In-Depth Evaluation of Ultrasonically Welded Al/Cu Joint: Plastic Deformation, Microstructural Evolution, and...

Area of Science:

• Materials Science
• Manufacturing Engineering
• Energy Storage Technology

Background:

• Ultrasonic metal welding (USMW) is crucial for assembling lithium-ion (Li-ion) battery packs, enabling solid-state joining of dissimilar conductive materials.
• A clear understanding of the USMW process and its underlying mechanisms is still needed for optimization.

Purpose of the Study:

• To investigate the dissimilar welding of aluminum alloy EN AW 1050 to copper alloy EN CW 008A using USMW.
• To simulate tab-to-bus bar interconnects for Li-ion battery assembly.
• To analyze the effects of plastic deformation and microstructural evolution on mechanical properties.

Main Methods:

• Dissimilar welding of Al/Cu using Ultrasonic Metal Welding (USMW).
• Qualitative and quantitative analysis of plastic deformation and microstructural evolution.
• Tensile shear testing to evaluate mechanical performance of the joints.

Main Results:

• Plastic deformation during USMW was concentrated on the aluminum side, with over 30% thickness reduction.
• Complex dynamic recrystallization and grain growth were observed near the weld interface.
• Tensile shear test results showed that failure load increased with welding duration up to 400 ms, then plateaued.

Conclusions:

• Mechanical properties of Al/Cu joints are significantly influenced by plastic deformation and microstructure evolution during USMW.
• The findings provide valuable guidance for enhancing weld quality and optimizing the USMW process for battery applications.