Stable cladding of high reflectivity pure copper on the aluminum alloy substrate by an infrared-blue hybrid laser

Abstract

• A coaxial infrared-blue hybrid laser was adopted in cladding pure copper on the AlSi7M-g alloy substrate, which can make up for the forming instability of infrared laser and blue laser. • Hybrid laser can bring about a larger molten pool size, a slower cooling rate and a coarser microstructure. • The improvement in cladding stability under hybrid laser is closely related to the great increase in total laser absorption rate of the high reflectivity alloy and the reduction in fluctuation of absorption rate. A coaxial infrared-blue hybrid laser system was adopted in the cladding of high reflectivity pure copper on an AlSi7Mg alloy substrate, and the cladding stability, molten pool size and microstructure of the cladded samples by three types of laser sources (infrared, blue and their hybrid sources) were compared. The infrared-blue hybrid laser was validated to compensate for the forming instability of a high-power infrared laser and a low-power density blue laser. In addition, the heat accumulation in the cladding process with the hybrid laser was more obvious and the cooling rate was slower (1.36 × 10 4 K/s), which led to a coarser microstructure (1.56∼2.42 μm). Therefore, the hybrid laser can bring about stability and a larger molten pool size in cladding pure copper on the aluminum substrate, which is closely related to the great increase in the total laser absorption rate of the high reflectivity alloy and the reduction in the fluctuation of the absorption rate.