Oxygen‐induced surface segregation of hydrogen in polycrystalline titanium

Abstract

Oxygen-induced surface segregation of hydrogen has been investigated in polycrystalline titanium. It was found that sulphur impurities in titanium preferentially segregate to the surface on heating the sample. Consequently, the properties and reactivity of the sulphur-containing surfaces were modified relative to sulphur-free samples in a way which enabled the performance of quantitative kinetic segregation measurements utilizing direct recoil spectrometry (DRS). The time behaviour of hydrogen accumulation on the surface pointed to a segregation mechanism involving subsurface-to-surface hopping as the rate-determining step.

Materials science and engineering

“…Subsequently, the desorption atmosphere was changed to air, resulting in a strain decrement of 1.2% (E). This behavior is attributed to the need of oxygen, and possibly some humidity, to catalyze the hydrogen atoms recombination on the metal surface [30]. Further cycling experiments were conducted at various stresses (F and G) between 95 and 190 MPa, with strain increments of up to 3.7% after a complete hydriding-dehydriding cycle.…”