Investigation of strengthening mechanisms and conductive behavior of Cu-Ni-Co-Si alloys based on first-principles calculations and experimental verification

Cu-Ni-Co-Si alloys are promising materials for advanced electronic applications; however, simultaneously improving their mechanical strength and electrical conductivity remains challenging. This study combines first-principles calculations with multiscale experiments to investigate the microstructural evolution and electrical transport behavior of a Cu–Ni–Co–Si alloy. DFT calculations demonstrate that Si-induced s-p hybridization and directional covalent bonding significantly enhance the elastic modulus of the Cu matrix. Solute Co atoms are identified as the primary source of carrier scattering due to deep local potential wells; their precipitation during aging reduces the residual solute content in the matrix, thereby improving electrical conductivity. Experimentally, the alloy aged at 400 ℃ for 6 h achieved a peak ultimate tensile strength (UTS) of 1015 MPa and an electrical conductivity of 50.3% IACS. Microstructural characterization reveals that specific alloying elements lower the intrinsic stacking fault energy (SFE), promoting a transition from dislocation slip to twinning-induced dynamic Hall-Petch strengthening. Quantitative analysis confirms that the Orowan bypassing mechanism by dispersed nanoscale Ni₂Si and Co₂Si precipitates provides the dominant strengthening contribution at the peak-aged state. This study establishes a multiscale correlation between electronic structure and macroscopic properties, providing a theoretical framework for the design of high-performance copper alloys.