A review on controlling the formation of intermetallic compounds in Ti/Al dissimilar metal laser weld seams

Titanium alloys and aluminum alloys are two lightweight alloys with a wide range of applications in aerospace and transportation. Ti/Al connectors combine the excellent properties of titanium alloys and aluminum alloys, which can markedly reduce the component weight and lower the cost. Laser welding has the advantages of high energy density, rapid heating concentration, short residence time at high temperatures. Therefore, it is considered to have unique advantages for joining Ti/Al dissimilar metals. However, due to the significant differences in the thermophysical properties and crystal microstructure of titanium and aluminum, it is highly probable that large residual stresses will be generated after welding. This can facilitate the formation and expansion of cracks. Meanwhile, titanium and aluminum are metallurgically incompatible systems due to their minimal mutual solubility at room temperature. The formation of brittle intermetallic compounds during the welding results in an increase in the brittleness of the joint, rendering it highly susceptible to fracture under stress. Consequently, the modulation of the formation of Ti/Al intermetallic compounds represents a pivotal approach to improving the quality of Ti/Al laser welded joints. In this paper, the current research status on the modulation of interfacial intermetallic compounds in Ti/Al laser welded joints is reviewed from three aspects: laser welding heat input, pre-weld pretreatment and post-weld heat treatment, and interlayer. Finally, on the basis of analyzing the existing problems in the current intermetallic compound modulation research, the future research and development direction of modulating intermetallic compounds in Ti/Al welded joints is proposed.