2022 Volume 72 Issue 8 Pages 482-484
In this study, hydrogen incorporated into 7075 aluminum alloy substrates by electroless Ni-P plating was investigated. In the cross-sectional transmission electron microscope images, a low phosphorus content (5.7mass%) film consisted of fine grains and a high phosphorus content (12.1mass%) film consisted of an amorphous phase were observed on the 7075 alloy substrates. Depth profile analysis by glow discharge optical emission spectrometry revealed that the intensity of hydrogen increased in the 7075 alloy substrate after electroless Ni-P plating, and was higher at the interface between the Ni-P film and the 7075 alloy substrate. In the thermal desorption spectra of hydrogen from the 7075 alloy substrates with low and high phosphorous content Ni-P films, a pronounced desorption peak and a series of desorption peaks were observed. Such desorption peaks were not observed in the 7075 alloy substrate before electroless Ni-P plating and in the Ni-P films on the copper substrates. These results indicate that the hydrogen incorporated into the 7075 alloy substrate by electroless Ni-P plating exists in various trap sites such as interstitial sites, vacancies, grain boundaries, and the incoherent interface between the precipitates and the aluminum basal phase.
