High Purity Ultrafine‐Grained Nickel Processed by Dynamic Plastic Deformation: Microstructure and Mechanical Properties

Abstract Bulk ultrafine‐grained samples are processed by dynamic plastic deformation at an average strain rate of 3.3 × 10² s⁻¹ from bulk coarse‐grained nickel with purity higher than 98.4 wt.%. The obtained microstructure is investigated by electron backscattering diffraction, transmission electron microscopy and X‐ray line profile analysis. After dynamic deformation the microstructure evolves into submicron‐size lamellar and subgrain structures. Evaluation of average grain size shows a heterogeneous microstructure along both the diameter and the thickness of the sample. X‐ray line profile analysis reveals high dislocation density of about 13 ± 2 × 10¹⁴ m⁻² in the impacted material. The mechanical properties are investigated by means of uniaxial quasi‐static compression tests conducted at room temperature. The stress–strain behavior of the impacted Ni depends on the location in the impacted disk and on the orientation of the compression axis relative to the impact direction.