Achieving strength-ductility synergy in Au-Pt alloys through systematic screening of alloying elements: First-principles insights

The intrinsically low strength of Au-Pt alloys remains a key obstacle to their wider use in advanced applications requiring high mechanical reliability and service durability. To address this issue, we employ first-principles calculations to systematically evaluate the effects of diverse alloying elements on their mechanical properties, aiming to identify promising candidates for alloy design. A combined analysis of solid-solution strengthening and slip barrier reveals that Re and Os, located near the boundary between the high-melting transition and platinum-group metals, together with rare-earth element Ce, exhibit an outstanding strength-ductility synergy. Notably, the strengthening induced by high-melting transition additions is primarily governed by chemical interactions, whereas lattice distortion arising from volume misfit dominates for most other solutes. Ce delivers the strongest solid-solution strengthening due to its largest size mismatch. Electronic structure analyses further reveal that solid-solution strengthening originates from the injection of additional valence electrons. Meanwhile, Ce uniquely reduces the slip barrier by weakening the local bonding character in the vicinity of the Fermi level, thereby effectively preserving the intrinsic slip capability of the Au-Pt base alloy while markedly enhancing strength. Overall, this work provides a quantitative basis and mechanistic guidance for performance optimization and ternary-alloy design of Au-Pt alloys