The micro-joining of Al foil and Cu foil is crucial for various industrial applications, such as manufacturing power lithium-ion batteries packs for electric and hybrid vehicles. An ongoing challenge in this process is the unsatisfactory joint strength, attributed to crack susceptibility and poor joint ductility. This issue is primarily caused by the continuous formation of an intermetallic compounds (IMC) layer between Al foil and Cu foil. This study investigates the microstructure and mechanical properties of Al/Cu lapped joints using laser spiral spot welding technique with a continuous-wave (CW) fiber laser. The research explores the effects of keyhole and molten pool flow on joint morphology and microstructure evolution, linking these aspects to joint fracture behaviors. The results demonstrate that CW laser spiral spot welding achieves defect-free joints with excellent mechanical properties. The controlled formation of IMC, alternated with ductile phases, effectively restricts crack propagation, enhancing shear strength and ductility. Optimal welding parameters, such as a laser power of 450 W and welding speed of 350 mm/s, yield joints with a maximum shear strength of 138.2 MPa, which represents a significant improvement over previous spiral spot welded joints and highlights the potential of CW laser welding for efficient and high-strength Al/Cu metal foil joints.

中文翻译：

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具有高强度和延展性的铝箔和铜箔的激光微连接

铝箔和铜箔的微连接对于各种工业应用至关重要，例如制造用于电动和混合动力汽车的动力锂离子电池组。该过程中持续存在的挑战是由于裂纹敏感性和接头延展性差而导致接头强度不令人满意。这个问题主要是由于铝箔和铜箔之间金属间化合物（IMC）层的连续形成造成的。本研究利用连续波 (CW) 光纤激光器的激光螺旋点焊技术研究了 Al/Cu 搭接接头的微观结构和机械性能。该研究探讨了小孔和熔池流动对接头形态和微观结构演变的影响，将这些方面与接头断裂行为联系起来。结果表明，连续激光螺旋点焊实现了具有优异机械性能的无缺陷接头。IMC 的受控形成与延性相交替，有效限制裂纹扩展，提高剪切强度和延展性。最佳焊接参数，如激光功率为450 W、焊接速度为350 mm/s，屈服接头的最大剪切强度为138.2 MPa，这比以前的螺旋点焊接头有显着改进，凸显了连续激光的潜力用于高效、高强度铝/铜金属箔接头的焊接。