Microstructure and mechanical properties of laser welded-brazed titanium/aluminum joints assisted by titanium mesh interlayer

This paper proposed a novel method of laser welding-brazing aluminum to titanium assisted by titanium mesh interlayer to further improve load capacity of Ti/Al joints. Experimental design method was used to study the effect of the titanium mesh on microstructure and mechanical properties of Ti/Al joints, and the specific process of Ti/Al interface reaction was revealed. The titanium mesh promoted spreading and wetting abilities of the molten aluminum on the titanium surface. Titanium dissolved into the molten aluminum and Al3Ti intermetallic compounds layer nucleated heterogeneously on the titanium surface during Ti/Al interface reaction. Compared with joints without titanium mesh, higher Ti element content and more Al3Ti particles were detected in the aluminum weld at joints with titanium mesh, which increased microhardness of the aluminum weld. High-density dislocations and low-angle grain boundaries were detected in the aluminum adjacent to the Al3Ti layer, and cracks tended to initiate there. The second phase strengthening of Al3Ti particles and larger connection area increased load capacity of the Ti/Al joints with titanium mesh. The optimal average tensile shear property of joints increased from 3.2 kN to 4.05 kN assisted by the titanium mesh, increasing by 26.6 %.