Microstrain in nanocrystalline solids under load by virtual diffraction

¹  Universität des Saarlandes, FR7.3 Technische Physik - Saarbrücken, Germany, EU
²  Karlsruher Institut für Technologie, Institut für Nanotechnologie - Karlsruhe, Germany, EU
³  Karlsruher Institut für Technologie, Institut für Zuverlässigkeit von Bauteilen und Systemen Karlsruhe, Germany, EU
⁴  Russian Academy of Science, Institute for Metals Superplasticity Problems - Ufa, Russia
⁵  Fraunhofer-Institut für Werkstoffmechanik - Freiburg, Germany, EU

Corresponding author: j.markmann@nano.uni-saarland.de

Received: 23 November 2009
Accepted: 22 February 2010

Abstract

We propose a method for computing virtual X-ray diffractograms for nanocystalline materials under uniaxial load based on molecular-dynamics simulation data. While the increase in diffraction microstrain during deformation is generally taken as evidence for the generation of lattice dislocations, our virtual diffraction data show extra microstrain even at small load, before the onset of lattice dislocation activity. We show that the microstrain data have a natural explanation in the elastic response of a heterogeneous medium. The results imply that the conclusions of previous experimental in situ diffraction data for nanocystalline metals may deserve a critical examination.