A study of cross-slip activation parameters in pure copper

Abstract

A new experimental technique was recently developed in order to investigate the intrinsic features of cross-slip in f.c.c. crystals [J. Bonneville and B. Escaig, Acta metall.27, 1477 (1979)]. The technique consisted of predeforming a large single crystal in such a way that, by straining new samples cut from it, a situation was created where a burst of cross-slip events was produced at yield. This paper reports the application of the above technique to the measurements of the activation volume and energy associated with the cross-slip mechanism in copper at temperatures between 150 and 473 K. Between 250 and 410 K, a cross-slip activation volume of 350ν(ν = b332) has been measured and the energy barrier of this mechanism has been estimated to be of the order of 1.15 ± 0.37 eV. Transmission electron microscopy observations were also performed, including conventional and in-situ experiments, to characterize the dislocation forests and to directly observe the cross-slip process. All of these results are in good agreement with the prediction of Escaig's model for cross-slip of the f.c.c. structure. At lower and higher temperatures the predeformation substructure is not stable and the cross-slip burst is screened by other processes.