L12-(Al,Si)3Ti+TiC hybrids reinforced laser welded SiCp/2A14Al joint with extraordinary strength

The interfacial reaction 3SiC + 4Al -+ Al4C3 + 3Si has bottlenecked the fusion welding of aluminum matrix composites for decades, hindering further improvement of the mechanical properties of high-strength lightweight SiCp/Al joints. Using unweldable SiCp/2xxxAl as an experimental model, we designed a targeted reinforcing phase that can be alloyed in situ with Si and C elements. L12-(Al,Si)3Ti and TiC were generated in situ from Si and C precipitated from SiC particles. In addition, the in situ-formed Al3Ti adhered to the surface of the SiC particles, enhancing the load transfer of the alloy film during the tensile process. The mechanism of titanium on the joint grain nucleation and refinement and the contribution of each strengthening mechanism to mechanical properties were discussed in detail. Quantitative calculations showed that the combined effects of the nanoscale TiC phase (Orowan strengthening) and high density of the geometrically necessary dislocations (dislocation strengthening) increase the yield strength of the joints. The ultimate tensile strength of the joint was 393 MPa (with a strength coefficient of 83%), which was highly comparable to that of SiCp/Al joints prepared by friction stir welding. This work provides fundamental guidance for the welding of high-strength SiCp/2xxxAl alloy.

Automated summary

By designing a reinforcing phase in unweldable SiCp/2xxxAl alloy, the mechanical properties of high-strength lightweight SiCp/Al joints can be improved. In situ generation of L12-(Al,Si)3Ti and TiC from Si and C precipitated from SiC particles, as well as the formation of Al3Ti on the surface of SiC particles, enhances load transfer and increases the yield strength of the joints through the combined effects of nanoscale TiC phase and high density of geometrically necessary dislocations.