Strength-ductility synergy in a hierarchical Cu-Cr-Zr alloy processed via laser powder bed fusion

Laser powder bed fusion (LPBF) is a promising method for manufacturing functional and structural integrated Cu-Cr-Zr components. However, the LPBF-processed Cu-Cr-Zr alloys still suffer from the strength-ductility trade-off dilemma, while maintaining high conductivity. Here, LPBF-processed Cu-Cr-Zr alloy with a hierarchical structure was obtained by increasing the Cr and Zr content simultaneously. After aging treatment, the hierarchical structure was composed of melt tracks at the macroscale, coarse grains (31.9 ± 0.1 μm) and fine grains (5.6 ± 0.2 μm) at the microscale, high-density of dislocations and dual precipitates at the nanoscale. The direct aged sample exhibited an excellent combination of strength and ductility (tensile strength was enhanced to 626 ± 1 MPa and uniform elongation of 16.2% ± 1.1%), which is superior to the traditionally wrought and LPBF-processed Cu-Cr-Zr alloys reported previously. Meantime, a good electrical conductivity of 71.1% ± 0.3% IACS was also achieved. In addition, the heterogeneous deformation-induced stress caused by the hierarchical structure not only led to a large increase in yield strength but also promoted tensile ductility.