Improved wettability of Al-Si5 on DP980 steel during laser-induced heating by surface texture preparation

Sound wettability is the prerequisite for reliable joining of dissimilar metals. Surface textures prefabricating is a promising method to improve the surface properties of metals. Hence, surface textures with different line spacings were conducted on DP980 steel by nanosecond pulsed laser. This study investigated the laser-induced wetting behaviors of AlSi5 on surface processed DP980 steel substrates. The wettability of liquid AlSi5 presented anisotropy on textured surface, which was inhibited in perpendicular direction of the groove and promoted in parallel direction. Enhanced diffusion behavior and interfacial reaction were caused by surface textures. The absent Si-rich zone at triple lines (contact lines of solid-liquid-gas phase during wetting processes) of textured samples decreased the surface energy of droplets. Moreover, surface textures effectively reduced the normalized free energy, which provided greater driving force for spreading. However, the energy barriers caused by groove texture deteriorated the wettability in vertical direction. This method provided the possibility for the directional optimization of surface wettability, which laid the foundation for joining of dissimilar metals.