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

Abstract

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 Al 3 Ti 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 Al 3 Ti 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 Al 3 Ti layer, and cracks tended to initiate there. The second phase strengthening of Al 3 Ti 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 %.