Effect of Zn interlayer addition on the quality of laser brazed seam for CNTs/6N01Al composites

Objective The aim was to address the issues of poor joint formation, brittle phase generation, and severe thermal damage during the laser welding of CNTs/6N01Al composites. Methods Zn interlayers with varying thicknesses were introduced during the laser welding process, and the effects of Zn addition on the weld formation, microstructure, and mechanical properties of the CNTs/6N01Al composites were systematically investigated. Results The amount of Zn addition significantly affected the weld quality. A 0.05 mm Zn interlayer effectively enhanced molten pool fluidity, suppressed porosity defects, and reduced thermal damage to the base material. Consequently, the tensile strength of the joint reached 280.19 MPa, exceeding 70% of the base material’s strength. In addition, Zn evaporation reduced the welding heat input and inhibited the growth of the Al₄C₃ brittle phase. However, when the Zn thickness exceeded 0.10 mm, intense evaporation led to molten pool spatter and weld sagging. Conclusion An appropriate Zn interlayer can improve the formation quality of laser-brazed CNTs/6N01Al composite joints, suppress harmful metallurgical reactions, and reduce thermal damage. Conversely, excessive Zn causes weld formation instability and deteriorates joint performance. This study provides a process basis for the high-quality joining of CNT-reinforced aluminum matrix composites.