Fabricating TiB2/Al-Si Composites by Wire Arc Additive Manufacturing: A Flux-Cored Wire Approach

TiB2 was introduced through a self-developed Al-Si alloys flux-cored wire, and TiB2 reinforced Al-Si composites were successfully fabricated via wire arc additive manufacturing (WAAM). Subsequently, the comprehensive influence of TiB2 particles on the formation mechanism of pores, the evolution of grain structure, and mechanical properties was studied. The results demonstrated that pores originated from hydrogen in the molten pool and the air carried by the flux-cored wire, which migrated and aggregated in the molten pool and mainly concentrated near the fusion boundary. The incorporated TiB2 particles significantly modified solidification behavior, migrating to grain boundaries under the combined effects of force, where they simultaneously pinned boundaries and promoted heterogeneous nucleation. This dual effect refined grain structure and promoted equiaxed crystals throughout deposited layers. Compared with the Al-Si alloys sample, the TiB2/Al-Si composites sample strength increased to 182.67±1.53 MPa and 165±4.24 MPa in the horizontal and vertical directions, respectively. However, the elongation decreased to 10±0.57% and 4.88±1.05% in the horizontal and vertical directions, mainly due to the excessive pores. This study provides a viable WAAM strategy for fabricating Al matrix composites with controllable microstructure-property relationships.