摘要
In our study,the composition-dependent effects of atomic displacementsin Au-Cu-Ni-Pd-Pt basedalloys,comprising elements with large differences in atomic radii,are investigated at the atomic scale.Two alloys-the equimolar AuCuNiPdPt and AuCuNiPd-have been characterized using multi-edge extended X-ray absorption fine structure(EXAFS)spectroscopy in conjunction with reverse Monte Carlo(RMC)simulations at room temperature.The statistically-averaged component-dependent pair distribution functions(PDFs),which represent the distribution of atoms around the assumed regular face-centered cubic(fcc)lattice positions,reveal a shift of their peaks to shorter distances and a pronounced asymmetry in atomic distribution only for atoms with small radi(Cu/Ni).The analysis demonstrates that small atoms(Cu/Ni)are significantly more displaced from the expected lattice positions as compared to large atoms(Au/Pt).Furthermore,there are indications of preferential next-neighbour bonding that changes depending on the alloy composition.The most pronounced changes in the PDFs were found solely for Pd.With this study,we provide a basis for a deeper understanding of the composition-dependent atomic arrangement in chemically complex solid solutions.
