Elemental selection, microstructural tailoring, and amorphous formation in bimetallic nanoporous alloys via dealloying

Amorphous nanoporous alloys combine unique merits of metallic glasses with nanoscale architectures, making them highly attractive for catalysis, energy storage, sensors, and advanced structural applications. In this study, a series of monometallic and bimetallic nanoporous samples were fabricated via dealloying from designed Y₅₆NE₂₄Al₂₀ metallic glass precursors (where NE represents one or two noble elements, including Cu, Ag, Au, Pt, Pd, Ir, and Ru) in a 0.05 M H₂SO₄ solution. For the first time, a fully amorphous bimetallic nanoporous alloy was successfully fabricated via dealloying. The effects of the noble element combinations in the precursors on phase evolution (from amorphous to nanocrystalline) and morphological tailoring of the resulting nanoporous samples were investigated. The correlations between the growth rates of nanoporous layers, kinetic coarsening behaviors of ligaments and the dealloying conditions in these monometallic and bimetallic nanoporous samples were revealed. The critical parameters, i.e. the full width at half maximum ratio, coarsening exponent, and matching characteristics between the selected noble elements, were proposed to evaluate the amorphous-forming ability in nanoporous alloys. This study breaks through the conventional constraint of ordered atomic stacking during dealloying in simple alloy systems, and establishes a facile method for designing, fabricating and identifying nanoscale amorphous alloys.