Investigations on the transition from jerky to viscous glide in CuAl at elevated temperatures

A study on the transition from discontinuous (jerky) to continuous (viscous) dislocation motion in polycrystals of f.c.c. Cu 10 at.% Al is presented. This transition has been investigated by measurements of the critical flow stress. It is found to depend not only on temperature but also on strain rate. Additionally, measurements have been performed under conditions of constant stress, i.e. creep tests. Changes from constant strain rate testing to creep conditions are used to check whether dislocations glide discontinuously or continuously at higher stresses. At a certain stress level, depending on temperature and strain rate, the deformation conditions are found to change from discontinuous to viscous glide.