Experimental Mechanics

, Volume 53, Issue 8, pp 1299–1309 | Cite as

Effect of Varying Test Parameters on Elastic–plastic Properties Extracted by Nanoindentation Tests

  • L. Ladani
  • E. Harvey
  • S. F. Choudhury
  • C. R. Taylor


A systematic experiment was performed in an effort to investigate how the levels of certain test parameters affect the values of elastic modulus, hardness, yield stress, and strain hardening constant obtained using nanoindentation test. Maximum applied load, loading (unloading) rate, and hold time at maximum load were varied at three levels. The effects of these testing parameters were investigated through a three-level, full factorial design of experiment. The experiments were conducted on ultrafine Al-Mg specimens that were mechanically extruded. Both longitudinal and transverse extrusion directions were examined to investigate effects of anisotropy on mechanical properties and evaluate the persistence of observed variations due to test parameters on different materials orientations. An indentation size effect (ISE) was observed demonstrating that maximum load—and thereby maximum indentation depth—can have a significant effect on values of hardness and elastic modulus. Hardness values decreased with higher loading rates, and higher rates of unloading resulted in higher values of elastic modulus (5–10 GPa increases). Strain-hardening exponent showed a decreasing trend with increasing loading rate while yield stress exhibited a consistent correlation to hardness across all studied parameters. The material exhibited very little creep during the hold period, and values of the calculated properties were not significantly altered by varying the length of the hold time. Anisotropy effect was observed, particularly in the values of yield strength. This is attributed to the preferred grain orientation due to extrusion.


Nanoindentation Ultrafine grain Plastic behavior Al-Mg Strain hardening exponent Yield strength Hardness p-h curve 



The authors would like to acknowledge the National Science Foundation for support of this research. This material is based upon work supported by the National Science Foundation under Grant No. 1053434. This work used resources in the Center for Materials for Information Technology which is supported by The University of Alabama.


  1. 1.
    Fischer-Cripps, Anthony C (2002) Nanoindentation. Springer-Verlag New York, Inc., New YorkCrossRefGoogle Scholar
  2. 2.
    Doerner MF, Nix WD (1986) A method for interpreting the data from depth-sensing instruments. J Mater Res 1:601–609CrossRefGoogle Scholar
  3. 3.
    Oliver WC, Pharr GM (1992) An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J Mater Res 7:1564–1583CrossRefGoogle Scholar
  4. 4.
    Dao M, Chollacoop N, Van Vliet KJ, Venkatesh TA, Suresh A (2001) Computational modeling of the forward and reverse problems in instrumented sharp indentation. Acta Mater 49:3899–3918CrossRefGoogle Scholar
  5. 5.
    Huang Y, Liu X, Zhou Y, Ma Z, Lu C (2011) Mathematical analysis on the uniqueness of reverse algorithm for measuring elastic–plastic properties by sharp indentation. J Mater Sci Technol 27:577–584CrossRefGoogle Scholar
  6. 6.
    Ogasawara N, Chiba N, Chen X (2006) Measuring the plastic properties of bulk materials by single indentation test. Scr Mater 54:65–70CrossRefGoogle Scholar
  7. 7.
    Das CR, Dhara S, Jeng Y, Tsai C, Hsu HC, Raj B, Bhaduri AK, Albert SK, Tyagi AK, Chen LC, Chen KH (2010) Direct observation of amophization in load rate dependent nanoindentation studies of crystalline Si. Appl Phys Lett 96:253113CrossRefGoogle Scholar
  8. 8.
    Wu Z, Baker TA, Ovaert TC, Niebur GL (2011) The effect of holding time on nanoindentation measurements of creep in bone. J Biomech 44:1066–1072CrossRefGoogle Scholar
  9. 9.
    Chudoba T, Richter F (2001) Investigation of creep behavior under load during indentation experiments and its influence on hardness and modulus results. Surf Coat Technol 148:191–198CrossRefGoogle Scholar
  10. 10.
    Goodall R, Clyne TW (2006) A critical appraisal of the extraction of creep parameters from nanoindentation data obtained at room temperature. Acta Mater 54:5489–5499CrossRefGoogle Scholar
  11. 11.
    Nohava J, Randall NX, Conté N (2009) Novel ultra nanoindentation method with extremely low thermal drift: principle and experimental results. J Mater Res 24:873–882CrossRefGoogle Scholar
  12. 12.
    Mayo MJ, Siegel RW, Narayanasamy A, Nix WD (1990) Mechanical properties of nanophase TiO2 as determined by nanoindentation. J Mater Res 5:1073–1082CrossRefGoogle Scholar
  13. 13.
    Burgess T, Laws KJ, Ferry M (2008) Effect of loading rate on the serrated flow of bulk metallic glass during nanoindentation. Acta Mater 56:4829–4835CrossRefGoogle Scholar
  14. 14.
    Amini A, He Y, Sun Q (2011) Loading rate dependency of maximum nanoindentation in nano-grained NiTi shape memory alloy. Mater Lett 65:464–466CrossRefGoogle Scholar
  15. 15.
    Nix WD, Gao H (1998) Indentation size effects in crystalline materials: a law for strain gradient plasticity. J Mech Phys Solids 46:411–425CrossRefzbMATHGoogle Scholar
  16. 16.
    Mayo MJ, Nix WD (1988) A micro-indentation study of superplasticity in Pb, Sn, and Sn-38 wt% Pb. Acta Metall 36:2183–2192CrossRefGoogle Scholar
  17. 17.
    Maier V, Durst K, Mueller J, Backes B, Höppel HW, Göken M (2011) Nanoindentation strain-rate jump tests for determining the local strain-rate sensitivity in nanocrystalline Ni and ultrafine-grained Al. J Mater Res 26:1421–1430CrossRefGoogle Scholar
  18. 18.
    Harvey E, Ladani L, and Weaver M (2012) “Complete Mechanical Characterization of Nanocrystalline Al-Mg Alloy Using Nanoindentation,” Mech Mater 52:1–11. doi: 10.1016/j.mechmat.2012.04.005
  19. 19.
    Manika I, Maniks J (2006) Size effects in micro- and nanoscale indentation. Acta Mater 56:2049–2056CrossRefGoogle Scholar
  20. 20.
    Zong Z, Lou J, Adewoye OO, Elmustafa AA, Hammad F, Soboyejo WO (2006) Indentation size effects in the nano- and micro-hardness of FCC single crystal metals. Mater Sci Eng, A 434:178–187CrossRefGoogle Scholar
  21. 21.
    Elmustafa AA, Eastman JA, Rittner MN, Weertman JR, Stone DS (2000) Indentation size effect: large grained aluminum versus nanocrystalline aluminum-zirconium alloys. Scr Mater 43:951–955CrossRefGoogle Scholar
  22. 22.
    Durst K, Bakes B, Goken M (2005) Indentation size effect in metallic materials: correcting for the size of the plastic zone. Scr Mater 52:1093–1097CrossRefGoogle Scholar
  23. 23.
    Han L, Hu H, Northwood DO, and Li N (2008) “Microstructure and nanoscale mechanical behavior of Mg-Al and Mg-Al-Ca Alloys” Mater Sci Eng A 473: 16–27Google Scholar
  24. 24.
    Li J, Li F, Xue F, Cai J, and Chen B (2012) “Micromechanical behavior study of forged 7050 aluminum alloy by microindentation” Mater Des 37: 491–499Google Scholar
  25. 25.
    Xue F, Li F, Cai J, Yuan Z, Chen B, Liu T (2012) Characterization of the elasto-plastic properties of 0Cr12Mn5Ni4Mo3Al steel by microindentation. Sustain Mater Des Appl 36:81–87Google Scholar
  26. 26.
    Bolshakov A and Pharr G (1998) “Influences of pileup on the measurement of mechanical properties by load and depth sensing indentation techniques”, J Mater Res 13(4): 1049–1058Google Scholar
  27. 27.
    Giannakopoulos A and Suresh S (1999) “Determination Of elastoplastic properties by instrumented sharp indentation” Scr Mater 40(10): 1191–1198Google Scholar
  28. 28.
    Tabor D (1951) The hardness of metals. Oxford University Press Inc., New YorkGoogle Scholar
  29. 29.
    Ahn B, Mitra R, Lavernia EJ, Nutt SR (2010) Effect of grain size on strain rate sensitivity of cryomilled Al-Mg alloy. J Mater Sci 45:4790–4795CrossRefGoogle Scholar
  30. 30.
    Ahn B, Mitra R, Hodge AM, Lavernia EJ, Nutt SR (2008) Strain rate sensitivity studies of cryomilled Al alloy performed by nanoindentation. Mater Sci Forum 584–586:221–226CrossRefGoogle Scholar
  31. 31.
    Vlassak JJ, Nix WD (1993) “Indentation modulus of elastically anisotropic half spaces,” Phil Mag A 67:1045–1056Google Scholar
  32. 32.
    Vlassak JJ, Nix WD (1994) “Measuring the elastic properties of anisotropic materials by means of indentation experiments. J Mech Phys Solids 42:1223CrossRefGoogle Scholar
  33. 33.
    Han B, Lee Z, Witkin D, Nutt S, and Lavernia E (2005) “Deformation Behavior of Bimodal Nanostructured 5083 Al Alloys” Metall Mater Trans A 36: 957Google Scholar
  34. 34.
    Joshi S, Ramesh K, Han B and Lavernia E (2006) “Modeling the Constitutive Response of Bimodal Metals”, Metall Mater Trans A 37: 2397–2404Google Scholar
  35. 35.
    Magee A, Ladani L, Topping T and Lavernia E (2012) “Effects of tensile test parameters on the mechanical properties of a bimodal Al–Mg alloy,” Acta Mater 60: 5838–5849Google Scholar
  36. 36.
    Fjeldly A, Roven HJ (1996) Observation and calculation of mechanical anisotropy and plastic flow of AlMgZn extrusion. Acta Mater 44(9):3497–3504CrossRefGoogle Scholar

Copyright information

© Society for Experimental Mechanics 2013

Authors and Affiliations

  • L. Ladani
    • 1
  • E. Harvey
    • 1
  • S. F. Choudhury
    • 1
  • C. R. Taylor
    • 2
  1. 1.Department of Mechanical EngineeringUniversity of AlabamaTuscaloosaUSA
  2. 2.Department of Mechanical and Aerospace EngineeringUniversity of FloridaGainesvilleUSA

Personalised recommendations