Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The conflicts between strength and toughness


The attainment of both strength and toughness is a vital requirement for most structural materials; unfortunately these properties are generally mutually exclusive. Although the quest continues for stronger and harder materials, these have little to no use as bulk structural materials without appropriate fracture resistance. It is the lower-strength, and hence higher-toughness, materials that find use for most safety-critical applications where premature or, worse still, catastrophic fracture is unacceptable. For these reasons, the development of strong and tough (damage-tolerant) materials has traditionally been an exercise in compromise between hardness versus ductility. Drawing examples from metallic glasses, natural and biological materials, and structural and biomimetic ceramics, we examine some of the newer strategies in dealing with this conflict. Specifically, we focus on the interplay between the mechanisms that individually contribute to strength and toughness, noting that these phenomena can originate from very different lengthscales in a material's structural architecture. We show how these new and natural materials can defeat the conflict of strength versus toughness and achieve unprecedented levels of damage tolerance within their respective material classes.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Conflicts of strength versus toughness.
Figure 2: Strength and toughness strategies for BMG alloys.
Figure 3: Extrinsic toughening in monolithic ceramics.
Figure 4: The structure of bone showing the seven levels of hierarchy with the prevailing toughening mechanisms.
Figure 5: Toughening in mollusc shells (nacre) and in corresponding biomimetic ceramics.


  1. Olson, G. B. & Cohen, M. in Dislocations in Solids Vol. 7 (ed. Nabarro, F. R. N.) Ch. 37, 295–407 (North-Holland, 1986).

    Google Scholar 

  2. Gupta, H. S. et al. Nanoscale deformation mechanisms in bone. Nano Lett. 5, 2108–2111 (2005).

    Article  CAS  Google Scholar 

  3. Wang, R. Z. et al. Deformation mechanisms in nacre. J. Mater. Res. 16, 2485–2493 (2001).

    Article  CAS  Google Scholar 

  4. Vashishth, D. Rising crack-growth-resistance behavior in cortical bone: Implication for toughness measurements. J. Biomech. 37, 943–946 (2003).

    Article  Google Scholar 

  5. Conner, R. D. et al. Shear bands and cracking of metallic glass plates in bending. J. Appl. Phys. 94, 904–911 (2003).

    Article  CAS  Google Scholar 

  6. Evans, A. G. Perspective on the development of high-toughness ceramics. J. Am. Ceram. Soc. 73, 187–206 (1990).

    Article  CAS  Google Scholar 

  7. Ritchie, R. O. Mechanisms of fatigue crack-propagation in metals, ceramics and composites: Role of crack tip shielding. Mater. Sci. Eng. A 103, 15–28 (1988).

    Article  Google Scholar 

  8. Launey, M. E. & Ritchie, R. O. On the fracture toughness of advanced materials. Adv. Mater. 21, 2103–2110 (2009).

    Article  CAS  Google Scholar 

  9. Hoffman, D. C. et al. Designing metallic glass matrix composites with high toughness and tensile ductility. Nature 451, 1085–1090 (2008).

    Article  Google Scholar 

  10. Launey, M. E. et al. Fracture toughness and crack resistance curve behavior in metallic glass matrix composites. Appl. Phys. Lett. 94, 241910 (2009).

    Article  Google Scholar 

  11. Demetriou, M. et al. A damage-tolerant glass. Nature Mater. 10, 123–128 (2011).

    Article  CAS  Google Scholar 

  12. Gilbert, C. J. et al. Crack-growth resistance-curve behavior in silicon carbide: Small versus long cracks J. Am. Ceram. Soc. 80, 2253–2261 (1997).

    Article  CAS  Google Scholar 

  13. Clarke, D. R. & Thomas, G. Microstructures of Y2O3 fluxed hot-pressed silicon nitride. J. Am. Ceram. Soc. 60, 491–495 (1978).

    Article  Google Scholar 

  14. Meyers, M. A. et al. Mechanical strength of abalone nacre: Role of the soft organic layer. J. Mech. Behav. Biomed. Mater. 1, 76–85 (2008).

    Article  Google Scholar 

  15. Weiner S. & Wagner H. D. The material bone: Structural-mechanical functional relations. Ann. Rev. Mater. Sci. 28, 271–298 (1998).

    Article  CAS  Google Scholar 

  16. Aizenberg, J. & Fratzl, P. Biological and biomimetic materials. Adv. Mater. 21, 387–388 (2009).

    Article  CAS  Google Scholar 

  17. Ortiz, C. & Boyce, M. C. Materials science - Bioinspired structural materials. Science 319, 1053–1054 (2008).

    Article  CAS  Google Scholar 

  18. Launey, M. E., Buehler, M. J. & Ritchie R. O. On the mechanistic origins of toughness in bone. Ann. Rev. Mater. Res. 40, 25–53 (2010).

    Article  CAS  Google Scholar 

  19. Bailey, A. J. Molecular mechanisms of ageing in connective tissues. Mech. Ageing Dev. 122, 735–755 (2001).

    Article  CAS  Google Scholar 

  20. Nalla, R. K., Kinney, J. H. & Ritchie, R. O. Mechanistic fracture criteria for the failure of human cortical bone. Nature Mater. 2, 164–168 (2003).

    Article  CAS  Google Scholar 

  21. Koester, K. J., Ager, J. W. III & Ritchie, R. O. How tough is human bone? In situ measurements on realistically short cracks. Nature Mater. 7, 672–677 (2008).

    Article  CAS  Google Scholar 

  22. Sarikaya, M. & Aksay, I. A. in Results and Problems in Cell Differentiation Vol. 19 (ed. Case, S.) Ch. 1 (Springer, 1992).

    Google Scholar 

  23. Mayer, G. New classes of tough composite materials - Lessons from natural rigid biological systems. Mater. Sci. Eng. C 26, 1261–1268 (2006).

    Article  CAS  Google Scholar 

  24. Barthelat, F. & Espinosa, H. D. An experimental investigation of deformation and fracture of nacre-mother of pearl. Exp. Mech. 47, 311–324 (2007).

    Article  Google Scholar 

  25. Munch, E. et al. Tough, bio-inspired hybrid materials. Science 322, 1516–1520 (2008).

    Article  CAS  Google Scholar 

  26. Deville, S., Saiz, E., Nalla, R. K. & Tomsia, A. P. Freezing as a path to build complex composites. Science 311, 515–518 (2006).

    Article  CAS  Google Scholar 

Download references


This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Particular thanks to A. P. Tomsia and E. Launey for their help with this paper.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Robert O. Ritchie.

Ethics declarations

Competing interests

The author declares no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Ritchie, R. The conflicts between strength and toughness. Nature Mater 10, 817–822 (2011).

Download citation

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing