Composition dependence of polyamorphic transition in Pd-Ni-P metallic glasses

The complexity of polyamorphic transitions (PTs) in metallic glasses (MGs), particularly their intricate chemical effect, makes it challenging to understand the nature of PTs and the glass state in MGs. In this work, we systematically investigated the chemical dependence of thermally induced PTs in (PdNi)(100-x)P-x MGs, where P content varies from 15 to 21 at%. Differential scanning calorimetry analyses coupled with structure factor evolution indicate that reentrant glass transition occurring in alloys with a P content of < 17 at% is suppressed with an increase in P. The structural parameters fitted using extended X-ray absorption fine structure and in-situ synchrotron X-ray scattering measurements reveal that the composition dependence of reentrant glass transition originates from the metal-metalloid bond (i.e., Pd/Ni-P bonds) rearrangement and the consequent short-range ordering to medium-range ordering. This results in the coexistence of reentrant liquid-liquid and glass transitions in Pd4.15Ni41.5P17 MGs. This finding enriches our understanding of the atomic mechanism of reentrant glass transition and clarifies the confusion on the structural origin of PTs in the Pd-Ni-P system.