Thin overgrowths of nickel were epitaxially formed by electrodeposition on substrate single crystals of copper having specific orientation and geometry. The prepared composite crystals were deformed in tension to small strains and found to have yield stresses significantly lower than for unplated copper crystals. Supported by evidence from replica‐electron microscopic examination of the surface slip structures, it is proposed that the elastic condition of the low interfacial misfit formed by the thin nickel overgrowth on copper promotes activation of surface dislocation sources.