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Laser welding research improves quality of aluminium–copper joints

Engineers at TWI have developed laser welding procedures that greatly improve the quality of welds made between copper and aluminium.

Overcoming material conflicts

When welding most dissimilar metal combinations, a key challenge is the different metals’ chemical incompatibility, which typically leads to the formation of brittle intermetallic phases and, consequently, inadequate weld properties.

To counteract this issue, TWI developed approaches that minimise the formation of these brittle phases for overlap joints of high purity-copper (Cu) and aluminium (Al) thin sheets and plates (with thickness range from 1mm to 6mm).

Applications in vehicle manufacture

The automotive industry could benefit significantly from these developments, as it makes extensive use of Al and Cu in the construction of vehicle batteries. These metals have excellent thermal and electrical properties, which make them ideal for this application.

Individual cell terminals within batteries are connected using busbars, which, along with the terminals, are manufactured from Cu- and Al-based alloys. Consequently, there are numerous monometallic (ie Cu–Cu and Al–Al) and bimetallic (ie Cu–Al) butt and lap joints in a typical battery pack. Current joining solutions, including adhesive bonding and mechanical fastening, are limited in terms of both joint quality and process productivity.

Process development

To minimise the formation of the brittle intermetallic phase between the metals, TWI explored using high-welding-speed processes, which resulted in fast melt and solidification rates, limiting the mixing of metals and leading to significant improvements.

Through this experimentation, TWI has been able to introduce a reproducible procedure which can assist Industrial Members in equipment and process selection for the joining of Cu to Al alloy thin sheets and plates.

For more information, please email

Avatar Paola De Bono Section Manager – Laser and Sheet Processes

Paola De Bono joined TWI in 2007, as a Project Leader and, subsequently, Senior Project Leader in the Laser and Sheet Processes Group. She has a Master Degree in Chemical Engineering from the University of Palermo, in Italy, and studied to gain the status of Chartered Engineer with the Italian Engineering Association. Furthermore, Paola has undertaken an Engineering Doctorate in Birmingham University, focusing on laser welding of high reflective metals thin sheets (e.g. copper and aluminium). Paola has over 7 years of specific experience in laser processing for micro-scale applications, including welding of high reflective metals and dissimilar materials applications. Since 2016, she is Team manager in the Laser and Sheet Processes Group. Her current role involves operational management of the section, supporting the delivery of the section strategy, in line with TWI’s corporate plan. Paola has become a Section Manager in 2020.

For more information please email: