Effect of compaction pressure on the densification, microstructure and mechanical properties of Ti-1Al-8V-5Fe alloy based on TiH2 and HDH-Ti powders

The high-strength of Ti-1Al-8V-5Fe (Ti-185) alloy is due to TiH ₂ powders produced at different compaction pressures and compared with hydride–dehydride-Ti powders. The objective of this work was to investigate the microstructural evolution and mechanical properties of Ti-185 alloy under different compaction pressures. The dehydrogenation characteristics of TiH ₂ -185 and the oxygen contents of sintered samples were evaluated by thermogravimetric analysis and mass spectrometer (TG-MS) and oxygen/nitrogen (O/N) analysers. The corresponding microstructural evolution and change in mechanical properties were analysed by means of scanning electron microscopy, X-ray diffraction, electro-universal tester, and hardness tester, respectively. Results show that with the increase in compaction pressure, the green and sintered density and densification rates increase, but the volume fraction of α -phase decreases. The TiH ₂ -185 samples have higher densification and sintered density, lower oxygen content than Ti-185 samples, which is attributed to its better compressibility and superior self-cleaning ability as well as more water produced. In addition, the sintered TiH ₂ -185 samples exhibit higher yield strength and hardness in comparison with the sintered Ti-185 samples. The enhanced mechanical properties are attributed to its higher density and less soft α -phase in the microstructure.