In-situ fabrication of Ti6Al4V-matrix composite with modulated mechanical properties

This study evaluated the in-situ fabrication of Ti6Al4V-matrix composites using the extrusion-based direct-write additive manufacturing technique. The influence of B 4 C proportion within the slurry formulations, coupled with the sintering parameters on the mechanical properties of the builds was evaluated. X-ray diffraction (XRD) analysis confirmed the formation of distinct TiC, TiB, and TiB 2 phases in builds sintered at 1250 °C. Hardness increased with the incorporation of B 4 C reinforcements for higher volume fractions and longer sintering times, and are attributed to the higher volume fraction of hard TiC, TiB, and TiB 2 phases formed which reinforce the matrix, with the highest hardness (458 ± 72 HV) achieved in 3 wt% B 4 C builds sintered for 2 h at 1250 °C with slow cooling. In contrast, the lowest hardness (176 ± 41 HV) was measured in 1.1 wt% B 4 C builds sintered for 5 min at 1250 °C with fast cooling. Meanwhile, the compressive properties showed a reverse trend, with 1.1 wt% B 4 C exhibiting a higher strength and plasticity, while the builds with 3 wt% B 4 C reinforcements showed a lower strength and negligible plasticity. The higher compressive strength at lower B 4 C volume fraction is due to a more uniform distribution of in-situ phases, minimizing stress concentrators and enabling efficient load transfer, whereas higher B 4 C volume fraction promotes localized phase aggregation, reducing load-bearing efficiency and restricting plastic deformation. This study demonstrates that by adjusting the proportion of B 4 C reinforcements and optimizing sintering time, Ti6Al4V-matrix composites with tailored mechanical properties can be fabricated in-situ .