Enhanced combination of mechanical and electrical properties of a Cu-Cr-Zr alloy by optimized two-step thermomechanical treatment

A high-performance Cu-Cr-Zr alloy, including ultimate tensile strength of 669MPa, elongation to fracture of 15.7% and electrical conductivity of 73.1% IACS is achieved by the optimized two-step thermomechanical treatment. The microstructure of the alloy is characterized by the scanning electron microscopy equipped with electron-backscattered diffraction and transmission electron microscope. The results show that the second phases are precipitated sufficiently by the optimization of the process of primary aging treatment, causing an increase in electrical conductivity without deteriorating the mechanical properties. This optimized process is helpful to obtain the finer grains, higher density of dislocations, ultrafine and denser precipitates in the matrix. The uniformly distributed Cr precipitates with average size of 3.07nm are observed in the Cu matrix and have a strong pinning effect on the migration of grain boundaries and dislocations, resulting in an excellent combination between the mechanical and electrical properties in the Cu-Cr-Zr alloy. This work will provide a significant guideline for the fabrication of high-performance copper alloy through optimizing the thermomechanical process.