Dynamic spreading and interfacial reactions during the laser-induced wetting process of aluminum on stainless steel

Due to the difference in heating time, temperature distribution and environment, it is insufficient to explain the interfacial behavior under non-isothermal conditions relying on the isothermal wetting mechanism. In this study, the laser-induced dynamic wetting process of stainless steel by Al alloy was investigated. The wetting behavior was recorded by a self-built experimental setup. The mechanism for the spreading and metallurgical evolution was revealed by numerical simulation, spreading dynamics analysis and thermodynamic calculation. With continuous laser irradiation, the dominant factor for spreading changed from reaction product to adsorption. Induced by the laser, a great temperature difference was generated at the center and front zone of the droplet. Si atoms accumulated toward the Fe substrate at a faster rate than Al atoms and different Si-containing compounds were generated depending on the satisfaction of atomic concentration conditions and energy conditions. The formation of the thin τ5-Fe2Al8Si phase near the triple line was considered to be a vital role in the maintenance of the spreading process. The laser process could be guided by this study to reduce the equivalent heat input, thereby controlling the type and thickness of the compound and obtaining predictable wetting.