Pressure effects on the structure and diffusion of liquid Zr50Cu25Al10Pd15 during rapid solidification: a molecular dynamics simulation study

The local structure of Zr50Cu25Al10Pd15 metallic liquid and glass under various pressures from 0 to 50 GPa during rapid solidification is evaluated using molecular dynamics simulations. The relation between structural change and the pressure is discussed in terms of distribution functions, local coordination, chemical short range, common neighbours and diffusion of atoms in the system. The results are in good agreement with other theoretical and experimental data given for the unloaded and pressurised system. The applied pressure up to 50 GPa has compressed the free volume in the system under consideration and shortened the neighbour distances. Although the clusters of ideal icosahedra and bcc order weaken and the fcc and hcp order develop with pressure, the system maintains the short-range arrangement of the icosahedra at all pressures studied here. It is seen that Zr50Cu25Al10Pd15 glass is characterised by Zr-centred Frank-Kasper polyhedra and Cu, Al- and Pd-centred ideal icosahedral clusters. It becomes clear that Pd and Zr are the atoms whose local arrangement is most affected by pressure due to change in their local coordination, chemical preference and diffusion.