Strengthening Mechanism of Powder Metallurgy Hot-Rolled Ti-Zr-TiC Composites

The microstructural and mechanical properties investigation on powder metallurgy (PM) Ti-Zr composite alloys dispersed with TiC particles via sintering and hot rolling process was carried out in this study. PM Ti-Zr-TiC composites were fabricated from the pre-mixed pure Ti, metal Zr and TiC powders, and heat treatment was applied to the sintered materials to homogenize Zr solid-solution in α-Ti matrix. XRD analysis results of these rolled composite materials indicated complete solid-solution of Zr elements. Microstructures observation clarified the binary Ti-(10-20%)Zr alloys had a mean grain size of around 4 µm, which was much smaller compered to pure Ti material with 10 µm grain diameter. According to the tensile test results, Ti-Zr alloys showed a remarkable increment of tensile strength due to Zr solid-solution and α-Ti grain refinement, and also had a large elongation. On the other hand, since Young’s modulus gradually decreased with increased in Zr content, TiC particles were added into Ti-10%Zr alloy to improve the modulus. The uniform dispersion of (2.5-5 wt%)TiC particles in the matrix resulted in the increase of both Young’s modulus and tensile strength. The experimental values of Young’s modulus showed a good agreement with the calculated one by using the law of mixture.