Journal of Superhard Materials

, Volume 32, Issue 6, pp 406–414

Comparative studies of mechanical properties of stishovite and sapphire single crystals by nanoindentation

Authors

  • S. N. Dub
    • Bakul Institute for Superhard MaterialsNational Academy of Sciences of Ukraine
  • V. V. Brazhkin
    • Vereshchagin Institute of High Pressure PhysicsRussian Academy of Sciences
  • N. V. Novikov
    • Bakul Institute for Superhard MaterialsNational Academy of Sciences of Ukraine
  • G. N. Tolmachova
    • Kharkiv Institute of Physics and TechnologyNational Scientific Center
  • P. M. Litvin
    • Lashkarev Institute of Physics of SemiconductorsNational Academy of Sciences
  • L. M. Lityagina
    • Vereshchagin Institute of High Pressure PhysicsRussian Academy of Sciences
  • T. I. Dyuzheva
    • Vereshchagin Institute of High Pressure PhysicsRussian Academy of Sciences
Production, Structure, Properties

DOI: 10.3103/S1063457610060067

Cite this article as:
Dub, S.N., Brazhkin, V.V., Novikov, N.V. et al. J. Superhard Mater. (2010) 32: 406. doi:10.3103/S1063457610060067

Abstract

Comparative nanoindentation tests of stishovite and sapphire single crystals have been performed. It has been found that nanohardness of the (0001) plane of sapphire at a depth of 200 nm is 29.1 ± 0.1 GPa, while the nanohardness of the (110) plane of stishovite is 38.1 ± 0.6 GPa, the tests conditions being the same. The specifics of elastoplastic transition in sapphire and stishovite single crystals and alumina-based polycrystalline ceramic when plastic deformation is localized in a submicron region have been studied. Anomalous elastoplastic transition in stishovite has been revealed. A possibility that anomalous mechanical behavior of stishovite at the nanoscale may be due to a strong softening of the lattice as a precursor of the formation of a post-stishovite phase of silica with the CaCl2 structure in an indent has been discussed.

Key words

nanoindentationnanohardnesselasto-plastic transitionsapphirestishovite

Copyright information

© Allerton Press, Inc. 2010