Investigation of resistance and intermetallic layer formation in laser-welded joints between Copper and AM Aluminium for electrical connections

Abstract

The increasing electrification of transportation demands the development of more energy-efficient solutions, where additive manufacturing (AM) of electrically conductive components presents new opportunities. The design flexibility of AM enables unique innovations; however, it also introduces challenges due to additional process parameters affecting part production. A key concern in the use of laser powder bed fusion of metal (PBF-LB/M) manufactured parts is their material properties, which are further influenced by part plane orientation during fabrication. Previous research has focused on copper -aluminum dissimilar welding, but the specific challenges posed by AM techniques have not been fully explored. This study investigates the welding behavior concerning resistance and intermetallic layer formation. Nickel -plated copper sheet metal samples were welded to AM aluminium samples using a continuous wave single -mode fiber laser with scanner optics in a lap joint configuration. Before welding, the interface surface of the AM samples was machined to exclude the surface roughness variance effect on the result. During the experiments, the welding's optical laser power was constant at 2kW and variations were made in welding speed ranging from 1200 mm/s to 400 mm/s in 200 mm/s increments. Electrical resistance measurements were taken using a high -precision micro resistance meter with a 4 -wire Kelvin testing method, also hardness testing, tensile testing, and energy dispersive spectroscopy (EDS) analysis were conducted. The results revealed that intermetallic compounds formed during welding, influencing joint properties. At a lower welding speed, more aluminium was mixed with copper which led to the weld solidification cracking. The optimum welding speed was between 800 and 1000 mm/s for this study test setup.