-ray diffraction together with ab initio molecular dynamics simulations in details. The expansion behaviors of high-coordination shells are close to the whole sample. However, atoms in the first two nearest neighboring shells exhibit diverse thermal responses below and above the glass transition. The ab initio molecular dynamics simulations reveal various cluster evolutions of P-centered and Pd-, Cu-, and Ni-centered clusters which lead to diverse expansion behaviors of the nearest neighboring atoms. Diverse evolutions of these clusters could also affect their connection schemes, which are inclined to become lower coordinated clusters connected with adjacent clusters by sharing two atoms in the supercooled and equilibrium liquid, resulting in diverse expansion behaviors of the second nearest neighboring atoms. Moreover, the enlargement of the included angle among three clusters upon heating could increase the free volumes between two side clusters, leading to relatively large position shifts of the third, fourth, and fifth shells.