Simultaneously enhancing erosion and compression resistance: designing AlCoCrFeNi high-entropy alloy strengthened Ag-based contacts

Designing microstructures and unveiling dynamic erosion mechanisms remain important challenges for Ag-based contacts. To simultaneously enhance erosion and compression resistance, an AlCoCrFeNi high-entropy alloy (HEA) is introduced into Ag-based materials to fabricate novel Ag-HEA contacts with island- and skeleton-restricted microstructures. The arc erosion experimental results reveal that the skeleton-restricted HEA microstructure is the key factor in reducing the hill and crater morphologies of the contact surface, effectively delaying material transfer between the movable and stationary contacts. The molten bridge evolution and compressive deformation behavior of Ag-HEA contacts with various microstructures are investigated using molecular dynamics (MD) simulations. MD results indicate that the constraint of Ag atom diffusion in the molten pool and the involvement of HEA atoms in the molten bridge are the primary mechanisms for improving erosion resistance. The skeleton-restricted HEA microstructure reduces the total energy and structural stability of the molten bridge system and promotes its fracture and disintegration. Moreover, the synergistic effect of the twin and Lomerz–Cottrell lock structures can hinder dislocation glide, generating dispersed and small-area stacking faults in the Ag matrix and mitigating the concentration of shear strains. Thus, the skeleton-restricted HEA microstructure contributes positively to compression resistance. This study presents a novel approach to designing Ag-based contacts. Graphical abstract