Enhanced mechanical properties of in situ synthesized TiC/Ti composites by pulsed laser directed energy deposition

Abstract

Titanium matrix composites (TMCs) have attracted extensive attention of researchers due to their excellent properties. However, the strength and ductility of TMCs hardly co-exist and show a trade-off between each other. To overcome the problem, in this study, with feeding the commerically pure titanium (CP–Ti) powder decorated by nano carbon, TiC reinforced Ti matrix composites were synthesized in situ by Pulsed Laser Directed Energy Deposition (PLDED). As the C content increases, the size, content and morphology of the TiC particles gradually change and the irregular block α phase transform to lath α phase in the matrix. As for Ti+0.6 wt% C, due to the strengthening effect of dispersed eutectic TiC and the evolution of morphology of α phase in the matrix, the ultimate tensile strength of TiC/Ti composites (940 MPa) is ∼84.3% and ∼108.9% higher than that of the PLDED and forged CP-Ti respectively, while retaining excellent elongation to failure (18.9%), which effectively solves the problem of strong-plastic contradiction existing in the preparation of TMCs. And at this carbon content, the friction and wear properties of the composites are effectively improved, the friction coefficient (0.26) is 55% lower than that of CP-Ti (0.58) obtained under the same process. This work shows a great potential way to significantly improve the mechanical properties of titanium alloys.