Electrical breakdown and tribological properties of multicomponent surface alloys of stainless steel (SS)-Cu formed on Cu substrate with a low-energy high-current electron beam (LEHCEB) of microsecond duration are investigated. Formation of surface alloys is performed using deposition of SS films by means of magnetron sputtering followed by an LEHCEB liquid-phase mixing of the film and the top layer of substrate in a single vacuum cycle. A thickness of formed SS–Cu alloys is ranging within 1–10 $\mu{\rm m}$. Investigation of electrical breakdown of Cu electrodes with formed SS–Cu surface alloy showed almost three times increase in the high-voltage hold-off (1 MV/cm) compared with that for initial Cu electrodes (0.35 MV/cm). The gained high-voltage hold-off appears to be equal to that for electrodes made of SS and treated with an LEHCEB. Scratch tests revealed the significant improving adhesion of surface alloys to a substrate compared with that for the common magnetron-deposited coating of the same thickness.