Analysis of Hydrogen Content in Pure Palladium via Neutron Radiography and Tomography

Abstract

Hydrogen in materials degrades mechanical properties, which is widely recognized as hydrogen embrittlement. To understand hydrogen embrittlement, it is necessary to clarify the accumulation behavior of hydrogen under stress. The neutron radiography and neutron tomography techniques are applied to examine whether hydrogen accumulation behavior can be visualized directly. Palladium specimens with and without hydrogen were prepared for the neutron imaging experiment under stress. Solute hydrogen has caused distinct contrast change in both the neutron radiography and neutron tomography. Hydrogen distribution at a notch-tip in a loaded specimen has not been visualized in the tomographic cross-sectional images. It can be inferred that this is fundamentally attributable to low spatial resolution of the present imaging set-up, and possibility to visualize hydrogen distribution due to loading is discussed.

Fig. 7 Virtual cross-sections of the 3D neutron tomographic images; (a) palladium without hydrogen, (b) that with 10％ hydrogen, and (c) that with 10％ hydrogen after loading. (a) and (b) were observed without loading. (d) Line profiles were obtained from the white solid lines in (a)-(c).