Powder metallurgy titanium metal matrix composites reinforced with carbon nanotubes and graphite

Carbon nanotubes (VGCF) and graphite (Gr) reinforced Ti metal matrix composites (TiMMCs) were prepared via powder metallurgy. 0-0.4 wt% VGCF/Gr and Ti mixture powders were prepared by rocking mill. The as-premixed powders were consolidated at 1073 K using spark plasma sintering (SPS). Hot extrusion was performed at 1273 K with an extrusion ratio of 37:1. Microstructures and mechanical properties of the as-extruded Ti composites were investigated to evaluate strengthening effects of VGCF/Gr on Ti matrix. Mechanical strength of Ti-VGCF/Gr composites was augmented when VGCF/Gr contents were increased from 0.1 to 0.4 wt%. Yield strength (YS) and ultimate tensile strength (UTS) of Ti-0.4 wt% VGCF composites were increased 40.4% and 11.4% as compared to pure Ti, while those values were 30.5% and 2.1% for Ti-0.4 wt% Gr. The strengthening mechanism including grain refinement, carbon solid solution strengthening and TiC/carbon dispersion strengthening was discussed in detail.