A nanolaminated structure design to produce high-strength Cu alloys with enhanced electrical conductivity and thermal stability

Abstract

Nanocrystalline Cu has the merit of high strength but usually suffer from poor electrical conductivity and rapid grain coarsening, limiting its practical application. Here, we demonstrate that this challenge can be overcome by architecting a unique nanolaminated grain structure (NGS) with an ultra-thin lamellae boundary spacing of ∼55 nm, featuring pronounced Ag atoms segregation at high angle lamellae boundaries and very few defects inside the lamellae interiors, in a Cu-5wt.%Ag alloy. Benefiting from the synergistic contributions from the NGS, pronounced Ag atoms segregation at lamellae boundaries and continuous electron transport channels as well as a low electron scattering within the lamellae interiors, the resultant NGSed Cu-5wt.%Ag alloy achieves an ultrahigh tensile yield strength (YS) of 895 MPa, together with an excellent electrical conductivity of ∼83 % IACS (International Annealed Copper Standard) and a good thermal stability of 400 °C (∼0.4 Tm). The structure design strategy reported here, via nanolamellar grain structure combined with solute atoms decoration at lamellae boundaries, represents a promising approach that may be widely applicable to develop high strength, conductivity, and thermally stable nanostructured Cu-based materials for future structural and functional applications.