Beta Titanium Alloys Produced from Titanium Hydride: Effect of Alloying Elements on Titanium Hydride Decomposition

Abstract

The use of titanium hydride as a raw material has been an attractive alternative for the production of titanium components produced by powder metallurgy, due to increased densification of Ti compacts, greater control of contamination and cost reduction of the raw materials. However, a significant amount of hydrogen that often remains on the samples could generate degradation of the mechanical properties. Therefore, understanding decomposition mechanisms is essential to promote the components’ long life. Several studies on titanium hydride (TiH2) decomposition have been developed; nevertheless, few studies focus on the effect of the alloying elements on the dehydrogenation process. In this work, the effects of the addition of different amounts of Fe (5 and 7 wt. %) and Nb (12, 25, and 40 wt. %) as alloying elements were evaluated in detail. Results suggest that α→β transformation of Ti occurs below 800 °C; β phase can be observed at lower temperature than the expected according to the phase diagram. It was found that β phase transformation could take place during the intermediate stage of dehydrogenation. A mechanism was proposed for the effect of allying elements on the dehydrogenation process.

Increasing the Adherence of Metallic Copper to the Surface of Titanium Hydride

“…The exact dimensions of the plates are difficult to determine, since they are tightly fused with the rods. Comparing the data obtained with the literature [15,17], it can be assumed that the aggregate-like relief is formed as a result of the adsorption of various titanium ions: Ti(OH)2 2+ and [Ti(H2O)6] 4+ . A micrograph with a view field of 1000 µm of modified spherical titanium hydride (Figure 4) The analysis of images of the microstructure of the surface of spherical titanium hydride granules modified under dynamic conditions at pH = 4-5 (Figure 4) showed that the surface of titanium hydride granules is completely covered with an adsorption layer with a pronounced aggregate-like relief.…”

“…The exact dimensions of the plates are difficult to determine, since they are tightly fused with the rods. Comparing the data obtained with the literature [15,17], it can be assumed that the aggregate-like relief is formed as a result of the adsorption of various titanium ions: Ti(OH) 2…”

“…The analysis of the available research in this direction [3,4,14] showed that the regulation of the conditions for the production (pressure and temperature conditions) of spherical titanium hydride granules does not solve the problem of the formation of surface microcracks. The most promising method is to "heal" microcracks by artificially creating a multi-barrier system of energy "traps" on the surface of the granule, which makes it possible to slow down the processes of thermal diffusion of hydrogen from the crystal lattice of titanium hydride at high temperatures and protect titanium from oxidation [5,[15][16][17][18][19][20][21][22][23][24][25].…”

Influence of processing parameters on dehydrogenation of TiH2 in the preparation of Ti–Nb: A review

“…Chirico et al. [ 69 ] confirmed this observation by demonstrating that the FCC structure of δ-TiH 2 could be preserved after the first dehydrogenation stage. In their study, TiH 2 was mechanically alloyed with Nb and Fe before being sintered at 10 °C/min to a temperature of 1250 °C TiH 2 dehydrogenated in four stages, which was similar to the findings of Liu et al.…”

Recent Development in Beta Titanium Alloys for Biomedical Applications

“…Generally, β-type Ti alloys are produced by solidification/casting [93]. Recently, Chirico et al [114] reported a method to produce β-type Ti alloys using titanium hydride as feedstock by powder metallurgy. Such a method enhances the densification of Ti compacts, gets better control of contamination, and reduces the cost of raw materials.…”