Mechanisms of slip mode modification in F.C.C. solid solutions

While it is widely recognized that alloy factors other than stacking fault energy play a role in promoting planarity of slip, no detailed model has been advanced to explain the mechanism of planar vs wavy slip mode. Therefore, friction stress effects of alloying on disolcation behavior are reviewed, as well as the role of stacking fault structure in inhibiting the clustering of dislocations in planar slip metal. A model of cross-slip inhibition (and thus planar slip behavior) is developed from the idea that the joining of partials is resisted by frictional effects. Planarity of slip is promoted not only by low stacking fault energy but by increase in shear modulus, atomic size misfit and solute content. A critical solute concentration is predicted by the model for the transition from wavy slip to planar slip and this is shown to be in good agreement with observations for copper base solid solutions and other alloy systems.