Abstract
In order to investigate the mechanism behind the improvement of fracture toughness in ultrafinegrained metals at low temperatures, the strain rate dependence of the transition of dislocationsources from crack tips to grain boundaries is studied by the combination of molecular dynamicssimulations and the linear elastic theory. As the strain rate decreases, grain boundaries becomeanother stress consented site due to the pile-up of dislocations against the grain boundaries. Theamount of stress concentration became larger than that of crack tip as the number of dislocationsemitted from the crack tip increases. It was clearly indicated that dislocations were impinged intothe grain boundary when a new dislocation was emitted from there. It indicates the transition ofdislocation sources from the crack tip to grain boundaries at lower applied stresses. The distributionof dislocations between the crack tip and grain boundary is strongly related to the strain rate ; namely, a larger number of dislocations are distributed very close to the crack tip as the strain rate increases.It induces the smaller stress concentration at the grain boundary since the number of piling-updislocations is decreased around the grain boundary. Consequently, as the strain rate increases, thematerial becomes brittle, indicating that it will fail in a brittle mode and no longer deform plastically.
| Original language | English |
|---|---|
| Pages (from-to) | 169-174 |
| Number of pages | 6 |
| Journal | Zairyo/Journal of the Society of Materials Science, Japan |
| Volume | 61 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb 1 2012 |
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
Cite this
Strain rate dependence of the transition of dislocation sources from crack tips to grain boundaries based on the development of internal defect's stress field. / Shimokawa, Tomotsugu; Tanaka, Masaki; Higashida, Kenji.
In: Zairyo/Journal of the Society of Materials Science, Japan, Vol. 61, No. 2, 01.02.2012, p. 169-174.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Strain rate dependence of the transition of dislocation sources from crack tips to grain boundaries based on the development of internal defect's stress field
AU - Shimokawa, Tomotsugu
AU - Tanaka, Masaki
AU - Higashida, Kenji
PY - 2012/2/1
Y1 - 2012/2/1
N2 - In order to investigate the mechanism behind the improvement of fracture toughness in ultrafinegrained metals at low temperatures, the strain rate dependence of the transition of dislocationsources from crack tips to grain boundaries is studied by the combination of molecular dynamicssimulations and the linear elastic theory. As the strain rate decreases, grain boundaries becomeanother stress consented site due to the pile-up of dislocations against the grain boundaries. Theamount of stress concentration became larger than that of crack tip as the number of dislocationsemitted from the crack tip increases. It was clearly indicated that dislocations were impinged intothe grain boundary when a new dislocation was emitted from there. It indicates the transition ofdislocation sources from the crack tip to grain boundaries at lower applied stresses. The distributionof dislocations between the crack tip and grain boundary is strongly related to the strain rate ; namely, a larger number of dislocations are distributed very close to the crack tip as the strain rate increases.It induces the smaller stress concentration at the grain boundary since the number of piling-updislocations is decreased around the grain boundary. Consequently, as the strain rate increases, thematerial becomes brittle, indicating that it will fail in a brittle mode and no longer deform plastically.
AB - In order to investigate the mechanism behind the improvement of fracture toughness in ultrafinegrained metals at low temperatures, the strain rate dependence of the transition of dislocationsources from crack tips to grain boundaries is studied by the combination of molecular dynamicssimulations and the linear elastic theory. As the strain rate decreases, grain boundaries becomeanother stress consented site due to the pile-up of dislocations against the grain boundaries. Theamount of stress concentration became larger than that of crack tip as the number of dislocationsemitted from the crack tip increases. It was clearly indicated that dislocations were impinged intothe grain boundary when a new dislocation was emitted from there. It indicates the transition ofdislocation sources from the crack tip to grain boundaries at lower applied stresses. The distributionof dislocations between the crack tip and grain boundary is strongly related to the strain rate ; namely, a larger number of dislocations are distributed very close to the crack tip as the strain rate increases.It induces the smaller stress concentration at the grain boundary since the number of piling-updislocations is decreased around the grain boundary. Consequently, as the strain rate increases, thematerial becomes brittle, indicating that it will fail in a brittle mode and no longer deform plastically.
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U2 - 10.2472/jsms.61.169
DO - 10.2472/jsms.61.169
M3 - Article
VL - 61
SP - 169
EP - 174
JO - Zairyo/Journal of the Society of Materials Science, Japan
JF - Zairyo/Journal of the Society of Materials Science, Japan
SN - 0514-5163
IS - 2
ER -