Control of dynamic recovery and strength by subgrain boundaries - Insights from stress-change tests on CaF2 single crystals

S. Mekala, P. Eisenlohr, W. Blum

Research output: Contribution to journalArticle

  • 7 Citations

Abstract

The deformation behavior of single crystals of CaF2 was investigated at homologous temperatures of 0.45 ± 0.05. Stress (σ) changes comprising reductions by a factor up to about 2 were done to separate the dislocation processes. In agreement with previous results for pure Al and LiF, it was found that the response to -reductions in the steady state of deformation starts with a period of declining deformation rate ε̇ before the normal transient reaction with work softening sets in. This first period shrinks significantly when the σ-reduction tests are performed at lower strains, i.e. earlier in the primary transient. Correlation with results for the microstructural evolution during the primary transient allows one to conclude that the transient response with declining ε̇ after σ-reductions is due to subgrain-boundary migration under concentrated stress. The results indicate that dislocation walls in the form of cell and subgrain boundaries control the accumulation of dislocations in strain hardening and that the deformation resistance in steady state reflects the kinetics of subgrain-boundary migration under stress. Consequences for the interpretation of dip tests and stress relaxation tests are discussed.

Original languageEnglish (US)
Pages (from-to)908-931
Number of pages24
JournalPhilosophical Magazine
Volume91
Issue number6
DOIs
StatePublished - Feb 21 2011
Externally publishedYes

Profile

single crystals
work softening
strain hardening
stress relaxation
transient response
recovery
kinetics
cells
temperature

Keywords

  • boundary migration
  • creep
  • crystal defects
  • deformation mechanisms
  • dislocation interactions
  • dislocation structures
  • mechanical properties
  • plasticity of crystals

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Control of dynamic recovery and strength by subgrain boundaries - Insights from stress-change tests on CaF2 single crystals. / Mekala, S.; Eisenlohr, P.; Blum, W.

In: Philosophical Magazine, Vol. 91, No. 6, 21.02.2011, p. 908-931.

Research output: Contribution to journalArticle

Mekala, S.; Eisenlohr, P.; Blum, W. / Control of dynamic recovery and strength by subgrain boundaries - Insights from stress-change tests on CaF2 single crystals.

In: Philosophical Magazine, Vol. 91, No. 6, 21.02.2011, p. 908-931.

Research output: Contribution to journalArticle

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