Subsurface shear instability and nanostructuring of metals in sliding

S. Tarasov, V. Rubtsov, A. Kolubaev

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Dry sliding wear conditions were used to obtain a 500 μm-thick layer of nanosize grains on copper samples. As shown, this layer reveals a flow behavior pattern similar to that of a viscous non-Newtonian fluid. Four structurally different zones were found in the longitudinal cross-sections of samples below the worn surface. Upper two of them are nanocrystalline and consist of many ∼1 μm-thick sublayers, which show either laminar or turbulent flow behavior. These sublayers demonstrate different levels of elasticity as compared to each other and may be related to an interplay between work-hardening and thermal softening. Lower two zones undergo usual plastic deformation and severe fragmentation without viscous mass transfer. High level of Young's modulus in the fragmentation zone is evidence of insufficient thermal softening at that depth. We believe that viscous flow zones are the result of shear instability and subsequent shear deformation developed in subsurface layers due to thermal softening. Numerical study has been carried out to simulate friction-induced deformation and shear instability under conditions close to the experiment. As shown, such a situation is possible when deformation-generated heat is taken into account. Another interesting result relates to the sublayers' strain rate distribution. It was found that 1 μm-thick sublayers may show either high strain rate gradient or zero strain rate as a function of depth below the worn surface. The latter case means that a pack of layers may exist and behave like an elastic body in ductile medium.

Original languageEnglish
Pages (from-to)59-66
Number of pages8
JournalWear
Volume268
Issue number1
DOIs
Publication statusPublished - 4 Jan 2010
Externally publishedYes

Fingerprint

sliding
Metals
softening
shear
strain rate
Strain rate
metals
fragmentation
elastic bodies
work hardening
viscous flow
Viscous flow
laminar flow
Laminar flow
Strain hardening
turbulent flow
Shear deformation
Turbulent flow
plastic deformation
mass transfer

Keywords

  • Nanostructuring
  • Numerical simulation
  • Shear instability
  • Sliding
  • Strain localization
  • Viscous flow

ASJC Scopus subject areas

  • Mechanics of Materials
  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Subsurface shear instability and nanostructuring of metals in sliding. / Tarasov, S.; Rubtsov, V.; Kolubaev, A.

In: Wear, Vol. 268, No. 1, 04.01.2010, p. 59-66.

Research output: Contribution to journalArticle

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