Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Size-strength effects in sapphire and silicon nitride whiskers at 20° C

  • 59 Accesses

  • 23 Citations


Tensile tests at 20° C have been carried out on seventy-three sapphire whiskers and on seventeen silicon nitride whiskers. The sapphire whiskers were of 〈0001〉, 〈1¯120〉, 〈10¯10〉, and 〈10¯11〉 orientations, while the silicon nitride whiskers were 〈0001〉, 〈11¯20〉, and 〈10¯13〉. Tensile strengths were in the range 45 to 1500 kg/mm2, and deformation was found to be purely elastic. The tensile strength data have been analysed and fitted to empirical equations describing the effect of size on strength for different orientations. These empirical equations have been used to deduce possible fracture nucleation mechanisms. It is concluded that, in the case of 〈0001〉 sapphire whiskers, fracture nucleation may be due to dislocation pile-ups or interactions, while in the other cases a Griffith flaw mechanism is probably applicable.

This is a preview of subscription content, log in to check access.


  1. 1.

    S. S. Brenner, “Growth and Perfection of Crystals”, edited by R. H. Doremus, B. W. Roberts, and D. Turnbull (Wiley, New York, 1958), p. 162.

  2. 2.

    Z. Gyulai,Z. Physik 138 (1954) 317.

  3. 3.

    R. Regester et al, General Electric Co, MSD Eighth Quarterly Report, Contract NoW 60-0465d (May 1962).

  4. 4.

    S. S. Brenner,J. Appl. Phys. 33 (1962) 33.

  5. 5.

    P. J. Soltis, Report No. NAEC-AML-1831 (March 1964). See alsoSymp. Amer. Ceram. Soc. (May 1965).

  6. 6.

    R. H. Kelsey andR. H. Krock, “Some Observations and Results on Tensile Testing Alumina Whiskers” (P. R. Mallory & Co Inc, Burlington, Mass, USA).

  7. 7.

    R. L. Mehan, E. Feingold, andA. Gatti, General Electric Space Sciences Laboratory Report R 65SD36 (August 1965).

  8. 8.

    W. W. Webb andW. D. Forgeng,J. Appl. Phys. 28 (1957) 1449.

  9. 9.

    P. D. Bayer, C. A. Calow, andG. P. R. Mccarthy, to be published.

  10. 10.

    J. M. Gordon, private communication.

  11. 11.

    R. W. Guard andP. C. Romo,J. Amer. Ceram. Soc. 48 (1965) 7.

  12. 12.

    F. J. P. Clarke, H. G. Tattersall, andG. Tappin,Proc. Brit. Ceram. Soc. 6 (1966) 163.

  13. 13.

    J. Congleton andN. J. Petch,Acta Met. 14 (1966) 1179.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Bayer, P.D., Cooper, R.E. Size-strength effects in sapphire and silicon nitride whiskers at 20° C. J Mater Sci 2, 233–237 (1967). https://doi.org/10.1007/BF00555379

Download citation


  • Polymer
  • Silicon
  • Tensile Strength
  • Nitride
  • Tensile Test