Research on the microstructure and hardness and wear resistance of graphite-reinforced titanium matrix composites

To improve the wear resistance of titanium alloys, selective laser melting (SLM) was used to fabricate graphite-reinforced titanium matrix composites with graphite mass fractions of 0.5 weight percent (wt.%), 1.5 wt.%, and 3.0 wt.%. In these composites, titanium carbide (TiC) was formed in situ. Microhardness tests were conducted, wear parameters were quantitatively evaluated, and the strengthening mechanism contributing to wear resistance was analyzed. The results show that the microhardness of the composites increases steadily with increasing graphite content. The composite with 1.5 wt.% graphite exhibits the best wear resistance; compared with the 0.5 wt.% graphite sample, its volumetric material loss is reduced by 10.3%, and the wear rate is decreased by 10.8%. This improvement originates from the synergistic effect between in situ TiC particles and residual graphite. Fine-grained TiC enhances the matrix's deformation resistance through dispersion strengthening, while graphite forms a solid lubricating film at the friction interface, thereby reducing friction. Excessive graphite, however, leads to coarsening and spalling of TiC particles, which induces abrasive wear and deteriorates the wear resistance. This material can effectively reduce wear debris generated by medical implants, thereby lowering the risk of postoperative complications.