Study on the bonding mechanism and performance optimization of Cu-12Sn-2Ni/42CrMo bimetallic interface controlled by Ag doping

This study employs DFT and experimental approaches to investigate Ag doping effects on Fe/Cu interfacial properties. Theoretical analysis shows that the negative formation energy of Ag at the Fe/Cu interface and its high work of adhesion confirm its thermodynamic spontaneity and the enhanced interfacial bonding capability. Experimental characterization reveals that 1 wt.% Ag addition effectively refines the Cu grain size due to the precipitation of fine Ag particles, which pin the grain boundaries and impede grain coarsening, while suppressing interfacial embrittlement via Ag segregation at the δ-Cu3Sn Sn phase boundaries. The optimal Ag concentration (1 wt.%) simultaneously increases the diffusion layer thickness from 2.85 μm to 6.49 μm and enhances the interfacial shear strength by 58.3%. Tribological evaluation shows that the optimal Ag doping level (1 wt.%) significantly improves wear resistance, whereas excessive Ag content leads to matrix softening and performance degradation. These findings provide a comprehensive understanding of Ag’s multiscale modification mechanism in Cu-12Sn-2Ni-xAg/42CrMo composites, linking atomic-scale interfacial bonding, microstructural evolution, and macroscopic mechanical properties, and offering valuable guidance for the design of high-performance metal composites.