Impact of TiC particle size on the microstructural, mechanical, and tribological characteristics of the TiC/Ti6Al4V composites fabricated by concurrent wire-powder feeding laser direct energy deposition

Abstract Ti6Al4V alloys have prospective applications in advanced manufacturing of aerospace and chemical equipment. However, the sub-optimal hardness and wear resistance limit the service life of Ti6Al4V alloys under frictional wear conditions. To address this, Ti6Al4V alloy reinforced by micron-sized TiC particles (micro-TiC/Ti6Al4V) and hybrid micro-nano TiC ceramic reinforcements (micro/nano-TiC/Ti6Al4V) was prepared via concurrent wire-powder feeding laser direct energy deposition at a high TiC mass fraction (50 wt%). The influence of TiC particle size on the microstructure and tribological attributes of TiC/Ti6Al4V composites was investigated. The results demonstrate that for micro-TiC/Ti6Al4V composites, TiC appears primarily as equiaxial particles and coarse dendrites. On the contrary, hybrid micro–nano TiC ceramic reinforced composites feature dendritic TiC with distinct primary and secondary arms, as well as granular TiC, which is finer and more uniform. Moreover, the average diameter of α -Ti grains in micro/nano-TiC/Ti6Al4V is the least and has a pronounced positive influence on the composite’s mechanical characteristics. Ti6Al4V alloy has the highest UTS (913.3 MPa, 4.56% elongation), while TiC-reinforced composites show lower tensile properties and higher brittleness. While the fracture behavior of the Ti6Al4V alloy is primarily ductile in nature, micro-TiC/Ti6Al4V and micro/nano-TiC/Ti6Al4V composites mainly undergo quasi-cleavage fracture deformation. The micro/nano TiC/Ti6Al4V composite shows the highest microhardness of 509 HV among the tested materials. The wear resistance characteristics of the micro-TiC/Ti6Al4V composites and micro/nano-TiC/Ti6Al4V composites are superior in comparison to the unmodified Ti6Al4V alloy. Besides, among the two composites, the wear resistance of micro/nano-TiC/Ti6Al4V is higher.