Microstructure and Strengthening Mechanism of Powder Metallurgy Extruded Titanium Alloys with Carbon Solid Solution

The effect of carbon elements on the microstructures and mechanical properties of pure Ti alloys fabricated through extruded powder metallurgy route was investigated. Furthermore, the strengthening mechanism of the extruded materials was investigated quantitatively. In Ti-C materials, the lattice parameter in c-axis of α-Ti increased due to solid solution of carbon atoms in the most stable octahedral interstitial sites. As the carbon contents increased, tensile strength was increased while maintaining a high elongation at break. The 0.2% yield stress of Ti-2.0 mass% TiC increased by 242 MPa compared with that of pure Ti. The elongation at break exceeded 35.0% for all specimens. According to this analysis, it was clarified that Fm value of Ti-C materials was 2.90×10-10 by using Labusch model. The estimated strengthening improvement using these values was significantly agreed with the experimental results of PM Ti alloys with carbon solution atoms. Furthermore, the strengthening mechanism of the alloys was quantitatively clarified that carbon solution strengthening was the dominant factor in this study.