Heterogeneous microstructure enables a synergy of strength, ductility and electrical conductivity in copper alloys

Copper alloys that simultaneously possess excellent electrical conductivity, high strength and reasonable ductility are increasingly needed in aerospace, transportation and electronics industries. Unfortunately, these properties are usually mutually exclusive. Here, a strategy basing on constructing heterogeneous microstructures is proposed to overcome the above trade-off. Heterostructured Cu-Cr-Zr alloys, with micrometer-scale pure copper grains embedded inside a matrix of ultrafine copper grains with nanoscale precipitates are prepared via powder metallurgy. They show a high ultimate tensile strength of 458 MPa, which is higher than the prediction basing on rule of mixtures, meanwhile, retain a considerable ductility of 11% uniform elongation and an excellent electrical conductivity of 83.15% IACS. We further carried out loading-unloading-reloading tests and detailed microstructure characterizations to reveal the strain hardening mechanism induced by such heterogeneous microstructure. Our strategy indicates a promising route to achieve remarkable strength-conductivity-ductility synergy for copper alloys.