The chemical ordering and local atomic pressures in icosahedral Au_NAl_(N-42)Ni₁₃ nanoalloys

Abstract The lowest energy chemical ordering configurations of 55 atom trimetallic Au N Al ( N −42) Ni 13 nanoalloys with Mackay icosahedron geometry were obtained through local relaxations performed using the Monte Carlo Basin-Hopping algorithm with the Gupta potential. This study explores how the chemical arrangement within an icosahedral structure influences the stability and mechanical properties of nanoalloys. In lowest energy structures, Ni atoms consistently occupy the icosahedral core, while Au and Al atoms stay on the surface, enhancing structural stability. Variations in mixing energy were evaluated to compare the relative stability of different compositions, with Au 17 Al 25 Ni 13 identified as having the lowest mixing energy at the Gupta level. Furthermore, the icosahedral core, composed entirely of Ni atoms, experiences strong compressive stresses, while surface atoms are subjected to different pressures depending on the atom type and occupation site. Specifically, Au atoms located on the surface experience both tensile and compressive stresses, whereas Al atoms undergo lowest tensile stresses.