Effect of grain boundary complexions on the deformation behavior of Ni bicrystal during bending creep

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.

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A Model for the Effects of Strain Rate and Temperature on the Deformation Behavior of Ultrafine-Grained Metals

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.291-294.1173 ◽

2011 ◽

Vol 291-294 ◽

pp. 1173-1177

Author(s):

Zi Ling Xie ◽

Lin Zhu Sun ◽

Fang Yang

Keyword(s):

Grain Boundary ◽

Strain Rate ◽

Deformation Behavior ◽

Boundary Diffusion ◽

Rate Sensitivity ◽

Grain Boundary Sliding ◽

Dislocation Slip ◽

Deformation Response ◽

Ultrafine Grained ◽

Boundary Sliding

A theoretical model is developed to account for the effects of strain rate and temperature on the deformation behavior of ultrafine-grained fcc Cu. Three mechanisms, including dislocation slip, grain boundary diffusion, and grain boundary sliding are considered to contribute to the deformation response simultaneously. Numerical simulations show that the strain rate sensitivity increases with decreasing grain size and strain rate, and that the flow stress and tensile ductility increase with either increasing strain rate or decreasing deformation temperature.

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Temperature Dependence of Compressive Deformation Behavior of Mg89Zn4Y7 Extruded LPSO-Phase Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.607 ◽

2010 ◽

Vol 654-656 ◽

pp. 607-610 ◽

Cited By ~ 6

Author(s):

Koji Hagihara ◽

Akihito Kinoshita ◽

Yuya Sugino ◽

Michiaki Yamasaki ◽

Yoshihito Kawamura ◽

...

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Temperature Dependence ◽

Yield Stress ◽

Deformation Behavior ◽

Grain Boundary Sliding ◽

Deformation Mechanisms ◽

Petch Relationship ◽

Lpso Phase ◽

Boundary Sliding

Deformation mechanisms of Mg89Zn4Y7 (at.%) extruded alloy, which is mostly composed of LPSO-phase, was investigated focusing on their temperature dependence. The yield stress of as-extruded alloy showed extremely high value of ~480 MPa at RT, but it largely decreased to ~130 MPa at 300 °C. The decreasing rate of the yield stress could be significantly reduced, however, by the annealing of specimen at 400 °C, by suppressing the microyielding which is considered to occur related by the grain boundary sliding in restricted regions. The yield stress of the annealed specimens with random textures could be estimated by the Hall-Petch relationship by regarding the length of long-axis of plate-like grains as a grain size between RT and 300 °C. The yield stress of the annealed specimens maintained high values even at 200°C, but it also showed large decreases at 300 °C.

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Indentation-Induced Deformation Behavior in Martensitic Steel Observed through In Situ Nanoindentation in a Transmission Electron Microscopy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.239 ◽

2006 ◽

Vol 503-504 ◽

pp. 239-244 ◽

Cited By ~ 3

Author(s):

Takahito Ohmura ◽

A. Minor ◽

Kaneaki Tsuzaki ◽

J.W. Morris

Keyword(s):

Grain Boundary ◽

Deformation Behavior ◽

Critical Stress ◽

Martensitic Steel ◽

High Angle ◽

Block Boundary ◽

Density Of Dislocations ◽

Transmission Electron ◽

Pile Up

Deformation behavior in the vicinity of grain boundary in Fe-0.4wt%C tempered martensitic steel were studied through in-situ nanoindentation in a TEM. Two types of boundaries were imaged in the dislocated martensitic structure: a low-angle lath boundary and a high-angle block boundary. In the case of a low-angle grain boundary, the dislocations induced by the indenter piled up against the boundary. As the indenter penetrated further, a critical stress appears to have been reached and a high density of dislocations was suddenly emitted on the far side of the grain boundary into the adjacent grain. In the case of the high-angle grain boundary, the numerous dislocations that were produced by the indentation were simply absorbed into the boundary, with no indication of pile-up or the transmission of strain.

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