Stability of ternary nanocrystalline alloys in the Pt–Pd–Au system

Abstract

Binary alloys have frequently been found to exhibit nanostructured states that are stabilized against grain growth when the minority alloying element strongly segregates to grain boundaries, thereby reducing the grain boundary excess energy. This concept has been formalized in several theoretical frameworks that are now used to design stable nanocrystalline binary alloys. In this work, we consider the extension of such a framework to ternary alloy systems. By considering pairwise interactions between atoms in ternary systems, we identify an experimental system, Pt–Au–Pd, and produce combinatorial alloy films in this system to evaluate their stability against grain growth. In several of these nanostructures stability against grain growth up to 400 °C is observed due to the co-segregation of Au and Pd solutes to the grain boundaries. This result is in line with calculations of a grain boundary energy-based estimation of stability after extending the analysis to account for the nontrivial ternary interaction.