Dissimilar friction stir welding of Al to non-Al metallic materials: An overview

Tailoring of Dissimilar Friction Stir Lap Welding of Aluminum and Titanium

“…An essential problem, however, is the incompatibility of the thermal properties of these two metals, which significantly restricts the application of conventional fusion welding. Hence, innovative friction stir welding (FSW) is often considered as a possible candidate for the dissimilar joining of aluminum and titanium [ 1 , 2 , 3 ]. Being a solid-state technique, FSW avoids the formation of an undesirable solidification microstructure and, thus, enables the sound joining of various dissimilar materials.…”

“…Extensive research over the last two decades has conclusively demonstrated the feasibility of FSW for successive joining of aluminum and titanium alloys [ 1 , 2 , 3 ]. On the other hand, three important problems have been revealed.…”

“…One of the critical issues is the abrasion of the welding tool, which typically occurs during FSW of titanium alloys, e.g., [ 4 ]. To diminish this undesirable effect, high-cost tungsten-based tools are frequently used for dissimilar welding of aluminum and titanium [ 2 , 3 ].…”

“…The formation of intermetallic compounds at the aluminum–titanium interface is also of great concern [ 1 , 2 , 3 ]. Usually, intermetallic TiAl 3 has been reported to form [ 2 , 3 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ], presumably due to the comparatively low free energy of the intermetallic reaction in this case [ 20 ]. However, the details of this process are unclear.…”

“…However, the details of this process are unclear. In some cases, TiAl [ 3 , 6 , 7 , 9 , 10 , 15 ] and Ti 3 Al [ 2 , 3 , 6 , 21 ] phases have also been found. As shown by Choi et al [ 6 ], the development of TiAl and Ti 3 Al intermetallics is associated with a diffusion penetration of aluminum through the early-formed TiAl 3 phase.…”