Investigation of phase transformation model, densification mechanism, and mechanical properties of TiH2 powder metallurgy materials.

TiH 2 has gradually gained attention in powder metallurgy because of its unique properties. This study systematically investigated the porosity, density, mechanical tensile properties, and fracture toughness of sintered samples of TiH 2 as a powder metallurgy starting material. The results showed that, compared with hydrogenation-dehydrogenation titanium (HDH Ti), the density, elongation, and fracture toughness of the sintered TiH 2 samples significantly improved. In addition, the contributions of grain size, porosity, and oxygen content to the yield strength of the samples are discussed, and the results revealed that a lower oxygen content and porosity are the main reasons for the differences in the mechanical properties between HDH Ti and TiH 2. Finally, the experimental results are combined with first-principles calculations and simulations to construct a TiH 2 phase transition model. The contribution of H atoms to the TiH 2 phase transition energy barrier and activation sintering densification was investigated and elucidated, revealing the TiH 2 sintering densification mechanism from the perspective of phase transition. The derived results contribute to a deeper understanding of the intrinsic mechanism of TiH 2 activation sintering densification, which is highly important for the development of advanced titanium materials. • The fracture toughness of TiH 2 sintered sample is higher than HDH Ti. • Lower yield strength of TiH 2 is attributed to grain size and oxygen content. • Higher density of TiH 2 sintered materials is related to grain growth. • H atom reduces TiH 2 phase transition barrier (δ →α). • Revealed the densification mechanism from the perspective of phase transition. [ABSTRACT FROM AUTHOR]