Study on the microstructural evolution and adhesion of copper coating on stainless steel foil during annealing

In this work, the nanoscale copper coating was successfully fabricated on the 301 stainless steel foil via direct current magnetron sputtering technology. The microstructural evolution and adhesion of copper coatings during annealing were analyzed, and the mechanical behavior and formability of the coated material were systematically studied. The results showed that the diffusion of both Fe and Cu elements at the interface remarkably increases with the increase in holding time, while interfacial bonding improves simultaneously. When the maximum holding time is up to 120 min, enhanced plasticity of the coated material can be achieved owing to the increased twin density, decreased geometrically necessary dislocation density, and preference orientation of Cu grains toward. Compared with the magnetron-sputtered material without annealing, prolonged annealing at 500 °C facilitates the elimination of columnar grains, increased elemental interdiffusion at the interface, and the formation of high-density twin boundaries, thereby enhancing the plasticity and adhesion of the coated material.