No 1, Vol. 5, 2002 


C.S. Pande1, R.A. Masumura1 and P.M. Hazzledine2

1 Materials Science and Technology Division,
Naval Research Laboratory, Washington, DC 20375-5343 USA
2 U. E. S. Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432, USA


Modeling of strengthening by nanocrystalline materials need consideration of both dislocation interactions and sliding due to Coble creep acting simultaneously. Such a mechanism is considered in this paper. It is shown that a model based on using Coble creep (with a threshold stress) for finer grains and conventional Hall-Petch strengthening for larger grains, appears to be most successful in explaining experimental results provided a grain size distribution is incorporated into the analysis to account for a distribution of grain sizes occurring in most specimens. Use of an alternate formalism of Coble creep proposed recently gives a somewhat less satisfactory agreement with experiments

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