Molecular Dynamics Study on Uniaxial Compression Transformation of Magnesium Alloy

NANO ◽  
2021 ◽  
pp. 2150118
Author(s):  
Qianhua Yang ◽  
Chun Xue ◽  
Zhibing Chu ◽  
Yugui Li ◽  
Lifeng Ma
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Phase Transformation ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Uniaxial Compression ◽  
Dynamics Simulation ◽  
Basic Knowledge ◽  
Transformation Mechanism ◽  
Different Temperatures

As a new method of calculating materials, molecular dynamics simulation can effectively reproduce the mechanical behavior of materials at the atomic level. In this paper, through the construction of the AZ31 magnesium alloy model, the uniaxial compression deformation of magnesium alloy at different temperatures and strain rate is simulated by molecular dynamics method, the mechanical properties and microstructure changes of magnesium alloy are analyzed, the phase transformation mechanism of magnesium alloy under uniaxial compression is revealed, and the effects of temperature and strain rate on the phase transformation of magnesium alloy are explored at the nanometer scale. It provides a theoretical basis and necessary basic knowledge for the design and development of Mg-based nanostructured alloys with excellent mechanical properties.

scholarly journals Molecular Dynamics Simulation Study of the Mechanical Properties of Nanocrystalline Body-Centered Cubic Iron

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 381-391
Author(s):  
Jan Herman ◽  
Marko Govednik ◽  
Sandeep P. Patil ◽  
Bernd Markert
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Strain Rate ◽  
Tensile Tests ◽  
Dynamics Simulation ◽  
Uniaxial Tensile ◽  
Body Centered Cubic ◽  
Bcc Iron ◽  
Average Grain Size ◽  
Study Results

In the present work, the mechanical properties of nanocrystalline body-centered cubic (BCC) iron with an average grain size of 10 Å were investigated using molecular dynamics (MD) simulations. The structure has one layer of crystal grains, which means such a model could represent a structure with directional crystallization. A series of uniaxial tensile tests with different strain rates and temperatures was performed until the full rupture of the model. Moreover, tensile tests of the models with a void at the center and shear tests were carried out. In the tensile test simulations, peak stress and average values of flow stress increase with strain rate. However, the strain rate does not affect the elasticity modulus. Due to the presence of void, stress concentrations in structure have been observed, which leads to dislocation pile-up and grain boundary slips at lower strains. Furthermore, the model with the void reaches lower values of peak stresses as well as stress overshoot compared to the no void model. The study results provide a better understanding of the mechanical response of nanocrystalline BCC iron under various loadings.

Effects of Vacancy Concentration and Temperature on Mechanical Properties of Single-Crystal γ-TiAl Based on Molecular Dynamics Simulation

2018 ◽  
Vol 37 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Feng Ruicheng ◽  
Cao Hui ◽  
Li Haiyan ◽  
Rui Zhiyuan ◽  
Yan Changfeng
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Elastic Modulus ◽  
Molecular Dynamics Simulation ◽  
Vacancy Concentration ◽  
Dynamics Simulation ◽  
Evolution Process ◽  
Micro Cracks ◽  
Different Temperatures ◽  
External Forces

AbstractMolecular dynamics simulation is used to analyze tensile strength and elastic modulus under different temperatures and vacancy concentrations. The effects of temperature and vacancy concentration on the mechanical properties of γ-TiAl alloy are investigated. The results show that the ultimate stress, ultimate strain and elastic modulus decrease nonlinearly with increasing temperature and vacancy concentration. As the temperature increases, the plastic of material is reinforced. The influence of temperature on strength and elastic modulus is larger than that of vacancy concentration. The evolution process of vacancy could be observed clearly. Furthermore, vacancies with different concentrations develop into voids first as a function of external forces or other factors, micro cracks evolve from those voids, those micro cracks then converge to a macro crack, and fracture will finally occur. The vacancy evolution process cannot be observed clearly owing to the thermal motion of atoms at high temperature. In addition, potential energy is affected by both temperature and vacancy concentration.

scholarly journals Molecular Dynamics Simulation on Mechanical and Piezoelectric Properties of Boron Nitride Honeycomb Structures

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1044 ◽  
Author(s):  
Lu Xie ◽  
Tianhua Wang ◽  
Chenwei He ◽  
Zhihui Sun ◽  
Qing Peng
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Boron Nitride ◽  
Strain Rate ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Piezoelectric Effect ◽  
Failure Strain ◽  
Dynamics Simulation ◽  
Honeycomb Structures

Boron nitride honeycomb structure is a new three-dimensional material similar to carbon honeycomb, which has attracted a great deal of attention due to its special structure and properties. In this paper, the tensile mechanical properties of boron nitride honeycomb structures in the zigzag, armchair and axial directions are studied at room temperature by using molecular dynamics simulations. Effects of temperature and strain rate on mechanical properties are also discussed. According to the observed tensile mechanical properties, the piezoelectric effect in the zigzag direction was analyzed for boron nitride honeycomb structures. The obtained results showed that the failure strains of boron nitride honeycomb structures under tensile loading were up to 0.83, 0.78 and 0.55 in the armchair, zigzag and axial directions, respectively, at room temperature. These findings indicated that boron nitride honeycomb structures have excellent ductility at room temperature. Moreover, temperature had a significant effect on the mechanical and tensile mechanical properties of boron nitride honeycomb structures, which can be improved by lowering the temperature within a certain range. In addition, strain rate affected the maximum tensile strength and failure strain of boron nitride honeycomb structures. Furthermore, due to the unique polarization of boron nitride honeycomb structures, they possessed an excellent piezoelectric effect. The piezoelectric coefficient e obtained from molecular dynamics was 0.702   C / m 2 , which was lower than that of the monolayer boron nitride honeycomb structures, e = 0.79   C / m 2 . Such excellent piezoelectric properties and failure strain detected in boron nitride honeycomb structures suggest a broad prospect for the application of these new materials in novel nanodevices with ultrahigh tensile mechanical properties and ultralight-weight materials.

scholarly journals Molecular dynamics simulation of the effect of solute atoms on the compression of magnesium alloy

2021 ◽  
Vol 127 (6) ◽  
Author(s):  
Qianhua Yang ◽  
Chun Xue ◽  
Zhibing Chu ◽  
Yugui Li ◽  
Lifeng Ma
Keyword(s):  
Molecular Dynamics ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Uniaxial Compression ◽  
Solute Atom ◽  
Dynamics Simulation ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Solute Atoms ◽  
Fcc Structure

AbstractMagnesium alloys have a wide range of application values. To design and develop magnesium alloys with excellent mechanical properties, it is necessary to study the deformation process. In this paper, the uniaxial compression (UC) process of AZ31 magnesium alloy with different solute atom content is simulated by the molecular dynamics method. The effect of the solute atom on the uniaxial compression of magnesium alloy is investigated. It is found that solute atoms can inhibit the grain refinement of magnesium, can effectively improve the plastic strength of the alloy, can change the lattice distortion during uniaxial compression of magnesium alloy, can inhibit the generation of BCC structure, and can slow down the increase of FCC structure and dislocation density. The direction of the FCC structure diffusion is 90° to the grain boundary direction. Shockley partial dislocations are generated around the FCC structure. The direction in which the FCC structure spreads is consistent with the direction in which Shockley partial dislocations move.

scholarly journals Molecular Dynamics Study on Mechanical Properties of Nanopolycrystalline Cu–Sn Alloy

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7782
Author(s):  
Guodong Zhang ◽  
Junsheng Zhao ◽  
Pengfei Wang ◽  
Xiaoyu Li ◽  
Yudong Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Dislocation Density ◽  
Strain Rate ◽  
Dynamics Simulation ◽  
Experimental Characterization ◽  
Tensile Process ◽  
Strength And Ductility

Molecular dynamics simulation is one kinds of important methods to research the nanocrystalline materials which is difficult to be studied through experimental characterization. In order to study the effects of Sn content and strain rate on the mechanical properties of nanopolycrystalline Cu–Sn alloy, the tensile simulation of nanopolycrystalline Cu–Sn alloy was carried out by molecular dynamics in the present study. The results demonstrate that the addition of Sn reduces the ductility of Cu–Sn alloy. However, the elastic modulus and tensile strength of Cu–Sn alloy are improved with increasing the Sn content initially, but they will be reduced when the Sn content exceeds 4% and 8%, respectively. Then, strain rate ranges from 1 × 109 s−1 to 5 × 109 s−1 were applied to the Cu–7Sn alloy, the results show that the strain rate influence elastic modulus of nanopolycrystalline Cu–7Sn alloy weakly, but the tensile strength and ductility enhance obviously with increasing the strain rate. Finally, the microstructure evolution of nanopolycrystalline Cu–Sn alloy during the whole tensile process was studied. It is found that the dislocation density in the Cu–Sn alloy reduces with increasing the Sn content. However, high strain rate leads to stacking faults more easily to generate and high dislocation density in the Cu–7Sn alloy.

scholarly journals Molecular dynamics study on the relationship between phase transition mechanism and loading direction of AZ31

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qianhua Yang ◽  
Chun Xue ◽  
Zhibing Chu ◽  
Yugui Li ◽  
Lifeng Ma ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Magnesium Alloy ◽  
Uniaxial Compression ◽  
Phase Structure ◽  
Stacking Faults ◽  
Az31 Magnesium Alloy ◽  
Face Centered Cubic ◽  
Transformation Mechanism ◽  
Shockley Partial ◽  
Partial Dislocations

AbstractTo develop and design mg-based nanoalloys with excellent properties, it is necessary to explore the forming process. In this paper, to explore the effect of different loading directions on the phase transformation of magnesium alloy, the model of AZ31 magnesium alloy was established, the process of Uniaxial Compression (UC) of magnesium alloy in different directions was simulated, the changes of atomic position and phase structure were observed, and the phase transformation mechanism of AZ31 magnesium alloy under uniaxial compression under different loading directions was summarized. The conclusions are as follows: the stress and strain, potential energy and volume change, void evolution, phase structure change and dislocation evolution of magnesium alloy are consistent, and there is no significant difference. In the process of uniaxial compression, the phase transformation of hexagonal closely packed (HCP) → face-centered cubic (FCC) is the main, and its structure evolves into HCP → Other → FCC. Shockley partial dislocations always precede FCC stacking faults by about 4.5%, and Shockley partial dislocations surround FCC stacking faults. In this paper, the phase transformation mechanism of AZ31 magnesium alloy under uniaxial compression under different loading directions is summarized, which provides a theoretical basis for the processing and development of magnesium-based nanoalloys.

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