Manufacturing and performance assessment of in situ TiB/TiC-reinforced Beta 21S titanium matrix composites via B4C-assisted processing

This study addresses the manufacturing and performance assessment of in situ TiB/TiC-reinforced titanium matrix composites based on the commercial Beta 21S alloy. Composites were produced via B4C-assisted processing by arc melting Ti β21S with 0.5, 1.5, and 3.0 wt.% B4C powder additions, followed by solution treatment and water quenching. The effects of B4C content and water quenching on microstructural development and mechanical behavior were investigated through microstructural characterization, Vickers microhardness measurements, and compression tests performed at room temperature and at 150, 300, 600, and 900 °C. The addition of B4C promoted the in situ formation of TiB and TiC reinforcements within the titanium matrix, leading to improved hardness and compressive strength. Hall–Petch-type relationships were also determined to correlate grain refinement with mechanical response. The composite containing 3.0 wt.% B4C reached an ultimate compressive strength of approximately 1400 MPa and a compressive strain to failure of about 20%. At 600 °C, the B4C-assisted composites exhibited superior mechanical strength, above 500 MPa, compared with the unreinforced Beta 21S alloy, which remained below 300 MPa. Mechanical performance was further analyzed together with lightweight and economic aspects. Although the Ti + 3.0 wt.% B4C composite involves a relatively higher material cost, its specific strength of approximately 285 × 10³ m² s⁻² indicates an attractive cost-to-performance balance among the materials and composites considered. These results demonstrate that B4C-assisted processing is an effective route for producing in situ reinforced Beta 21S titanium matrix composites with promising high-temperature mechanical performance and lightweight engineering potential.