Internal friction and oxygen pair diffusion in α-zirconium

Internal friction of high-purity zirconium-oxygen alloys has been measured with an inverted torsion pendulum apparatus having a very low background damping. A damping peak originating from low-strength anelastic relaxation has been detected at 410°C: 0.44 Hz. Increasing the oxygen content has produced a significant increase in the relaxation strength and a consequent increase in the magnitude of the damping peak. A mechanism involving stress-induced diffusion of oxygen atoms in the basal plane of the hcp lattice has been proposed as the only relaxation process capable of producing the observed damping behaviour. The diffusion coefficient based on the proposed diffusion mechanism and derived from the experimental data is D = 1.5 × 10⁻⁴ exp (−48 OOO/RT) m²s⁻¹.