Exploring the application of laser thermal effect in the multilayer gradient coatings designed by electrochemical deposition: Parameters, advancements, and limitations

This study presents an innovative approach distinct from conventional electrochemical deposition (ECD) techniques to produce multilayer gradient Fe-Ni coatings. This process incorporates the effective integration of laser energy fields, and the detailed thermal impact was extensively analyzed. The correlation between laser effects on the ECD process, element content, and microstructure was verified from the perspective of thermal effects. Even without altering the original face-centered cubic structure, the introduction of lasers significantly affects the distribution of element content and grain size. Therefore, this study presents two new laser-ECD processes that enable the fabrication of multilayer gradient structures. One approach involves obtaining a multilayer structure with alternating element content along the cross-section, from bottom to top. This is achieved by periodically varying current densities generated by continuously alternating thermal gradients formed through laser scanning. The second method aims to create a gradient structure prepared by adjusting the laser parameters that vary laterally or longitudinally along the substrate. Furthermore, the effectiveness of the gradient performance was demonstrated by revealing microstructure evolution and testing the microhardness. Finally, the advantages and limitations of laser thermal effects in preparing multilayer gradient structures are summarized.