Abstract
Strength and strain rate sensitivity measurements for nanopolycrystalline copper, nickel and aluminium materials are assessed on the basis of a Hall–Petch method of analysis. The H–P kε values are attributed to the need for cross-slip in the grain boundary regions. Transition of the H–P dependence to the stress for a single dislocation loop expanding against the grain boundary resistance provides an explanation of higher measurements for nanoscale aluminium material.
Acknowledgement
It is a great pleasure to acknowledge extended correspondence concerning the Jiang and Zhang analysis with Professor Wolfgang Blum, University of Erlangen-Nürnburg, but without committing him to agreement with the present description.