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Journal of Materials Science

, Volume 9, Issue 5, pp 794–800 | Cite as

Work hardening and recovery during compressive creep of polycrystalline MgO

  • J. M. Birch
  • B. Wilshire
Papers

Abstract

High precision equipment has been used to study the effects of small stress changes during steady state creep of magnesia at 1596 K. When the stress,σ1, is reduced by a small amount,Δσ, the creep rate decreased to zero for a period,Δt, before accelerating to a new steady value. Calculating the rate of recovery,r(=−δσ/δt) asΔσ/Δt and the coefficient of strain hardeningh(=δσ/δε) asΔσ/Δε (whereΔε is the instantaneous strain recorded on increasing the stress byΔσ) gave the ratio,r/h, which predicts accurately the observed steady creep rate,\(\dot \in _s \). It is proposed that when\(\dot \in _s \)∝ σ3, creep is recovery controlled. The results are explained in terms of a model for creep in which the rate controlling process is the growth of the 3-D dislocation network within subgrains, to form dislocation sources allowing slip to occur.

Keywords

Polymer Magnesia Steady State Work Hardening High Precision 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    T. Vasilos, J. B. Mitchell andR. M. Spriggs,J. Amer. Ceram. Soc. 47 (1964) 203.Google Scholar
  2. 2.
    E. M. Passmore, R. H. Duff andT. Vasilos,ibid 49 (1966) 594.Google Scholar
  3. 3.
    T. Zisner andH. Tagai,ibid 51 (1968) 310.Google Scholar
  4. 4.
    R. S. Gordon andG. R. Terwilliger,ibid 55 (1972) 310.Google Scholar
  5. 5.
    F. R. N. Nabarro, “Report on Conference on The Strength of Solids”, University of Bristol, July 1947 (The Physical Society, London, 1948) p. 75.Google Scholar
  6. 6.
    C. Herring,J. Appl. Phys. 21 (1950) 437.Google Scholar
  7. 7.
    R. L. Coble,ibid 34 (1963) 1679.Google Scholar
  8. 8.
    T. G. Langdon andJ. A. Pask,Acta Metallurgica 18 (1970) 505.Google Scholar
  9. 9.
    J. H. Hensler andG. V. Cullen,J. Amer. Ceram. Soc. 51 (1968) 557.Google Scholar
  10. 10.
    J. B. Bilde-Sorenson,ibid 55 (1972) 606.Google Scholar
  11. 11.
    N. F. Mott, “Creep and Fracture of Metals at High Temperatures” (HMSO, London, 1956) p. 21.Google Scholar
  12. 12.
    J. Weertman.J. Appl. Phys. 28 (1957) 1185.Google Scholar
  13. 13.
    W. R. Cannon andO. D. Sherby,J. Amer. Ceram. Soc. 56 (1973) 157.Google Scholar
  14. 14.
    J. Weertman,J. Appl. Phys. 26 (1955) 1213.Google Scholar
  15. 15.
    Idem, ibid 28 (1957) 362.Google Scholar
  16. 16.
    S. K. Mitra andD. Mclean,Proc. Roy. Soc. A 295 (1966) 288.Google Scholar
  17. 17.
    P. W. Davies andB. Wilshire,Scripta Met. 5 (1971) 475.Google Scholar
  18. 18.
    R. F. Canon, J. T. A. Roberts andR. J. Beals,J. Amer. Ceram. Soc. 54 (1971) 105.Google Scholar
  19. 19.
    E. Orowan,J. West Scot. Iron and Steel Inst. 54 (1946) 45.Google Scholar
  20. 20.
    C. K. L. Davies, P. W. Davies andB. Wilshire,Phil. Mag. 12 (1965) 827.Google Scholar
  21. 21.
    D. Sidey andB. Wilshire,Metal Sci. J. 3 (1969) 56.Google Scholar
  22. 22.
    R. G. St-Jacques andR. Angers,J. Amer. Ceram. Soc. 55 (1972) 571.Google Scholar
  23. 23.
    R. L. Bertolotti andW. D. Scott,ibid 54 (1971) 286.Google Scholar
  24. 24.
    G. M. Fryer andP. Thompson,Trans. Brit. Ceram. Soc. 71 (1972) 61.Google Scholar
  25. 25.
    R. D. Cropper andJ. A. Pask,Ceram. Bull. 48 (1969) 355.Google Scholar
  26. 26.
    D. R. F. Spencer,Trans. Brit. Ceram. Soc. 11 (1972) 123.Google Scholar
  27. 27.
    P. W. Davies andR. Dutton,J. Sci. Instrum. 43 (1966) 39.Google Scholar
  28. 28.
    E. M. da C. Andrade andB. Chalmers,Proc. Roy. Soc. A 138 (1932) 348.Google Scholar
  29. 29.
    L. E. Poteat, Ph.D. Thesis, North Carolinia State University, Raleigh, NC (1966).Google Scholar
  30. 30.
    D. Mclean,Rep. Prog. Phys. 29 (1966) 1.Google Scholar
  31. 31.
    F. R. N. Nabarro,Phil. Mag. 16 (1967) 231.Google Scholar
  32. 32.
    J. Friedel, “Dislocations” (Pergamon Press, London, 1964).Google Scholar

Copyright information

© Chapman and Hall Ltd. 1974

Authors and Affiliations

  • J. M. Birch
    • 1
  • B. Wilshire
    • 1
  1. 1.Department of Metallurgy and Materials TechnologyUniversity College of SwanseaSingleton ParkUK

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