異なる環境に暴露したアルミニウムにおける水素の挙動

抄録

Hydrogen in aluminum alloys frequently causes degradation of mechanical properties and surface quality of the products. Thus, the behavior of hydrogen in aluminum has been extensively studied. However, there has been an appreciable controversy in whether hydrogen intrudes the aluminum when exposed to air with moisture. In this study, hydrogen behavior in a pure aluminum foil that had been dehydrogenated and subsequently exposed to mainly air at temperatures ranging from room temperature to 550°C was analyzed by means of TDS, thermal desorption spectroscopy. In the specimens exposed to air and water at room temperature, hydrogen evolution was clearly observed at temperatures above about 450°C in the TDS spectra. This means that moisture at the specimen surface was converted to atomic hydrogen through the reaction with aluminum which subsequently diffuses into the specimen and is trapped by certain sites. Additionally, the specimens were annealed at several temperatures and humidities for 1 h. In the specimens exposed to air at different temperatures and humidity, the amount of hydrogen contained in the specimens was increased as the humidity and the temperature. Two peaks were seen at about 450 and 550°C in the spectra of the specimens containing large amount of hydrogen, and were found to correspond to the hydrogen trapped by dislocations and micro pores, respectively.