Activation energy jump in the force dependence of the steady-state creep rate during tension of aluminum and lead

The activation parameters are estimated at the steady stage of creep during tension of aluminum and lead in the range of the exponential and power stress dependences of the steady-state creep rate. A jump of the effective activation energy is shown to occur in the stress dependence of the creep rate at $T\ge 0.5T_m$. This jump is approximately equal to the difference between the activation energies of self-diffusion and pipe diffusion.