Welding Optimization of Dissimilar Copper-Aluminum Thin Sheets with High Brightness Lasers

Dissimilar welding of Al and Cu represents a big challenge due to the formation of brittle intermetallic phases. The present study is focused on the laser beam welding optimization of Al-Cu thin sheets using high brightness lasers. Joints were produced with welding speeds as fast as 12 m/min, characterized both mechanically and electrically, with microstructure analysis. The results exhibit that when Al is on top of Cu, the weld volume is large and several microcracks show up due to the formation of CuAl₂ (θ), CuAl (η₂) and Cu₉Al₄ (α) phases. When Cu is on top of Al instead, the weld volume is small and just CuAl₂ (θ) phase is formed; no cracks are observed. This behavior is explained through the correlation between the weld volume, the different interaction of Al and Cu with the laser beam and the intermetallic phases generated in the weld.