Compressive-tensile deformation of nanocrystalline nickel at high pressure and temperature conditions

We conducted uniaxial compressive and tensile deformation on nanocrystalline Ni at a confining pressure of 6 GPa and temperatures up to 900 degrees C. The determined compressive yield strength is 0.8 GPa, identical to the tensile yield strength obtained in the same deformation experiment, indicating that the Bauschinger effect is absent in nanocrystalline Ni. The yield strength obtained at 6 GPa is also comparable to that at ambient pressure, suggesting that the dislocation-mediated mechanisms are no longer activated during plastic deformation. Based on peak intensity and peak width analyses, grain rotation and grain growth are main factors underlying the plastic deformation. (C) 2013 AIP Publishing LLC.