Neutron Imaging Analysis of Hydrogen Content in Pure Palladium and Aluminum Alloys

Abstract

The visualization of hydrogen distribution in materials is important to understand hydrogen embrittlement behavior. Neutron imaging experiment was carried out in order to visualize the distribution of solute hydrogen in an Al-10.1％Zn-1.2％Mg alloy and a pure palladium after hydrogen charging. Changes in the contrast of neutron transmission images caused by hydrogen were clearly observed in a palladium. In the wavelength range of 2-3 Å and 5-13.5 Å, the mean neutron transmission around the center of a hydrogen-charged palladium were 0.692 and 0.511, respectively. The hydrogen content in a palladium was estimated to be 10.8 mol％ from the measured neutron transmission. In this study, it has been demonstrated that hydrogen content can be analyzed even in non-monochromatic neutron imaging by considering the wavelength dependence of neutron intensity, and the effects of incoherent scattering and of Bragg-edge on transmission. On the other hand, hydrogen could not be observed from the neutron transmission image in Al-Zn-Mg alloys. This was due to the low hydrogen content, which was mass ppm level even after hydrogen charging, and statistical precision was not sufficient to discuss the amount of hydrogen of the mass ppm order.