LAUSR

The 1-mm-thick Al to Cu friction stir welding is successfully performed at the tool offsets toward Al side ranging from 0 to 2 mm. With increasing tool offset, the phenomenon of material sticking to tool shoulder surface is restricted and the area of Al–Cu mixing zone is reduced progressively. As the tool offset is increased from 0 to 1 mm, the weld shows a variation of intermetallic phases from CuAl2 + Cu9Al4 to CuAl2 and exhibits a lowering in hardness and tensile properties. The 2-mm-offset weld without intermetallic phases discernible exhibits the highest hardness due to the thinness of Cu lamellar and Al-rich compound layers, and the joint featured by a failure at the relatively soft region adjacent to harder Al–Cu mixing zone in a ductile pattern shows the best tensile strength equivalent to 80% of that of the base material.