Vacancy-Hydrogen Defects in Aluminum Formed During Aqueous Dissolution
K. R. Hebert, J. Ai, Gery R. Stafford, K. M. Ho, C. Z. Wang
Aqueous dissolution of aluminum is accompanied by extensive absorption of hydrogen, along with formation of hydride and voids. We used in situ stress measurements to discriminate between absorption mechanisms leading to either interstitial or vacancy-hydrogen (Vac-H) defects, and to relate defect formation to surface chemistry. Large tensile shifts of the stress-thickness product, approaching 35 N/m, were found during the initial exposure of Al thin films to aqueous NaOH solutions at pH 12 to 13. The time dependence of the stress-thickness product correlated with mass of metal dissolved, as determined with the quartz crystal microbalance. The observed relationship between stress and mass change was consistent with a high fraction of dissolved Al atoms forming vacancy-hydrogen (Vac-H) defects. Electrochemical potential transients indicated that the onset of the tensile stress change corresponds to the presence of aluminum hydride at the metal surface. We propose a dissolution mechanism in which interfacial hydride produces an elevated hydrogen chemical potential, stabilizing Vac-H defects.
, Ai, J.
, Stafford, G.
, Ho, K.
and Wang, C.
Vacancy-Hydrogen Defects in Aluminum Formed During Aqueous Dissolution, Electrochimica ACTA, [online], https://doi.org/10.1016/j.electacta.2010.08.052
(Accessed December 11, 2023)