Enhanced wear resistance of in-situ nanoscale TiC reinforced Ti composites fabricated by additive manufacturing

The poor wear resistance of Ti alloys limits its application in the orthopedic and dental surgery field. TiC as an ideal reinforcement phase can improve wear resistance due to its high hardness, low coefficient of friction, and good bio-compatibility. However, the wettability of the interface between the TiC and Ti matrix is poor, which leads to low mechanical properties and wear resistance. In situ TiC formed through the addition of a C source can enhance interfacial bonding. In this work, the Ti-graphite composites are prepared by Laser powder bed fusion (LPBF). On the one hand, the LPBF can prepare various complex porous shapes according to the personalized customized demand. On the other hand, the LPBF can provide a high cooling rate, suppressing grain growth and refining grains, and also can obtain equally distributed nanoscale TiC particles. The results show that the composites are mainly composed of Ti, TiC, and residual graphite. With the increase of graphite content, the amount of TiC increases and the grain becomes smaller, and the microhardness increases from 317 HV_0.2 to 408 HV_0.2. Meanwhile, the Ti-1.5 wt%Gr composite has a low friction coefficient, volume of wear, and wear rate, which is attributed to the high hardness of TiC particles and lubrication of graphite. The oxide on the surface of the wear mark is mainly composed of TiO₂ and TiO. The main wear mechanisms of the composites are oxidation wear and adhesive wear.