Microstructure and mechanical properties of (B₄C+TiC+TiB)/Ti6Al4V composites fabricated via laser melting deposition

To enhance the wear resistance and tensile properties of Ti6Al4V alloys, (B₄C+ TiC+TiB)-reinforced titanium-matrix composites (TMCs) were fabricated via laser melting deposition. Composites reinforced with 2% (TMC1), 5% (TMC2), and 10% (TMC3) B₄C powder (by volume) were developed. They consisted of α-Ti, β-Ti, undissolved B₄C, and in situ-formed (TiC+TiB) phases. TMC1 exhibited a network microstructure that disappeared as the B₄C content increased, resulting in a greater presence of undissolved B₄C particles and in situ ceramic phases. The Ti6Al4V matrix, used as a reference, exhibited an average microhardness of 352.79 HV_0.5 and a wear rate of 1.361 2×10^‒3 mm³/(N·m). In comparison, TMC1–TMC3 demonstrated progressively increasing microhardness values of 451.19 HV_0.5, 498.88 HV_0.5, and 541.13 HV_0.5, respectively, attributed to the increasing content of hard ceramic reinforcements. TMC1 and TMC2 also exhibited reduced wear rates of 7.892×10^‒4 and 6.513×10^‒4 mm³/(N·m), respectively, while TMC3 exhibited a higher wear rate (1.563×10^‒3 mm³/(N·m)) than the matrix, owing to secondary abrasion caused by particle detachment. Among the composites, TMC1 demonstrated the highest ultimate tensile strength of (1 246 ± 25.8) MPa, which exceeded that of the Ti6Al4V matrix by 14.49%, and an elongation of 0.9% ± 0.6%, which exceeded that of TMC2 and TMC3. The enhancement in mechanical performance was attributed to the synergistic effects of dispersion strengthening, grain-refinement strengthening, and solid-solution strengthening.