Tailoring network architecture via B4C addition in laser melting deposited (TiB+TiC)/TA15 composites for enhanced high-temperature tensile properties

: Titanium alloys face a notable strength–plasticity trade-off at elevated temperatures, limiting their use in high-temperature components. Although a network-structured reinforcement offers a promising solution, conventional fabrication methods often lead to reinforcement agglomeration, and precise control over network morphology remains challenging. In this study, (TiB+TiC)-reinforced TA15 titanium matrix composites (TMCs) with varied network architectures were fabricated via laser melting deposition (LMD) with different B 4 C additions. The influence of B 4 C content on the microstructure, network characteristics, and high-temperature tensile properties was systematically investigated. The results reveal that B 4 C addition triggers an in-situ reaction, forming a continuous (TiB+TiC) reinforcement network. At 3 wt.% B 4 C, this optimal network significantly enhances tensile strength to 876 MPa, representing a 34.98% improvement over the unreinforced TA15 through mechanisms including grain refinement, efficient load transfer, and crack propagation inhibition. However, excessive B 4 C (≥5 wt.%) causes agglomeration of reinforcements, which disrupts network continuity, degrades interfacial bonding, and induces brittle fracture, as evidenced by a drastic drop in ductility (1.32% elongation). This work identifies 3 wt.% B 4 C as the critical composition for maximizing high-temperature performance and establishes a viable additive-manufacturing-based strategy for designing network-architected titanium composites with balanced strength and structural integrity.