EFFECT OF STACKING-FAULT ENERGY ON STRUCTURAL-CHANGES UPON MECHANICALACTIVATION

The effect of bail milling on dhe kinetics of changes in dislocation d ensity rho and concentration of stacking fault in annealed powders of nickel and Co-Ni alloys (with 20. 40. and 60% Co) substantially differ ent in stacking-fault energy were studied by analysis of shapes and an gle positions of ill, 200. 311. and 222 reflections in X-ray diffracti on patterns. It was established that the lower is stacking-fault energ y, the more rapidly rho increases and reaches maximum. The maximum rho value increases with stacking-fault energy. This is explained by the suppression of dynamic recovery due to high deformation race upon mech anical activation.