Electrical conductivity of AA1350 produced by additive manufacturing for electrical machine applications

Aluminium offers an attractive alternative to copper for high frequency electrical machines, with a lower cost and improved sustainability. Aluminium can perform as well as copper at high frequencies if implemented correctly, with a much lower mass. The geometrical freedom of Additive Manufacturing (AM) is enabling electrical machine windings with higher slot fill factors and improved heat and loss management which can yield machines with higher power density and efficiency, key enablers for the decarbonisation of transportation. However, aluminium alloys currently used in AM such as AlSi10Mg are generally unsuitable for electrical applications due to low conductivity of approximately 30% IACS. In this study AA1350 is processed with AM for the first time, demonstrating a conductivity of 53.3% IACS and 55.3% IACS in the as-built and heat-treated state respectively with a density of above 98%. AA1350 is shown to have limited orientation dependent conductivity due to microstructure, however, high surface roughness such as that on the downskin of overhung surfaces can have a detrimental impact on the perceived conductivity by reducing effective cross-sectional area. As demonstrated, AA1350 currently offers the highest conductivity of any aluminium alloy manufactured by AM and may be used directly in the as-built state if surface roughness is controlled in-process, thereby removing the need for heat-treatment.