Evolution of Dislocation Substructure in Deformed Ordered and Disordered Pd3Fe Alloys in Low-Stability State

The paper presents the results of the transmission electron microscopy of the evolution of the dislocation substructure (DSS) of the polycrystalline ordered and disordered Pd3Fe alloys with low-stable structure and phase compositions. A flow chart is suggested for the transformation of the dislocation substructures during a transition from one stage to another. These stages are indicated on the stress-strain curves of the Pd3Fe alloy. It is found that in the case of both disordered and ordered alloys, each deformation stage is characterized by a specific dislocation substructure, which is the main deformation medium for each stage. A transition from one DSS type to another occurs at a certain range of the deformation degree. The DSS type characteristic to a given stage of deformation appears at a preceded stage and its amount increases with the deformation growth. At a given deformation stage, this amount is the highest, while during the transition to another stage, it gradually lowers and disappears. In the ordered alloys, the DSS types differ from those in the disordered alloys at the same deformation stage. It is shown that at each deformation stage, there are specific dislocation substructures or deformation media. During the transition to a new stage, the transition to a new structural deformation media occurs, and these media exist together. This is characteristic to the low-stability state of the whole system.