The results of a study of the dislocation structure evolution in polycrystals of homogeneous solid solutions in low-stability states in Cu-Mn-based alloys with FCC crystal lattice are presented. It is found out that each stage is characterized by its own deformation carrier in the form of a certain dislocation substructure (DSS), whose volume fraction has a maximum in this stage. At the same time, the deformation carrier of the previous stage gradually disappears as the strain degree (epsilon) increases in the current stage, and there appears a deformation carrier of the subsequent stage. In a certain range of epsilon values, the deformation carriers characteristic of the previous, current and subsequent stages coexist. It is shown that there are transitions from some types of DSS to other types in certain strain degree epsilon intervals. It is revealed that each deformation stage has its own DSS - deformation carriers. The stage-to-stage transition is accompanied by the formation of new deformation carriers, which is a characteristic feature of low-stability states of the system. Logically, this situation is observed because the study is carried out at a grain size involving a possibility of implementing a low-stability structural-phase state of the alloy, since in this case the grain size acts as a kind of a governing parameter.