FLOW-STRESS AND ACTIVATION VOLUME OF SOME COLD-WORKED COPPER-BASED SOLID-SOLUTIONS

In cold‐worked solid solutions the moving dislocations meet two sets of obstacles in their glide plane: solute atoms and forest dislocations. For this case a theory by Kocks predicts that the flow stresses due to both types of obstacles are additive, and so are the inverse activation volumes. The theory is tested on Cu based solid solutions, containing 0.5 to 10% Ni,Zn, or Au. It is found that the additivity of flow stresses holds in all cases, whereas the additivity of inverse activation volumes only holds for CuNi. For CuZn and CuAu the relation between the activation volumes is found to be V−1 = (V1)−1 + h(V 2−1) where h is a constant ± 1. The obstacle strengths of the solute atoms and dislocation intersections are determined from the experimental results. It is concluded that in an activated jump of a dislocation segment many solute atoms (of the order 10 to 50) are surpassed. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA