Preparation and mechanical properties of bulk nanocrystalline nickel

The bulk nanocrystalline nickel was prepared by DC arc plasma evaporation method and pre-press sintering. The grain size and porosity was characterized; the compression strength, the strain-rate sensitivity and the influence of the compression process on the grain size and lattice distortion of the specimens were investigated. The results show that the grain size increases with higher sintering temperature. At 725°C, the relative density of the bulk nanocrystalline nickel is 97%. The compression strength increases with smaller grain size and it is proportional to the strain rate, and the highest compression fracture strength is 600 MPa. The specimen exhibits lower sensitivity to strain rate and lower working hardening exponent. The damage mechanism of the bulk nanocrystalline nickel is intergranular fracture, and the compression leads to the decrease of the grain size and lattice distortion.