Powder metallurgy Ti-TiC metal matrix composites prepared by in situ reactive processing of Ti-VGCFs system

Titanium metal matrix composites (TMCs) were fabricated via powder metallurgy (P/M) and hot extrusion. Planetary ball milling (PBM) was employed to disperse 0.4-1.0 wt% multiwall carbon nanotubes (VGCFs) with pure Ti powder. The fragmented VGCFs were found dispersing homogenously on the flaked Ti particles surface after PBMed for 24 h. The powder mixture was consolidated at 1073 K by the spark plasma sintering (SPS) process. Hot extrusion was performed at 1273 K with an extrusion ratio of 37:1. The microstructures and mechanical properties of the extruded Ti-VGCFs composites were investigated to evaluate the reactive processing of Ti-VGCFs system. The extruded Ti-VGCFs composites, with a 1.0 wt% VGCFs additive dispersed by PBM, exhibited an excellent tensile strength of 1182 MPa in 0.2% YS and 1179 MPa in UTS, which demonstrated a 143.6% and 80.7% increase compared to these of the extruded pure Ti, respectively. The strengthening mechanism was investigated and elucidated that the mechanical strength was attributed to the grain refinement and dispersion strengthening of the homogenously dispersed, in situ formed TiC particulates, as well as a solid solution strengthening of the carbon, oxygen and nitrogen elements in the Ti matrix.