Mechanical Properties of Nanocrystalline and Ultrafine-Grained Nickel with Bimodal Microstructure


  • Tao Qian and Michael Marx acknowledge the support of this work by the Deutsche Forschungsgemeinschaft (DFG), Grant No. MA 3322/3-1. I. Karaman acknowledges the support from the National Science Foundation, Grant No. DMR-08-44082, which supports the International Materials Institute for Multifunctional Materials for Energy Conversion (IIMEC) at Texas University. Finally, the authors thank Kerstin Schueler for producing the PED nickel plates.


The aim of this work was to use bimodal microstructures to improve ductility and fatigue resistance of nanocrystalline (NC) and ultrafine-grained (UFG) materials while keeping the materials’ high strength. Nickel plates produced by pulsed electrodeposition were used as NC base material while as UFG base material high-purity nickel was processed by equal channel angular pressing. After different heat treatments, bimodal microstructures could be realized in the size ranges of NC/UFG and UFG/coarse grained (CG). While the UFG/CG nickel revealed an improved ductility but little influence on the fatigue resistance, the NC/UFG nickel shows an extraordinary fatigue resistance.