Abstract
Dissimilar metal joining techniques are necessary for the manufacturing of a number of structures and parts in the industries. The
spot welds of aluminium and copper were produced using two different tool geometries, different rotational speeds and tool
shoulder plunge depths. This paper presents the characterization of the intermetallic compounds using X-Ray diffraction (XRD)
and Energy Dispersive Spectroscopy (EDS) techniques in the Stir Zone (SZ). Furthermore, the microhardness test was performed
to investigate the effect of the intermetallics on the microhardness values. The XRD results showed that, the most common
intermetallic compounds formed in the spot weld samples were Al4Cu9, Al Cu3, Al2Cu3 and Al2Cu, which also showed low peaks
intensity. Moreover, the Energy Dispersive Spectroscopy (EDS) analysis also revealed the presence of intermetallic compounds
in the Stir Zone and which correlated to the X- ray diffraction analyses.
Higher microhardness values were obtained in the stir zone for all the welds due to the smaller grains present in this region
resulting from the frictional stirring of the tool. The high hardness values correlated to the high peaks of the intermetallics formed
at the interface.