The Contribution of the Dislocation Forest to the Flow Stress

The formation of junctions between a moving dislocation and the trees of a dislocation forest has been calculated for f.c.c. crystals. In contrast to previous estimates the concept of the orientation‐dependent line energy and a more realistic averaging procedure was used. In a random forest in which the tree length is equal to the tree separation only about 20% of the trees form junctions. The stress to overcome the junctions is higher for screw dislocations than for edges but the exact values depend on the nature of the forest.