Effect of tungsten mesh interlayer on microstructure and mechanical performance of A6061/Ti6Al4V dissimilar joints

Highlights: • Al3(Ti,W) layer was formed at Ti/Al interface due to segregation of the W element. • D022-Al3(Ti,W) was transformed into L12-Al3(Ti,W) as the W content increasing. • Toughness of the brittle Al₃Ti layer formed at Ti/Al interface was increased. • Spreading abilities of molten aluminum were enhanced by tungsten mesh. • Tensile shear property of Ti/Al joints was enhanced using tungsten mesh interlayer. A novel method of laser welding-brazing A6061/Ti6Al4V with the assistance of a tungsten mesh interlayer was proposed. The spreading and wetting abilities of the molten aluminum on the Ti6Al4V surface were improved by the addition of the tungsten mesh. Al₅(Ti, W) and Al₁₈Mg₃W₂ were observed as second phases in the aluminum weld, which was a benefit to refine the aluminum grains and improve the mechanical properties of the aluminum weld. The Al₃(Ti, W) layer and the (Al, Si)₃Ti layer were observed at the Ti/Al interface. W and Si atoms substituted Ti and Al atoms in Al₃Ti, respectively. W element distributed unevenly in the Al₃(Ti, W) layer and segregated at the grain boundaries of the Al₃(Ti, W) phases. D0₂₂-Al₃(Ti, W) was transformed into L1₂-Al₃(Ti, W) at the grain boundaries resulting from the segregation. The c/a value of the (Al, Si)₃Ti crystal lattice was higher than that of Al₃Ti. Nanohardness and elastic modulus of the (Al, Si)₃Ti phase were higher than those of the Al₃(Ti, W) phase. The tensile shear capacity and ductility of the A6061/Ti6Al4V joints with tungsten mesh were better than those of the joints without tungsten mesh at the same welding parameters.