Effect of intermediate layer Zn content on the quality of laser brazed joints for CNTs/6N01Al composites

Objective To address the poor joint formation, brittle phase formation and severe thermal damage during fusion welding of CNTs/6N01Al composites, Zn interlayers with different thicknesses were introduced into the laser welding process. Methods The effects of Zn addition on weld formation, microstructure and mechanical properties of CNTs/6N01Al composites were systematically investigated. Results Zn significantly improved weld quality. A 0.05 mm Zn interlayer enhanced molten pool fluidity, suppressed porosity defects, reduced thermal damage to the base material, and increased the tensile strength of the joint to 280.19 MPa, exceeding 70% of that of the base material. In addition, Zn evaporation reduced the welding heat input and inhibited the growth of the brittle Al₄C₃ phase. When the Zn thickness exceeds 0.10 mm, intense evaporation led to molten pool spattering and weld collapse. ConclusionAn appropriate Zn interlayer improved the formation quality of laser-welded CNTs/6N01Al composite joints, suppressed harmful metallurgical reactions and reduced thermal damage; however, excessive Zn caused weld formation instability and deteriorated joint performance. This study provides a process basis for the high-quality joining of CNT-reinforced aluminum matrix composites.