Effect of Cu content on microstructure transformation and mechanical properties of Fe-Al dissimilar laser welded joints

•Higher Cu content was benefit to reducing δ-ferrite, and improving hardness of WS;•The microstructure at interface consisted of (Fe, Cu)2Al5 and (Fe, Cu) Al3 IMC with adding Cu;•Higher Cu content was benefit to decreasing the hardness and peak thickness of IMCs layer;•The shear tensile strength of the welded joint with 0.3 mm-thick Cu foil was higher than that of direct samples.