The influence of process parameters on the microstructure and properties of the TiC/Ti-alloy composites fabricated by the directed energy deposition process

In titanium matrix composites, the size and distribution of the reinforcing particles significantly impact their mechanical properties. Accordingly, in this work, TiC-reinforced Ti-alloy matrix composites were fabricated using the directed energy deposition (DED) technology. The influence of the varying process parameters on the microstructure and properties of the TiC-reinforcing particles and the α phase in the matrix was elucidated. The results revealed that process parameters had a notable influence on the morphology and distribution of the TiC reinforcing particles as well as the morphology of the α phase. A reduction in the pulse current and increasing scanning speed led to a significant decrease in the size of TiC reinforcing particles but offered uniform distribution. Concurrently, the morphology of the α phase changes from coarse lath-like to slender lath-like to irregular block-like. The combination of the TiC particles and the α phase with distinct characteristics resulted in significant variations in the room-temperature tensile properties of the TiC/Ti-alloy composites. The tensile strength of the TiC/Ti-alloy composites exhibiting optimal performance in this work reached 1412 MPa, which is ∼28% higher than that of the forged Ti-alloy matrix (1100 MPa). This research offers the groundwork for a substantial enhancement in the overall properties of titanium matrix composites.