Mechanical Properties and Strengthening Mechanism of Pure Ti Powder Composite Material Reinforced with Carbon Nano Particles

Abstract

The strengthening mechanisms of titanium-carbon black (CB) nano particle composite materials were investigated quantitatively in the present study. The titanium matrix composite (TMC) specimens were prepared via a powder metallurgy (P/M) route including the wet coating process for composite titanium (Ti) powders with un-bundled CB nano particles, consolidation by spark plasma sintering (SPS) and subsequent hot extrusion. The extruded TMC, with carbon content of 2.66 at.%, exhibited excellent tensile strength of 837 MPa in 0.2%YS, 899 MPa in UTS and 18.7% in elongation at ambient temperature. In this composite, some of additive CB nano particles were dissolved into the Ti matrix as a solid solution element. The other CBs and Ti matrix were chemically reacted when sintering, and resulted in the in-situ formed titanium carbide (TiC) compounds, which were uniformly distributed throughout the Ti matrix. These TiC dispersoids promoted the dynamic recrystallization during hot extrusion process, and resulted in the Ti grain refinement. Consequently, carbon solid solution hardening, TiC dispersion strengthening and grain refinement enhanced the mechanical performance of the TMC. In particular, the effect of TiC reinforcements, accounting for about 60% of the whole strengthening behavior, played the most significant role.