Investigation on structure and dynamic property of liquid Pd-Cu-Ni-P alloys using ab initio molecular dynamics simulation

Based on the short-range order, it is found that the abundance of the P-centered P-transition-metal clusters are the common feature among the liquid Pd-Cu-Ni-P alloys, and hence this feature alone could not uncover the underlying mechanisms of the variation of glass forming ability among the liquid alloys. For the so called similar elements such as Cu and Ni, their behaviors are significantly different when interacting with Pd or P atoms. Cu has weak bonding with both Pd and P while Ni has very strong bonding with P but nearly no bonding with Pd. The different bonding characters thus underlie the phenomenon that in the best glass formers the ratio of the two similar elements often deviates from 1:1. Only if the parameters of chemical short-range order of Cu and Ni around P become closest to each other the best glass forming ability is reached. It is also illustrated that the calculated dynamic properties are very helpful to locate the composition of the best glass former.