Atomic-scale investigation of hydrogen distribution in a Ti Mo alloy

Abstract

Ingress of hydrogen is often linked to catastrophic failure of Ti-alloys. Here, we quantify the hydrogen distribution in fully β and α+β Ti-Mo alloys by using atom probe tomography. Hydrogen does not segregate at grain boundaries in the fully β sample but segregates at some α/β phase boundaries with a composition exceeding 20 at.% in the α+β sample. No stable hydrides were observed in either sample. The hydrogen concentration in β phases linearly decreases from ~13 at. % to ~4 at. % with increasing Mo-content, which is ascribed to the suppression of hydrogen uptake by Mo addition.

Solute hydrogen and deuterium observed at the near atomic scale in high-strength steel

“…However, on closer inspection of our experimental data from W3, it appears that at least 80% of the H detected is from the specimen itself, whether from within the core of the specimen or adsorbed at the surface. This observation agrees with recent studies on other alloy systems which have also suggested that the H being detected at m/q = 1 Da most likely originates from the specimen [21,22]. It follows then that the H distribution in the datasets before heating is statistically significant enough to highlight real microstructural segregation and partitioning within the alloy itself, albeit with no control over the conditions of H intake, i.e.…”

“…If exposure to atmosphere could lead to H ingress, likely to a small extent, H uptake could well occur during the specimen preparation. However, recent evidence has pointed to the introduction of significant amounts of H in Ti and Ti-alloys during FIB-based specimen preparation [18,22]. These reports agreed well with the literature that pointed to the formation of hydrides from mechanical and electrochemical polishing and ion beam-based preparation of specimens for microscopic investigations [37][38][39].…”

“…Results on H/D analysis using APT for solutes and stable hydrides remain limited but reports can be found in the literature for multilayered materials [13,19], Ti-based [20][21][22][23] or Zr-based alloys [24] for instance. Deuteration is however not without challenges since H can be detected both as atomic ions, i.e.…”

The role of β pockets resulting from Fe impurities in hydride formation in titanium

“…An additional challenge arises from the undesired hydrogen introduction during the specimen preparation for microscopic observations, which cannot be easily avoided. However, previous work has shown that the combination of cryogenic sample preparation via focused ion beam (FIB) and atom probe tomography (APT) can reveal the distribution of H in titanium alloys with sub-nanometer resolution [17][18][19][20]. In addition, due to the low solubility of H in α, traditional characterization methods are insufficient to evaluate the H distribution and its effect, and many studies rely on artificially introduced H in the materials via H-charging [21][22][23].…”

Could face-centered cubic titanium in cold-rolled commercially-pure titanium only be a Ti-hydride?

“…Another technique to characterize hydrogen is atom probe tomography (APT). APT, as a mass spectroscopy technique with unparalleled spatial resolution, enables the characterization and visualization of the 3D distribution of hydrogen at the sub-nanometer scale within various metallic materials, e.g., steels [42,43], Zr alloys [44][45][46] and Ti alloys [33,47].…”