Microstructure and Mechanical Properties of Ti-TiH2 Based Matrix Composites Reinforced with xTiB2 Particles Processed by Powder Metallurgy

Abstract

The structure changes, microstructure evolution, and mechanical properties during Powder Metallurgy (PM) through High Vacuum Sintering of a Ti-TiH2 matrix reinforced with Titanium Diboride (TiB2) particles were investigated. Composites were fabricated at 850, 1100, and 1300 °C. The strategy for the fabrication process was to use the PM route employing titanium hydride (TiH2) to reduce the consumption of Commercially Pure Titanium (CP-Ti). The structure of the composites was analyzed using X-Ray Diffraction (XRD), while Optical Microscopy (OM), and Field-Emission Scanning Electron Microscopy (FE-SEM) analysis were used to study the microstructure. Vickers microhardness and nanoindentation were performed to evaluate the elastoplastic and mechanical properties. According to the results, the unreinforced Ti-TiH2 sample presented higher sinter-ability, attaining relative density values of 93% with the higher sintering temperature. Composite samples showed TiB and TiB2 phases without the presence of any TiH2 residual phase. The highest mechanical properties were measured for reinforced samples with 30 vol.% of TiB2, sintered at 1300 °C, showing values of 509.29 HV and 4.94 GPa for microindentation Vickers and nanoindentation essays, respectively, which resulted in 8.5% higher than the values for the unreinforced sample. In addition, their H/Er and H3/Er2 ratios are higher than those of CP-Ti suggesting a better wear resistance of the Ti-TiH2 matrix-reinforced samples, combined with its mechanical properties makes it more suitable than CP-Ti for its potential in biomedical applications.