Outstanding ductility of dissimilar laser Al/steel spot joint using a high entropy alloy interlayer

Laser spot welding (LSW) technology was used for the joining of low carbon steel to AA5052 Al alloy using a FeCoNiCrMn equimolar high entropy alloys (HEAs) interlayer for the first time. The addition of the HEA interlayer promoted the formation of a Fe-rich Fe-Al IMC with less brittleness and hardness. It resulted in an increase of the joint fracture load from 963 N to 1473 N and a dramatic improvement of the displacement increased from 0.66 mm to 3.32 mm. Another reason for the outstanding ductility of the dissimilar laser joint was the formation of a conical fusion zone in the joint, which realized the dual coupling of metallurgical bonding and mechanical interlocking at the interface.