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

Abstract

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.