Fabrication of a bimodal micro/nanoporous copper cladding layer by the high-speed laser cladding and dealloying

•Bimodal micro/nanoporous copper coating produced by laser cladding and dealloying.•0.1 M HCl solution was used for the preparation due to efficiency and controllability.•The optimal preparation time should be between 24–72 h. The Cu30Mn70 cladding layer was prepared by high-speed laser cladding technology and successfully combined with chemical dealloying method to prepare a bimodal micro/nanoporous copper coating. The 0.1 M HCl solution was experimentally determined as the dealloying solution. During the dealloying, the Mn-rich regions were preferentially corroded and formed micron pores in situ; the remaining regions served as a framework to form nanoporous structures on both sides. With increasing time, the transformation of the nanoporous structure led to micron ligaments thinning or fracture, resulting in the structural collapse of the bimodal microporous/nanoporous copper coating surface. Repeated oxidation-dissolution processes on the surface accelerate the structural collapse of the surface and inhibit the demanganization layer thickness growth. The same structure was formed in the cross-sectional direction, with no structural collapse due to continuous H+ consumption and low corrosivity in the micropores. The bimodal microporous/nanoporous copper coatings remained highly porosity and rapidly increased in thickness to 340 μm from 24 to 72 h. After 72 h, the surface structure started to collapse and the growth of the demanganization layer thickness slowed down.