UN-BUNDLED CARBON NANOTUBES REINFORCED TITANIUM COMPOSITES VIA POWDER METALLURGY PROCESS

By using pure titanium powder coated with un-bundled multi-wall carbon nanotubes (MWCNTs) via wet process, powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with the CNTs was prepared by spark plasma sintering (SPS) and subsequently hot extrusion process. The microstructure and mechanical properties of P/M pure titanium and reinforced with CNTs were evaluated. The distribution of CNTs and in-situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyzer. The mechanical properties of TMC were significantly improved by the addition of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.46 mass%, the increase of tensile strength and yield stress of the extruded TMC were 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of tensile specimens were analyzed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed.