Types of mechanical relaxation by hydrogen in intermetallic compounds

Hydrogen in polycrystalline intermetallic compounds generally produces extremely broad damping spectra, indicating the presence of short-range as well as long-range relaxation mechanisms. These are discussed on the basis of vibrating-reed results on Zr65Cu27.5Al7.5, Zr65Cu17.5Ni10Al7.5, and CuZr2 alloys. A relaxation peak at 270 K observed in all three cases is interpreted as a Zener-type relaxation of hydrogen in the CuZr2 lattice. The differences found at higher temperatures –– a second relaxation peak in the ternary and quaternary alloys but an exponential increase of damping in CuZr2 –– are related to different grain sizes and can be attributed to an `intercrystalline Gorsky effectʹ due to elastic anisotropy mismatch strains.