scholarly journals Evaluation of void nucleation, growth, and coalescence parameters for HCP-Zr at extreme strain rates

AIP Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 015343
Author(s):  
Wengang Zhou ◽  
Wenjun Chen ◽  
Jiajun Yuan
Keyword(s):  
Void Nucleation ◽  
Strain Rates ◽  
Nucleation Growth

Atomic-scale modeling of the void nucleation, growth, and coalescence in Al at high strain rates

2019 ◽  
Vol 135 ◽  
pp. 98-113 ◽  
Author(s):  
Xin Yang ◽  
Xiangguo Zeng ◽  
Jian Wang ◽  
Jiabin Wang ◽  
Fang Wang ◽  
...  
Keyword(s):  
High Strain ◽  
Void Nucleation ◽  
Atomic Scale ◽  
Strain Rates ◽  
High Strain Rates ◽  
Scale Modeling ◽  
Nucleation Growth

scholarly journals The Modified Void Nucleation and Growth Model (MNAG) for Damage Evolution in BCC Ta

2021 ◽  
Vol 11 (8) ◽  
pp. 3378
Author(s):  
Jie Chen ◽  
Darby J. Luscher ◽  
Saryu J. Fensin
Keyword(s):  
Growth Model ◽  
Damage Evolution ◽  
Volume Fraction ◽  
Void Nucleation ◽  
Nucleation And Growth ◽  
Void Coalescence ◽  
Hydrodynamic Simulations ◽  
Void Evolution ◽  
Void Nucleation And Growth ◽  
Nucleation Growth

A void coalescence term was proposed as an addition to the original void nucleation and growth (NAG) model to accurately describe void evolution under dynamic loading. The new model, termed as modified void nucleation and growth model (MNAG model), incorporated analytic equations to explicitly account for the evolution of the void number density and the void volume fraction (damage) during void nucleation, growth, as well as the coalescence stage. The parameters in the MNAG model were fitted to molecular dynamics (MD) shock data for single-crystal and nanocrystalline Ta, and the corresponding nucleation, growth, and coalescence rates were extracted. The results suggested that void nucleation, growth, and coalescence rates were dependent on the orientation as well as grain size. Compared to other models, such as NAG, Cocks–Ashby, Tepla, and Tonks, which were only able to reproduce early or later stage damage evolution, the MNAG model was able to reproduce all stages associated with nucleation, growth, and coalescence. The MNAG model could provide the basis for hydrodynamic simulations to improve the fidelity of the damage nucleation and evolution in 3-D microstructures.

Characteristics of Hot Ductility and Fracture in Micro-Alloyed Q345B Structural Steel

2011 ◽  
Vol 194-196 ◽  
pp. 150-156 ◽  
Author(s):  
Fang Dong ◽  
Cheng Su ◽  
Yuan Yuan Bai
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Continuous Casting ◽  
Structural Steel ◽  
Void Nucleation ◽  
Hot Ductility ◽  
Strain Rates ◽  
Casting Condition ◽  
Temperature Range ◽  
Scanning Electron

Hot-ductility tests of the microalloyed Q345B structural steel were performed in a tensile machine of Gleeble-1500D at different strain rates of 1.5•10-3/s 、2.5•10-3/s and 2•10-2/s and at temperature range from 1300°C to 700°C(Δ T=100°C ), which are close to the continuous casting condition of steel. Fracture surfaces were examined using a scanning electron microscope; it was found that the hot decrease as strain rate decrease, because the void growth mechanism predominates over void nucleation, giving time for nucleation cracks to grow. The minimum ductility was found at about 800°C for the strain rates of 1.5•10-3/s and 2.5•10-3/s, and the fracture was intergranular. The steel has good plasticity in temperature range from 1200°C to 900°C which is suitable for straighten operation.

scholarly journals Void Nucleation, Growth, and Coalescence Observed by Synchrotron Radiation X-ray Laminography during Tensile Deformation of Fe–0.02 mass% N Alloy

2018 ◽  
Vol 58 (5) ◽  
pp. 943-951 ◽  
Author(s):  
Osamu Furukimi ◽  
Shun Harada ◽  
Yasutaka Mugita ◽  
Masatoshi Aramaki ◽  
Masayuki Yamamoto ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Tensile Deformation ◽  
Void Nucleation ◽  
X Ray ◽  
Nucleation Growth

An Atomistic Perspective on the Effect of Strain Rate and Lithium Fraction on the Mechanical Behavior of Silicon Electrodes

2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Faezeh Darbaniyan ◽  
Xin Yan ◽  
Pradeep Sharma
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Void Nucleation ◽  
Minimum Energy ◽  
Lithium Ion ◽  
State Theory ◽  
Strain Rates ◽  
Surface Sampling

Abstract The process of charging and discharging of lithium-ion batteries results in the periodic intercalation and ejection of lithium ions in the anode material. High-capacity anode materials that are of significant interest for next-generation batteries, such as silicon, undergo large deformation during this process. The ensuing electro-chemo-mechanical stresses and accompanying microstructural changes lead to a complex state of inelastic deformation and damage in the silicon electrode that causes a significant capacity loss within just a few cycles. In this study, we attempt to understand, from an atomistic viewpoint, the mechanisms underlying the plasticity behavior of Si-anode as a function of lithiation. Conventional molecular dynamics simulations are of limited use since they are restricted to loading rates in the order of 108 s−1. Practical charging-discharging rates are several orders of magnitude slower, thus precluding a realistic atomistic assessment of the highly rate-dependent mechanical behavior of lithiated silicon anodes via conventional molecular dynamics. In this work, we use a time-scaling approach that is predicated on the combination of a potential energy surface sampling method, minimum energy pathway, kinetic Monte Carlo, and transition state theory, to achieve applied strain rates as low as 1 s−1. We assess and compare the atomistic mechanisms of plastic deformation in three different lithium concentration structures: LiSi2, LiSi, and Li15Si4 for various strain-rates. We find that the strain rate plays a significant role in the alteration of the deformation and damage mechanisms including the evolution of the plastic deformation, nucleation of shear transformation zone, and void nucleation. Somewhat anomalously, LiSi appears to demonstrate (comparatively) the least strain rate sensitivity.

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