Cu‐Induced Self‐Adaptive Crystallization and Interfacial Stabilization in Cr 2 AlC Coatings for Advanced Electrical Contact Applications

ABSTRACT Electrical contact materials for advanced power transmission and electromagnetic systems must simultaneously provide high electrical conductivity, arc‐erosion resistance, and tribological stability under extreme electro‐thermo‐mechanical conditions. Herein, Cr 2 AlC and Cu‐doped Cr 2 AlC (Cr 2 AlC‐Cu) coatings were deposited on 7075 aluminum alloy via hybrid arc‐magnetron sputtering followed by low‐temperature annealing at 400°C. With increasing Cu content (0‐9.1 at.%), the coating microstructure evolves from single‐phase Cr 2 AlC to a dual‐phase architecture consisting of Cr 2 AlC and Al 4 Cu 9 . All coatings exhibit high hardness values (18.8‐21.2 GPa), originating from grain refinement and amorphous‐nanocrystalline structures induced by low‐temperature annealing. The Cu‐rich coating demonstrates the lowest electrical resistivity (119 µΩ·cm) and superior resistance to arc erosion. This performance enhancement is attributed to Cu‐assisted Al‐Cu interdiffusion, which accelerates in situ MAX‐phase crystallization and promotes the formation of conductive interfacial networks under Joule heating, establishing a positive feedback mechanism that stabilizes electrical transport and suppresses arc erosion. Moreover, the formation of an adherent Cu transfer layer transforms the frictional interface into a Cu‐Cu sliding contact, effectively reducing friction and preventing adhesive wear of the aluminum substrate. These synergistic effects activate a self‐adaptive crystallization and lubrication mechanism during service, highlighting Cu‐doped Cr 2 AlC coatings as promising candidates for next‐generation electrical contact applications.