Laser welding of SiCp/2024Al composites with novel TiB2/2024Al composite filler

The effect of TiB2/2024Al filler on the microstructure and mechanical properties of SiCp/2024Al joint was investigated in this paper. The results indicated that needle-like Al4C3 phase with a content of 18.9% was the dominant precipitate in the weld zone (WZ) of direct welded (DWed) joint, which weakened the tensile strength (109.3 MPa) of DWed joint. The introduction of TiB2/2024Al filler changed the microstructure of WZ. In the molten pool, TiC precipitate was precipitated preferentially due to the higher chemical affinity of Ti and C atoms and lower Gibbs free energy of TiC formation. The dispersed TiC blocks presented strong fine grain strengthening and precipitation strengthening effects. Compared with DWed joint, the strength of SiCp/2024Al joint with TiB2/2024Al filler increased to 268 MPa, approximately 72.9% of that of base metal (BM).