Microstructural and Mechanical Properties of Titanium Matrix Composites Reinforced with Nano Carbon Materials via Powder Metallurgy Process

Abstract

Powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with multi-wall carbon nanotube (MWCNT) was prepared by spark plasma sintering (SPS) and hot extrusion process, where the powder surface was coated by un-bundled CNTs via wet 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 analyser. The mechanical properties of TMC were significantly improved by adding a small amount of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of specimens were analysed 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.