Investigation on the two-stage hierarchical phase separation in the laser cladded Cu-Mn-Fe coating

A self-assembled Cu-Fe-Mn composite coating with a two-stage phase separation feature was prepared by laser cladding Cu and Mn mixed powders on a 316 L stainless steel plate. The hierarchical phase separation feature and structural evolution of the coating were systematically investigated. The microstructure of the coating exhibits by dendrites of (Fe, Mn)-rich phase and nanosized (Cu, Mn)-rich phase embedded within the matrix of the (Cu, Mn)-rich phase. During the cladding process, the micrometer-sized (Fe, Mn)-rich dendrites formed due to the primary separation, and then the nano-sized (Cu, Mn)-rich phase was further separated from the dendrites in the secondary separation process. Hierarchical porous structures were prepared by etching the Cu-Fe-Mn composite coating. This work provides an important insight into the structural evolution and etching mechanism of the laser cladded Cu-Fe-Mn composite coating.