Weld appearance and microstructural characteristics of friction stir butt barrier welded joints of aluminium alloy to copper

摘要

Friction stir butt barrier welding, an improved method based on the friction stir butt weldingnprocess, in which a barrier was configured on the butt plate, was applied to the Cu–Alncombination. The resultant Cu–Al joints presented good appearance when Al was adopted as thenbarrier. The pin shifting towards the Al side could improve the interior quality of the weld.nHowever, the effect was limited when the pin offset increased to a certain value. As the toolnrotation rate increased, the amount and size of the voids decreased first and then increased.nThere were two types of joint depending on the interfacial morphology: the smooth interface andnthe chaotic interface. When the pin offset was zero, the interface was occupied by large Cunfragments. As the pin offset increased, the joint interface transited first to the smooth type andnthen to the chaotic type. As the rotation rate increased, the laminate density around the interfacendecreased, and the sublayers in the laminates thinned.