Tailoring strength–ductility synergy in Cu–Ti–Fe alloys via Ni micro-alloying: A combined experimental and crystal plasticity study

To meet the stringent demands of the microelectronics industry for high strength and excellent plasticity in copper-based alloys, this study focuses on the Cu-1.6Ti-0.3Fe alloy system. By precisely controlling the Ni microalloying content (0.2, 0.5, 1.0 wt.%) and employing multiple techniques including SEM-EDS, EBSD, DIC, and CPFEM simulations. Results indicate that Ni uniformly solid-solves as a substitutional solute in the Cu matrix. It achieves synergistic enhancement of strength and ductility by refining grains (from 3.85 to 3.21 μm), optimizing texture (weakening Brass texture while strengthening Cube texture), and promoting dislocation proliferation and deformation twinning (from 1.07% to 1.67%): Tensile strength increased from 736.31 MPa to 892.66 MPa, hardness rose from 174 HV to 258 HV and elongation improved from 14.12% to 17.59%. The strengthening mechanism stems from the synergistic contribution of grain boundary strengthening (111.39 to 138.41 MPa) and dislocation strengthening (102.32 to 161.77 MPa). DIC and CPFEM simulations confirm more uniform strain distribution and coordinated slip system activation in the high-Ni alloy. This study elucidates the intrinsic mechanism by which Ni regulates the synergy between strength and ductility in Cu-Ti alloys, providing important reference for the design of high-performance copper alloys.