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An Examination of the Indentation Size Effect and Bi-Linear Behavior of FCC Metals

Published online by Cambridge University Press:  10 February 2012

D.E. Stegall ,
B. Crawford  and
A.A. Elmustafa
D.E. Stegall
Affiliation:
Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, 23529, United States
B. Crawford
Affiliation:
Nanomechanics Inc, Oak Ridge, TN, 37830
A.A. Elmustafa
Affiliation:
Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, 23529, United States
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Abstract

We investigated pure FCC metals including Aluminum, Nickel, Silver, and 70/30 Copper Zinc (alpha-brass) alloy for the indentation size effect (ISE) and the bilinear behavior using a single Berkovich indenter tip in a single test machine. The results were consistent with those reported by Elmustafa and Stone, 2003 of the ISE and the bilinear behavior using two separate indenter tips (Berkovich and Vickers) from two separate machines. This behavior is mechanistic in nature and is observed regardless of the type of the self similar indenter tip employed. Furthermore, the research presented in this paper would seem to also validate the conclusions that Elmustafa et al (2004) articulate that the Strain Gradient Plasticity collapses at small scales and that the bilinear behavior of these FCC metals is attributed to the presence of long range shear stresses induced by geometrically necessary dislocations. Also, we observed what has been defined as a “tapping” issue for materials with high E/H ratios when using the CSM. The CSM protocol results in erroneous hardness results at very shallow depths for high E/H ratio soft metals due to the so called “tapping” of the stylus as articulated by Pharr et al. (2009). This method should only be used as a secondary technique to the load control protocol when examining the ISE effect.

Keywords

dislocationshardnessnano-indentation
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1424: Symposium SS – Properties and Processes at the Nanoscale Nanomechanics of Material Behavior , 2012 , mrsf11-1424-ss07-55
Copyright
Copyright © Materials Research Society 2012

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References

1. Tabor, D., The Hardness of Metals. Journal of the Institue of Metals, 1951. 79: p. 67–76.Google Scholar
2. Nabarro, F.R.N., Shrivastava, S., and Luyckx, S.B., The size effect in microindentation. Philosophical Magazine, 2006. 86: p. 4173–4180.Google Scholar
3. Poole, W.J., Ashby, M.F., and Fleck, N.A., Micro-hardness of annealed and work-hardened copper polycrystals. Scripta Materialia, 1996. 34: p. 559–64.Google Scholar
4. Fleck, N.A., et al. ., Strain gradient plasticity: theory and experiment. Acta Metallurgica et Materialia, 1994. 42: p. 475–87.Google Scholar
5. Gao, H., et al. ., Mechanism-based strain gradient plasticity - I. Theory. Journal of the Mechanics and Physics of Solids, 1999. 47: p. 1239–1263.Google Scholar
6. Huang, Y., et al. ., Mechanism-based strain gradient plasticity. II. Analysis. Journal of the Mechanics and Physics of Solids, 2000. 48: p. 99–128.Google Scholar
7. Ma, Q. and Clarke, D.R., Size dependent hardness of silver single crystals. Journal of Materials Research, 1995. 10(Compendex): p. 853–863.Google Scholar
8. Nix, W.D., Gao, H., Indentation Size Effects in crysatlline materials: A law for strain gradient plasticity. Journal of the Mechanics and Physics of Solids, 1998. 46: p. 411–425.Google Scholar
9. Kim, J.-Y., et al. ., Evaluating plastic flow properties by characterizing indentation size effect using a sharp indenter. Acta Materialia, 2008. 56: p. 3338–3343.Google Scholar
10. Zong, Z., et al. ., Indentation size effects in the nano and microhardness of FCC single crystal metals. Materials and Manufacturing Processes, 2007. 22(Compendex): p. 228–237.Google Scholar
11. Elmustafa, A.A. and Stone, D.S., Nanoindentation and the indentation size effect: Kinetics of deformation and strain gradient plasticity. Journal of the Mechanics and Physics of Solids, 2003. 51: p. 357–81.Google Scholar
12. Elmustafa, A.A., Ananda, A.A., and Elmahboub, W.M., Bilinear behavior in nano and microindentation tests of fcc polycrystalline materials. Journal of Engineering Materials and Technology, Transactions of the ASME, 2004. 126: p. 353–359.Google Scholar
13. Stegall, D.E., Crawford, B, Elmustafa, A.A., Indentation Size Effect in FCC Metals: An Examination of Experimental Techniques and the Bi-Linear Behavior. Journal of Materials Research, (In Review).Google Scholar
14. Oliver, W.C. and Pharr, G.M., An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. Journal of Materials Research, 1992. 7: p. 1564–83.Google Scholar
15. Pharr, G.M., Strader, J.H., and Oliver, W.C., Critical issues in making small-depth mechanical property measurements by nanoindentation with continuous stiffness measurement. Journal of Materials Research, 2009. 24: p. 653–66.Google Scholar
16. Pharr, G.M., Herbert, E.G., and Yanfei, G., The Indentation Size Effect: A Critical Examination of Experimental Observations and Mechanistic Interpretations. Annual Review of Materials Research, 2010. 40: p. 271–92.Google Scholar