The present experimental knowledge of dynamic strain ageing in binary f.c.c. solid solutions

A comparative study of dynamic strain ageing (DSA) in face centred cubic solid solutions is presented. In particular, investigations on CuMn and CuAl for various concentrations are reported extending over full stress strain curves in a wide range of temperatures, T. We obtain complete maps of boundaries of stable deformation for increasing T revealing the subsequent onset of three thermally activated processes, each one inducing DSA. The activation energies EI, EII, EIII which can be determined on two different ways are well below the volume diffusion energy. Additionally, for the strain rate exponent never the volume diffusion value n = 2/3, but n = 0.33 ± 0.07 is found in any case. The results on the Eʹs and n strongly suggest linear (pipe, core) diffusion modes to be relevant for the DSA processes observed. Owing to gaps in present theory only possibilities for the existence of several such modes can be outlined.