Linear friction welding of Al–Cu Part 2 – Interfacial characteristics

Abstract

Metallurgically bonded aluminium–copper assemblies are used as electrical transition pieces in high direct current bus systems to transmit electricity. The brittle, high electrical resistance intermetallics that tend to form at the interface between these two materials are problematic for the electrical conductivity and efficiency of the connector. The manufacture of such assemblies therefore requires low heat input during joining so as to minimise the extent of formation of the intermetallic phases. The application of linear friction welding (LFW), an emerging high energy density solid state joining technology, for this purpose limits the formation of the intermetallic phases and produces more promising interfacial characteristics. In this work, aluminium–copper assemblies with two different geometries, namely, laboratory scale and full scale (customised to actual industrial requirements) were produced by LFW. These were characterised using scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and energy dispersive spectrometry (EDS) to identify the phases at the interface. In order to simulate the in-service behaviour of the aluminium–copper assemblies manufactured by LFW, the laboratory scale samples were heat treated at 300°C. The evolution in the interfacial region was compared with that of post-service connectors produced by explosive welding (EW) and LFW.Les assemblages d’aluminium–cuivre à joint métallurgique sont utilisés comme pièces de transition…