Influence of Plastic Deformation on the Accumulation of the Average Scalar Dislocation Density and Its Components pS and pG in Cu-Mn Alloys

Abstract

The development and progress of the physical science of strength makes it possible to formulate the main aspects based on dislocation physics. This article describes the current state of this issue in the framework of a multilevel approach. It considers the patterns of accumulation of dislocations in a material after various degrees of deformation. The main mechanism of hardening of a metal polycrystal is the accumulation of dislocations in its grains, and the main hardening parameter is the average scalar dislocation density. The scalar dislocation density is divided into components: the density of statistically stored (pS) and the density of geometrically necessary (pG) dislocations. Transmission diffraction electron microscopy (TEM) is used to study the stages of the development of types of dislocation substructure (DSS) in Cu-Mn alloys depending on the concentration of the alloying element during active plastic deformation. Polycrystalline alloys were investigated over a wide concentration range from 0.4 to 25 atomic percent Mn. A number of parameters of the dislocation substructure are measured from micrographs obtained in an electron microscope: the average scalar density of dislocations <p>, the density of statistically stored (pS) and geometrically necessary (pG) dislocations, the curvature-torsion of the crystal lattice (х), the density of microbands (b), density of dangling subboundaries (Msub). A sequence of transformations of DSS types with an increase in the degree of deformation and the value of the second element to form the type of substructure and its parameters is established. The influence of the concentration of the second element and the grain size on the average scalar density of dislocations and its components is experimentally determined. The presence of misorientations in the substructure during deformation is based on the measurement of these parameters using the TEM method.