A dual heterogeneous laminated microstructure design for improving the mechanical properties and electrical conductivity of copper alloys

Achieving an excellent combination of mechanical properties and electrical conductivity in conductive copper alloys is highly desirable but remains a great challenge. This paper reports a dual heterogeneous laminated (DHLed) Cu/Cu-Cr-Zr composite structure in copper alloys produced by accumulative roll bonding (ARB) and annealing process that can produce an excellent property combination: high strength (ultimate tensile strength: 563.4 ± 14 MPa), sufficient tensile ductility (uniform elongation: ~16.2%), and high conductivity (~92%IACS). The specially designed DHLed Cu/Cu-Cr-Zr composite microstructure is characterized by alternating coarse- and ultra-fine grain layers and layered distribution of precipitations. Such dramatic microstructure heterogeneities produce significant hetero-deformation induced hardening due to mechanical incompatibility between soft Cu and hard Cu-Cr-Zr layers, which leads to an excellent combination of strength and ductility. The high conductivity can be attributed to the unique DHLed Cu/Cu-Cr-Zr composite structure containing alternating recrystallized- and nanolaminated-grain layers.