The effects of Si substitution on the glass forming ability of Ni–Pd–P system, a DFT study on crystalline related clusters

In order to investigate the influence of Si in the glass forming ability of Pd–Ni–P based bulk metallic glasses, the topological and electronic structure of stoichiometry related crystals is explored using density functional theory. The results indicate that Si based clusters based on a rich Pd environment with a symmetric configuration of the transition metal are the most stable, while P prefers a Ni rich environment with an asymmetric arrangement of the transition metals. Si tends to be at the center of the clusters, while in general the P atoms present a displacement toward some of the Ni atoms. The coordination of Si in rich Ni crystals is always higher than the one observed for P atoms. Also, the inclusion of Si induces a local pressure field in a radius of 14 Å leading to a disordered displacement of P from the equilibrium positions. The favoring of different competing crystals by adding Si, as well as the local pressure effect, suggests a mechanism on how devitrification is suppressed.