Investigations of the microstructure and performance of TiCp/Ti6Al4V composites prepared by directed laser deposition

Abstract

This study focused on the effect of laser power on the macro-morphology, microstructure, bonding interface, and mechanical properties of 20 wt. % TiCp/Ti6Al4V titanium matrix composites (TMC). The unmelted TiC (UMT) gradually decreased, whereas the developed dendritic primary TiC and granular primary TiC increased by increasing the laser power. Laser power had no obvious effect on the texture of α-Ti, and α-Ti grains tended to be refined. The high laser power facilitated the melting of TiCp, thus, the maximum thickness of the C diffusion layer of UMT processed with 600 W was 6.1 μm. More interestingly, when low/high power deposition, some primary TiC and α-Ti had a specific orientation relationship, and high laser power was more conducive to the heterogeneous nucleation of Ti phase. The microhardness increased slowly, and TMC had higher tensile properties when the laser power varied in the range of 400-500 W.