On measured activation volumes as relevant to ratcheting or cyclic creep

We consider a material having a constant true activation volume and estimate the apparent activation volume that it displays in cyclic creep or ratcheting. We show that cyclic stresses have an effect on the measured value, and that this can be accounted for in data interpretation. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.