Effect of Y-modified TiB2 ceramic particles on the microstructure and mechanical properties of TIG welded joints of spray-formed 7055 aluminum alloy

In this study, the Al–KBF4–K2TiF6–Y in situ reaction system was used to prepare rare earth (RE) element Y-modified TiB2 ceramic particles reinforced 7055 aluminum alloy welding consumables for inert gas shielded welding of spray-formed 7055 aluminum alloy. Compared with 0 Y- weld metal (WM), the grain size of the 0.1 Y-WM was refined from 30 μm to 25 μm. In the as-welded state, the tensile strength and elongation of 0 Y-7xxx and 0.1 Y-7xxx joints were 295 ± 6 MPa and 4.92 ± 0.24%, 327 ± 5 MPa and 6.45 ± 0.25%, respectively. The tensile strength and elongation of 0 Y-7xxx and 0.1 Y-7xxx joints after T6 heat treatment were 521 ± 5 MPa and 3.47 ± 0.24%, 557 ± 6 MPa and 4.84 ± 0.25%, respectively. The elongation of the 0.1Y-7xxx joint is 55.47% higher than that of the 0 Y-7xxx joint. The introduction of rare earth elements Y can improve the wettability of TiB2 particles and the substrate so that TiB2 particles are uniformly dispersed, and at the same time make TiB2 particles edge blunting, thereby improving the mechanical properties of welded joints.