Ultrastrong spinodoid alloys enabled by electrochemical dealloying and refilling.

We present an extreme case of composition-modulated nanomaterial formed by selective etching (dealloying) and electrochemical refilling. The product is a coarse-grain polycrystal consisting of two interwoven nanophases, with identical crystal structures and a cube-on-cube relationship, separated by smoothly curved semicoherent interfaces with high-density misfit dislocations. This material resembles spinodal alloys structurally, but its synthesis and composition modulation are spinodal-independent. Our Cu/Au "spinodoid" alloy demonstrates superior mechanical properties such as near-theoretical strength and single-phase-like behavior, owing to its fine composition modulation, large-scale coherence of crystal lattice, and smoothly shaped three-dimensional (3D) interface morphology. As a unique extension of spinodal alloy, the spinodoid alloy reported here reveals a number of possibilities to modulate the material's structure and composition down to the nanoscale, such that further improved properties unmatchable by conventional materials can be achieved.