Flow stress and creep rate of nanocrystalline Ni

Stress-strain curves of nanocrystalline Ni are compared to reported creep rate-strain curves at 298 and 373 K. Both show a limited range of strong work hardening followed by a steady-state. The stress dependence of the steady-state creep rate explains the continuous decrease in creep rate found in tests at constant load. The stress exponent of strain rate, n, decreases markedly with decreasing stress, but does not reach the low level commonly expected for Coble creep or grain boundary sliding. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.