Creep of nanocrystalline nickel: A direct comparison between uniaxial and nanoindentation creep

Uniaxial and nanoindentation creeps were conducted on nanocrystalline nickel with an as-deposited grain size of 14 nm at 398 K and the results were directly compared. The stress exponent under the two test conditions was found to be almost the same, indicating a similar creep mechanism. However, the strain rate measured by nanoindentation creep was about 100 times faster than that by uniaxial creep. The rate difference was discussed in terms of stress states and the appropriate selection of the Tabor factor.