Internal friction of very high purity lead (99.9999%) at medium temperatures

Internal friction spectra Of high purity lead (99-9999%) at medium temperat ures exhibit a main relaxation peak at 230 K (P-1) which depends strongly o n the dislocation arrangement. The mechanism associated to P-1 relaxation b as an activation area between 500b(2) and 2000b(2) and its activation energ y is 0.65 +/-0.05 eV (63 +/-5 KJ/mol), which is only 0.6 times the autodiff usion energy of lead. The behaviour of P-1 peak and its dependence on therm omechanical treatments has allowed us to Conclude that it is associated to the Sliding of dislocations controlled by thc climbing of jogs by diffusion of vacancies along the dislocation Lines. At a slightly higher temperature , another relaxation (P-1) turns up in the spectral which can be associated to different mechanisms.