Formation of Fragments and Microbands During Deformation in Cu-Al and Cu-Mn Alloys with Different Concentrations of the Second Element

The dislocation structure during deformation of polycrystalline FCC solid solutions of the Cu-Al and Cu-Mn systems was studied using transmission electron diffraction microscopy. The Al content in the Cu-Al alloys varied from 0.5 to 14 at.%, while the Mn content in the Cu-Mn alloys varied within 0.4 ... 25 at.%. Types of forming dislocation substructures were determined by analyzing the electron microscopic patterns obtained for thin foils of the studied alloys deformed to different degrees. Microbands densities, widths, and distances between microbands in the defect structures were measured for each sample. There were several stages during formation of fragmented and microband substructures found and proved experimentally to be dependent on the type and concentration of the alloying element. Only a fragmented substructure is formed in low-alloyed copper-aluminum alloys, and only a microband substructure is formed when the concentration of the second element, aluminum, increased. However, only a microband substructure is formed in Cu-Mn alloys during deformation regardless of the concentration of Mn atoms in such alloys.