Directional enhancement of wettability for Al /stainless-steel system: Exploring the potential of laser-chemical hybrid surface texturing

With the development of manufacturing technology, microtexturing technology has become a promising way to improve the wettability of heterogeneous metals. In this study, a novel laser-chemical hybrid surface texturing (LCHST) approach was developed to enhance the wettability of the Al/stainless-steel (SS) system. A modified sessile drop method was used to investigate the wetting behavior at high temperature of 4043Al on 301L SS with various groove spacings. The dynamic process was captured simultaneously from two orthogonal directions. The spreading mechanism was revealed by comprehensive analysis of surface characterization, microstructure identification of precursor film, and spreading kinetics. LCHST increased the specific surface area and changed the composition of the oxide film, resulting in higher surface energy with smaller groove spacing and enhanced wettability. The spreading process was driven by the capillary force, which relied on the subcutaneous infiltration mechanism that formed a precursor film of (Fe,Cr)Al 3 and (Fe,Cr) 2 Al 5 . The spreading kinetic analysis revealed that LCHST reduced the spreading activation energy in the parallel direction and increased it in the perpendicular direction, resulting in anisotropic wetting spreading. The new approach and the underlying spreading mechanism could offer new insights into the directional enhancement of the wettability of the Al /SS system.