In-situ dissolution-reprecipitation of large TiC particles induced by high-power laser-arc hybrid additive manufacturing and the formation of hierarchical reinforcement architectures

In this study, a high-power laser-arc hybrid additive manufacturing process with synchronous powder feeding (LAHAM-SPF) was developed to fabricate TiC/Al-Cu composites. By optimizing the processing parameters, efficient introduction, stable deposition, and effective incorporation of TiC particles were achieved. On this basis, the evolution of TiC particles in the hybrid molten pool, the associated solidification behavior, and the resulting microstructure-property relationship were systematically investigated. The results showed that, under the high-power laser-arc hybrid thermal field, the initially added coarse TiC particles were evidenced to undergo partial dissolution and subsequent reprecipitation, leading to the formation of a multilevel strengthening architecture composed of retained coarse TiC particles, in-situ re-precipitated fine TiC p /TiC w and Al 3 (Ti,Zr) phases. This architecture significantly modified the solidification behavior of the hybrid molten pool, reduced the heterogeneous nucleation barrier of α-Al, and suppressed Cu segregation and the formation of a continuous grain-boundary θ-Al 2 Cu eutectic network. Owing to the synergistic effects of dislocation multiplication, grain refinement, Orowan strengthening, and load transfer, the ultimate tensile strength increased from 267.1 MPa for the Al-Cu matrix to 310.8 MPa for the composite. In addition, the wear resistance of the composites was markedly improved at both room and elevated temperatures, with the average wear rate reduced by approximately 88%-97%. These results suggest that LAHAM-SPF provides a new route for the high-quality fabrication of ceramic particle-reinforced Al composites and the construction of multilevel strengthening architectures, while also offering new insight into microstructural evolution and comprehensive performance regulation under hybrid heat-source conditions.