Abstract
For materials which exhibit a power-law relationship between stress and strain rate, it is theoretically possible to evaluate the exponent (m) which governs the relationship by means of instrumented indentation. However, in practice, tests at small strain rates take so long that the results can easily be dominated by thermal drift. A new test method is developed in which several constant strain rates are examined within a single indentation test by switching strain rates as the indenter continues to move into the material. Switching strain rates within a single test overcomes the problem of long testing times by examining large strain rates first and transitioning to smaller strain rates as the test proceeds. The new method is used to test a sample of fine-grained nickel sold by NIST as a standard reference material for Vickers hardness. The strain-rate sensitivity of this sample is measured to be m = 0.021. This value is in good agreement with values obtained by others on fine-grained nickel using both instrumented indentation and uniaxial creep testing.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
Strictly, the term “indentation strain rate” refers to the displacement rate divided by the displacement (\( \dot{h} \)/h). However, beginning with the definition of hardness, it is easily shown that \( \dot{h} \)/h ≈ 0.5(\( \dot{P} \)/P). Equation 8.2 holds true for either definition of strain rate, because the constant difference between the two definitions (0.5) is simply absorbed into the constant B. Because the Agilent G200 NanoIndenter is a force-controlled instrument, it is logistically easier to control \( \dot{P} \)/P than \( \dot{h} \)/h. Thus, in this work, the term “strain rate” refers to \( \dot{P} \)/P, unless specifically stated otherwise.
References
Lucas BN, Oliver WC (1999) Indentation power-law creep of high-purity indium. Metall Mater Trans A Phys Metall Mater Sci 30(3):601–610
Maier V, Durst K, Mueller J, Backes B, Hoppel H, 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(11):1421–1430
NIST Certificate Standard Reference Material 1896a Vickers Microhardness of Nickel [cited 2011 October 10, 2011]. Available from: http://ts.nist.gov/MeasurementServices/ReferenceMaterials/upload/1896a.pdf
Hay JL, Agee P, Herbert EG (2010) Continuous stiffness measurement during instrumented indentation testing. Exp Tech 34(3):86–94
Shen X, Lian JS, Jiang Z, Jiang Q (2008) High strength and high ductility of electrodeposited nanocrystalline Ni with broad grain size distribution. Mater Sci Eng A487:410
Dalla Torre F, Van Swygenhoven H, Victoria M (2002) Nanocrystalline electrodeposited Ni: microstructure and tensile properties. Acta Mater 50:3957
Dalla Torre F, Spätig P, Schäublin R, Victoria M (2005) Deformation behavior and microstructure of nanocrystalline electrodeposited and high pressure torsioned nickel. Acta Mater 53:2337
Wang YM, Hamza AV, Ma E (2006) Temperature-dependent strain-rate sensitivity and activation volume in nanocrystalline Ni. Acta Mater 54:2715
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2013 The Society for Experimental Mechanics
About this paper
Cite this paper
Hay, J., Maier, V., Durst, K., Göken, M. (2013). Strain-Rate Sensitivity (SRS) of Nickel by Instrumented Indentation. In: Shaw, G., Prorok, B., Starman, L. (eds) MEMS and Nanotechnology, Volume 6. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-4436-7_8
Download citation
DOI: https://doi.org/10.1007/978-1-4614-4436-7_8
Published:
Publisher Name: Springer, New York, NY
Print ISBN: 978-1-4614-4435-0
Online ISBN: 978-1-4614-4436-7
eBook Packages: EngineeringEngineering (R0)