Microstructures and mechanical properties of a Cu-Zn alloy subjected to cryogenic dynamic plastic deformation

The microstructures and mechanical properties of a Cu-Zn alloy subjected to dynamic plastic deformation (DPD) at liquid nitrogen temperature (77 K) were investigated. The planar dislocation activities, deformation twinning and shear banding dominate the plastic deformation of samples with different strains, respectively. Twin boundary spacing decreases with strain and nearly saturates when the strain exceeds 1.2. Shear bands occur within high-density twin region at higher strains, inside which nano-sized grains are formed. Tensile tests show that the DPD brass exhibits a high strength and a limited tensile ductility. Deformation twins play an important role in the strengthening while the appearance of shear bands obviously reduces the ductility of materials.