Nanoindentation Response Analysis of Thin Film Substrates-II: Strain Hardening-Softening Oscillations in Subsurface Layer
Latvian Journal of Physics and Technical Sciences 2017
Uldis Kanders, Kārlis Kanders

We extracted stress-strain field (SSF) gradient and divergence representations from nanoindentation data sets of bulk solids often used as thin film substrates: bearing and tooling steels, silicon, glasses, and fused silica. Oscillations of the stress-strain field gradient and divergence induced in the subsurface layer by the nanoindentation were revealed. The oscillations were especially prominent in single indentation tests at shallow penetration depths, h<100 nm, whereas they were concealed in the averaged datasets of 10 and more single tests. The amplitude of the SSF divergence oscillations decayed as a sublinear power-law when the indenter approached deeper atomic layers, with an exponent -0.9 for the steel and -0.8 for the fused silica. The oscillations were interpreted as alternating strain hardening-softening cycles induced in the subsurface layer under the indenter load.


Keywords
nanoindentation, subsurface layer, strain gradient plasticity, stress-strain field, elastic-plastic deformation, heterogeneity
DOI
10.1515/lpts-2017-0011

Kanders, U., Kanders, K. Nanoindentation Response Analysis of Thin Film Substrates-II: Strain Hardening-Softening Oscillations in Subsurface Layer. Latvian Journal of Physics and Technical Sciences, 2017, Vol.54, Iss.2, pp.34-45. ISSN 0868-8257. Available from: doi:10.1515/lpts-2017-0011

Publication language
English (en)
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