TY - JOUR
T1 - Flow strength limit of nanocrystalline tantalum predicted with molecular dynamics simulations
AU - Huang, Cheng
AU - Peng, Xianghe
AU - Zhao, Yinbo
AU - Weng, Shayuan
AU - Yang, Bo
AU - Fu, Tao
N1 - Funding Information:
The authors gratefully acknowledge the financial supports from National Natural Science Foundation of China (Grant Nos. 11332013 , 11802045 ), Chongqing Graduate Student Research Innovation Project (Grant No. CYB17019 ), the Postdoctoral Program for Innovative Talents of Chongqing (Grant No. CQBX201804 ) and China Postdoctoral Science Foundation Funded project (Grant No. 2018M631058 ). MD simulations were carried out at Supercomputing Center of Lv Liang Cloud Computing Center in China.
PY - 2018/12/19
Y1 - 2018/12/19
N2 - The effects of grain size (d) on the flow strength (σflow) as well as the deformation mechanism of nanocrystalline tantalum (NC-Ta) under uniaxial tension were investigated with molecular dynamics (MD) simulations. It showed that there exists a critical grain size of dcr = 7 nm, at which σflow reaches the maximum. Generalized stacking fault energy curves suggest that <111>{110} and <111>{112} are the easiest slip systems for dislocations and twins to occur, and after that the other slip systems might be activated. The twinning mechanism of Ta crystal is analyzed to understand the plastic deformation. For the sample with d > 7 nm, the variation of σflow against d follows the Hall-Petch relationship, attributed to the strengthening due to the accumulations of dislocations and twins with the decrease of d. For the sample with d < 7 nm, the variation of σflow against d exhibits an inverse Hall-Petch relationship, attributed to the softening induced by grain boundary activities. Additionally, cracks can be found in the samples with larger d, but they do not significantly propagate and affect the flow stress. Our simulation results could be beneficial to the design and optimization of such kind of high-performance nano-structured materials.
AB - The effects of grain size (d) on the flow strength (σflow) as well as the deformation mechanism of nanocrystalline tantalum (NC-Ta) under uniaxial tension were investigated with molecular dynamics (MD) simulations. It showed that there exists a critical grain size of dcr = 7 nm, at which σflow reaches the maximum. Generalized stacking fault energy curves suggest that <111>{110} and <111>{112} are the easiest slip systems for dislocations and twins to occur, and after that the other slip systems might be activated. The twinning mechanism of Ta crystal is analyzed to understand the plastic deformation. For the sample with d > 7 nm, the variation of σflow against d follows the Hall-Petch relationship, attributed to the strengthening due to the accumulations of dislocations and twins with the decrease of d. For the sample with d < 7 nm, the variation of σflow against d exhibits an inverse Hall-Petch relationship, attributed to the softening induced by grain boundary activities. Additionally, cracks can be found in the samples with larger d, but they do not significantly propagate and affect the flow stress. Our simulation results could be beneficial to the design and optimization of such kind of high-performance nano-structured materials.
KW - Flow strength
KW - Molecular dynamics
KW - Nanocrystalline Ta
KW - Plasticity
KW - Size effect
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U2 - 10.1016/j.msea.2018.09.053
DO - 10.1016/j.msea.2018.09.053
M3 - Article
AN - SCOPUS:85053838571
VL - 738
SP - 1
EP - 9
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
SN - 0921-5093
ER -