Damping spectrum of H-free and H-doped shape memory alloys NiTiHfCu at kHz frequencies

The internal friction, the Young's modulus and the heat flow have been measured as a function of temperature in the Ni 47Ti 40Hf 10Cu 3 alloy. H-doping introduces two anelastic relaxations P H and P H ′ . P H is a Snoek-type effect ( W H=0.60±0.1 eV, τ 0H=2×10 −(16±1) s) also occurring in NiTi(Cu) alloys. P H ′ is a new phenomenon due to quantum-mechanical transitions of H bound to Hf atoms and located at tetrahedral interstitial sites.