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.
| Language | English (US) |
|---|---|
| Pages | 908-931 |
| Number of pages | 24 |
| Journal | Philosophical Magazine |
| Volume | 91 |
| Issue number | 6 |
| DOIs | |
| State | Published - Feb 21 2011 |
| Externally published | Yes |
Profile
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 journal › Article
}
TY - JOUR
T1 - Control of dynamic recovery and strength by subgrain boundaries - Insights from stress-change tests on CaF2 single crystals
AU - Mekala,S.
AU - Eisenlohr,P.
AU - Blum,W.
PY - 2011/2/21
Y1 - 2011/2/21
N2 - 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.
AB - 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.
KW - boundary migration
KW - creep
KW - crystal defects
KW - deformation mechanisms
KW - dislocation interactions
KW - dislocation structures
KW - mechanical properties
KW - plasticity of crystals
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UR - http://www.scopus.com/inward/citedby.url?scp=79951518919&partnerID=8YFLogxK
U2 - 10.1080/14786435.2010.535324
DO - 10.1080/14786435.2010.535324
M3 - Article
VL - 91
SP - 908
EP - 931
JO - Philosophical Magazine
T2 - Philosophical Magazine
JF - Philosophical Magazine
SN - 1478-6435
IS - 6
ER -