Impression Plasticity and Creep in Hard Crystals

  • E. Jill Brookes
  • Chris A. Brookes


In 1973, Brookes and Green1 first introduced the principles of the’ soft’ impressor technique by using copper cones to deform (001) surfaces of single crystal magnesium oxide (MgO). They employed an etch pit technique2 to show that, for otherwise identical experimental conditions, the mean contact pressure (Pm) due to the blunted copper cone (i. e. about 0.53 GPa) did not form a visible impression but, nevertheless, produced a dislocated volume in the bulk of the crystal which was about the same size as that due to a diamond (Knoop) indenter where the mean contact pressure was about 6 GPa. Thus, it was established that hard crystalline solids could be plastically deformed by contact with softer materials at pressures of at least one order of magnitude less than the relevant measured hardness value. In addition, they suggested that cumulative deformation, as in repeated sliding over the same track, could lead to the mechanical wear of hard materials by softer ones. Those earlier suggestions have been investigated and verified for magnesium oxide and a wider range of crystals at room temperature3–10 and for diamond at elevated temperatures11–16.


Contact Pressure Slip System Slip Plane Resolve Shear Stress Critical Resolve Shear Stress 
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  1. 1.
    C.A. Brookes and P. Green, Deformation of magnesium oxide crystals by softer indenters and sliders, Nature, 246:119 (1973).ADSCrossRefGoogle Scholar
  2. 2.
    R. Stokes, T. C. Johnston and C. H. Li, Crack formation in magnesium oxide single crystals, Phil Mag., 3:718 (1958).ADSCrossRefGoogle Scholar
  3. 3.
    C. A. Brookes, M. P. Shaw and P. E. Tanner, Non-metallic crystals undergoing cumulative work-hardening and wear due to softer lubricated metal sliding surfaces, Proc. Roy. Soc. Lond., A409:141 (1987).ADSGoogle Scholar
  4. 4.
    C. A. Brookes, A review of the role of plastic flow in the process of indentation and wear in ceramic crystals, J. Aust. Ceram. Soc., 24:116 (1988).Google Scholar
  5. 5.
    C. A. Brookes and M. P. Shaw, Cumulative deformation of magnesium oxide crystals by softer sliders, Nature, 263:760 (1976).ADSCrossRefGoogle Scholar
  6. 6.
    M. P. Shaw and C. A. Brookes, Cumulative deformation and fracture of sliding surfaces, Wear, 126:149 (1988).CrossRefGoogle Scholar
  7. 7.
    M. P. Shaw and C. A. Brookes, Dislocations produced in magnesium oxide crystals due to contact pressures developed by softer cones, J. Mats. Sci., 24:2727 (1989)ADSCrossRefGoogle Scholar
  8. 8.
    C. A. Brookes, R. M. Hooper and J. E. Morgan, Some factors influencing indentation creep in crystalline solids, “European Applied Research Reports,” ed., Hj Matzke, Harwood Academic Publishers, 7:1127 (1987).Google Scholar
  9. 9.
    C. A. Brookes, E. J. Brookes and G. Xing, The use of the soft indenter technique to investigate impression creep in ceramic crystals, “Mechanics of Creep Brittle Materials 2,” eds., A. C. F. Cocks and A. R. S. Ponter, Elsevier, London, (1991)Google Scholar
  10. 10.
    C. A. Brookes, E. J. Brookes and L. Y. Zhang, The cumulative deformation, work-hardening and fracture of magnesium oxide at room temperature, under repeated point loading conditions, Proceedings of this conference.Google Scholar
  11. 11.
    C. A. Brookes, V. R. Howes and A. R. Parry, Multiple slip in diamond due to a nominal contact pressure of 10 GPa at 1000°C, Nature, 332:139 (1988).ADSCrossRefGoogle Scholar
  12. 12.
    C. A. Brookes, E. J. Brookes, V. R. Howes, S. G. Roberts and C. P. Waddington, A comparison of the plastic deformation and creep of types I, type II and synthetic diamonds at 1100°C under conditions of point loading, J. Hard Mats., 1:183 (1990).Google Scholar
  13. 13.
    C. A. Brookes and A. R. Parry, Some fundamental aspects of the mechanical wear of hard ceramics due to sliding, Materials Science and Engineering, A105/106:143 (1988).Google Scholar
  14. 14.
    E. J. Brookes, “The Plasticity of Diamond”, PhD dissertation, University of Hull, (1992).Google Scholar
  15. 15.
    E. J. Brookes, A. T. Collins and G. S. Woods, Cathodoluminescence at indentations in diamonds, J. Hard Mats., 4:997 (1993).Google Scholar
  16. 16.
    C. A. Brookes, Indentation hardness, plasticity and creep of diamond, in: “The Properties of Natural and Synthetic Diamond, J. E. Field, ed., Academic Press, London, (1992).Google Scholar
  17. 17.
    D. Tabor and J. E. Field, Friction of diamond, in: “The Properties of Natural and Synthetic Diamond, J. E. Field, ed., Academic Press, London, (1992).Google Scholar
  18. 18.
    C. A. Brookes, J. B. O’Niell and B. A. W. Redfern, Anisotropy in the hardness of single crystals, Proc. Roy. Soc. Lond., A322:73 (1971).ADSGoogle Scholar
  19. 19.
    P. B. Hirsch, P. Pirouz, S. G. Roberts and P. D. Warren, Indentation plasticity and polarity of hardness on 111 faces of GaAs. Phil. Mag. B, 52: 759–784 (1985).ADSCrossRefGoogle Scholar
  20. 20.
    S. G. Roberts, P. D. Warren and P. B. Hirsch, Knoop hardness anisotropy on 001 faces of germanium and gallium arsenide, J. Mats. Res., 1:162–176 (1986).ADSCrossRefGoogle Scholar
  21. 21.
    A.E.H. Love, The stress produced in a semi-infinite solid by pressure on part of the boundary, Proc. Roy. Soc. Lond., A228: 377–420 (1929).ADSGoogle Scholar
  22. 22.
    G. W. Groves and A. Kelly, The dislocation distribution in plastically deformed magnesium oxide, Proc. Roy. Soc. Lond., A275:233 (1963).ADSGoogle Scholar
  23. 23.
    A. D. Keh, J. C. M. Li and Y. T. Chou., Cracks due to the piling up of dislocations on two intersecting slip planes in MgO crystals, Acta Metall, 7:695 (1959).Google Scholar
  24. 24.
    C. A. Brookes and J. D. J. Ross, Direct evidence of reversed plastic flow around indentations in magnesium oxide, “European Applied Research Reports, ed., Hj Matzke, Harwood Academic Publishers, 7:1147 (1987).Google Scholar
  25. 25.
    A.G. Atkins, A. Silverio and D. Tabor, Indentation hardness and creep of solids, J. Inst. Metals, 94:369 (1966).Google Scholar
  26. 26.
    P. M. Sargent and M. F. Ashby, CUED/C Mats., TR. 145 (1989).Google Scholar
  27. 27.
    W. B. Li, J. L. Henshall, R. M. Hooper and K. E. Easterling, The mechanism of indentation creep, Acta Metall. Mater., 39:3099 (1991).CrossRefGoogle Scholar
  28. 28.
    J. E. Field, Strength, fracture and erosion properties of diamond, in: “The Properties of Natural and Synthetic Diamond”, J. E. Field, ed., Academic Press, London, (1992).Google Scholar
  29. 29.
    C. D. Clark, E. W. Mitchell and B. J. Parsons, Colour centres and optical properties, in: “The Properties of Diamond”, J. E. Field, ed., Academic Press, London, (1976).Google Scholar
  30. 30.
    C. D. Clark, A. T. Collins and G. S. Woods, Absorption an luminescence spectroscopy, in: “The Properties of Natural and Synthetic Diamond”, J. E. Field, ed., Academic Press, London, (1992).Google Scholar
  31. 31.
    V. I. Trefilov, Yu V. Mil’man and O. N. Grigor’ev, Deformation and rupture of crystals with covalent interatomic bonds, J. of Crystal Growth and Char act., 16:225–277 (1988).CrossRefGoogle Scholar
  32. 32.
    S. Fujita, K. Maeda and S. Hoyodo, Dislocation glide motion in 6H SiC single crystals subjected to high temperature deformation, Phil Mag, A55(2):203 (1987).ADSGoogle Scholar
  33. 33.
    V. R. Howes and S. Tolansky, Proc. Roy Soc. Lond., A23O:287, ibid: 294 (1955).Google Scholar
  34. 34.
    P. Pirouz, R. Chaim, V. Dahamen and K.H. Westmacott, The Martensitic Transformation in Silicon: 1. Experimental Observations. Acta. Met., 38(2):313–337 (1990).CrossRefGoogle Scholar
  35. 35.
    N. V. Novikov and S. N. Dub, Fracture toughness of diamond single crystals, J. Hard Mater., 2:3 (1991).Google Scholar
  36. 36.
    C. A. Brookes, A process for modifying the surface of hard engineering ceramic materials, International Patent: WO 89/04239, US: 5128083.Google Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • E. Jill Brookes
    • 1
  • Chris A. Brookes
    • 1
  1. 1.Department of Engineering Design and ManufactureUniversity of HullHullUK

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