Influence of Beryllides on the Corrosion of Commercial Grades of Beryllium

The bulk form of the Be intermetallics FeAlBe4, FeBe5, and TiBe12 were examined in solutions ranging in pH from 2 to 12.5 at ambient temperature. The intermetallics were manufactured by arc-melting stoichiometric amounts of Be and the alloying elements Al, Ti, and Fe as indicated. Composition and structure were verified with x-ray diffraction. Polarization data along with open-circuit potential measurements were used to make mixed potential predictions of the electrochemical activity of the beryllides in commercial grades of Be. These predictions were verified for FeBe5 by arc-melting a button consisting of Be-10 at% FeBe5. For near-neutral and slightly alkaline pH, the beryllides were passive at all potentials examined. In pH 2 solution, the beryllides were active. To characterize the oxide film on as-prepared and post-immersion samples, angle-resolved x-ray photoelectron spectroscopy (XPS) was used. In general, the near-surface oxide was stoichiometric to hyper-stoichiometric oxidized Be. In some cases, selective dissolution was observed in the XPS data. In all cases, the oxide formed on samples exposed to pH 2 solution was thinner as compared to as-polished samples