Application of Hydrogen Micro-Imaging System for Quantitative Analysis of Hydrogen Behavior in Materials

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The purpose of the research is to develop hydrogen micro-imaging system for quantitative analysis of hydrogen behavior in materials. For this purpose, radioluminography and autoradiography was performed. In pure vanadium, local hydrogen concentration on the specimen surface depended on the surface orientation, that is, hydrogen concentration is higher at the grains with (001) crystal orientation compared with that with (111) orientation. This experiment enable us to examine a relation between the local hydrogen concentration and the position on the specimen. In the V-Zr-Ni-Ti alloy with BCC/Laves two phase structure, it was found that hydrogen preferentially penetrate into the specimen through the Laves phase. In this alloy, the local hydrogen concentration gradually decreased as the elapsed time after hydrogen charging at the region where higher ratio of the Laves phase, while the local hydrogen concentration decreased and then increased where higher ratio of the BCC phase. Hydrogen was thought to be moved to the Laves phase to the BCC phase. In the V_<95>Fe_5 alloy with BCC structure, it was found that the iron addition increases the hydrogen absorption rate, and that hydrogen distribution correlates with the iron segregation in the dendritic structure which formed during the solidification. In this experiment, the relation between the hydrogen concentration and iron concentration at the local area was obtained quantitatively. In the V_<35>Cr_<40>Ti_<25> alloy with BCC structure, it was found that hydrogen distribution correlates with titanium at the heat affected region during solidification, while hydrogen distribution has not clear correlation with the constituent element at the rapidly and slowly cooled region. In these regions, hydrogen distribution depended on the morphology of the dendritic structure.