Plastic deformation of nanocrystalline Pd–Au alloys: On the interplay of grain boundary solute segregation, fault energies and grain size

Plastic deformation of nanocrystalline Pd–Au is studied by means of atomic-scale computer simulations. The distribution of solutes is equilibrated in model structures of different grain sizes and compositions using a combination of Monte Carlo and molecular dynamics methods. The resulting samples are deformed under uniaxial load. The role of grain boundary solute segregation is analyzed in detail by comparing chemically and structurally relaxed samples with model structures that were only structurally relaxed or reloaded. By analyzing dislocation activity, site occupancy, atomic free volume in the grain boundaries, stacking and twin fault densities, we make a connection between composition-dependent properties of the miscible alloy and the observed stress–strain behavior.

Research highlights► Mechanical properties of nanocrystalline miscible PdAu by MD simulations. ► Grain boundary relaxation controls the mechanical properties of nanocrystalline PdAu for various grain sizes. ► Intrinsic material parameters are of minor importance for the onset of plasticity in nanocrystalline PdAu.