Structure and relaxation of the metallic glass Pd₅₂Ni₃₂P₁₆ modelled by reverse Monte Carlo simulation

Abstract

Atomistic models of the structure of a ternary metallic glass (Pd₅₂Ni₃₂P₁₆) before and after thermal relaxation have been determined by means of the reverse Monte Carlo simulation technique. Neutron diffraction data taken at different relaxation stages were used as input. Although the structure of this ternary alloy is found to be very similar to that in binary metallic glasses, the results indicate the different roles of Pd and Ni, both in the structure itself and during structural relaxation. Ni atoms display a relatively high degree of short-range order in the as-quenched state. Upon structural relaxation, metal-Pd-metal triplets show sharper distributions around the average nearest-neighbour distances and 60° angles, whereas metal-Nimetal triplets tend to collinear positions, without appreciable changes in the nearest neighbour distances. These tendencies, different for Pd and Ni, are also reflected in the medium-range ordering features.