Molecular Dynamics Simulation of Nano-Sized Crystallization During Plastic Deformation in an Amorphous Metal

2000 ◽  
Vol 634 ◽  
Author(s):  
R. Tarumi ◽  
A. Ogura ◽  
M. Shimojo ◽  
K. Takashima ◽  
Y. Higo
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Shear Stress ◽  
Phase Transformation ◽  
Molecular Dynamics Simulation ◽  
Shear Strain ◽  
Orientation Relationship ◽  
Crystalline Structure ◽  
Amorphous Metal ◽  
Dynamics Simulation

ABSTRACTAn NTP ensemble molecular dynamics simulation was carried out to investigate the mechanism of nano-sized crystallization during plastic deformation in an amorphous metal. The atomic system used in this study was Ni single component. The total number of Ni atoms was 1372. The Morse type inter-atomic potential was employed. An amorphous model was prepared by a quenching process from the liquid state. Pure shear stresses were applied to the amorphous model at a temperature of 50 K. At applied stresses of less than 2.4GPa, a linear relation between shear stress and shear strain was observed. However, at an applied shear stress of 2.8 GPa, the amorphous model started to deform significantly until shear strain reached to 0.78. During this deformation process, phase transformation from amorphous into crystalline structure (fcc) was observed. Furthermore, an orientation relationship between shear directions and crystalline phase was obtained, that is, two shear directions are parallel to a (111) of the fcc structure. This crystallographic orientation relationship agreed well with our experimental result of Ni-P amorphous alloy. Mechanisms of phase transformation from amorphous into crystalline structure were discussed.

Molecular Dynamics Simulation of Crystallization Process in an Amorphous Metal During Plastic Deformation

2000 ◽  
Vol 2000.2 (0) ◽  
pp. 31-32
Author(s):  
Ryuichi TARUMI ◽  
Akio OGURA ◽  
Masayuki SHIMOJO ◽  
Kazuki TAKASHIMA ◽  
Yakichi HIGO
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Molecular Dynamics Simulation ◽  
Crystallization Process ◽  
Amorphous Metal ◽  
Dynamics Simulation

Molecular dynamics simulation studies on the plastic behaviors of an iron nanowire under torsion

RSC Advances ◽  
2016 ◽  
Vol 6 (34) ◽  
pp. 28792-28800 ◽  
Author(s):  
Chong Qiao ◽  
Yanli Zhou ◽  
Xiaolin Cai ◽  
Weiyang Yu ◽  
Bingjie Du ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Molecular Dynamics Simulation ◽  
Deformation Mechanism ◽  
Driving Force ◽  
Dynamics Simulation ◽  
Simulation Studies ◽  
Plastic Deformation Mechanism ◽  
Constant Torsion ◽  
External Driving

The plastic deformation mechanism of iron (Fe) nanowires under torsion is studied using the molecular dynamics (MD) method by applying an external driving force at a constant torsion speed.

Molecular Dynamics Simulation of the Influence Factors of Particle Depositing on Surface during Cold Spray

2013 ◽  
Vol 652-654 ◽  
pp. 1916-1924 ◽  
Author(s):  
Hong Gao ◽  
Chao Liu ◽  
Fen Hong Song
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Crystalline Structure ◽  
Influence Factors ◽  
Deposition Process ◽  
Dynamics Simulation ◽  
Effective Combination ◽  
Material Hardness ◽  
Higher Temperature ◽  
Soft Cluster

Using molecular dynamics simulation, the influence factors of deposition process, such as cluster incident velocity, material hardness and so on, were studied. The cluster incident velocity influences the combination strength between the substrate and cluster greatly. The higher the cluster velocity is, the stronger the combination strength is, and the faster the cluster forms the crystalline structure like the substrate. Higher temperature of the substrate and the cluster will improve the combination strength. The size of the cluster influences the effect of combination as well. The larger the cluster is, the stronger the combination strength is. If a soft cluster impacts on a hard substrate, because of lack of enough deformation at the interface of the substrate, it is difficult to form the effective combination. If a hard cluster impacts on a soft substrate, the lattice defects occur and the cluster takes a longer time to form crystalline structure.

Experimental study and molecular dynamics simulation of wall slip in a micro-extrusion flowing process

2011 ◽  
Vol 225 (5) ◽  
pp. 1175-1190 ◽  
Author(s):  
D Zhao ◽  
Y Jin ◽  
M Wang ◽  
M Song
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Slip Velocity ◽  
Polymer Melts ◽  
Critical Shear Stress ◽  
Wall Slip ◽  
Dynamics Simulation ◽  
Desorption Mechanism ◽  
Adsorption Desorption

Wall slip is one of the most important characteristics of polymer melts’ elasticity behaviours as well as the most significant factor which affects the flow of polymer melts. Based on the traditional Mooney method, through a double-barrel capillary rheometer, the relationship between velocities of wall slip, shear stress, shear rate, diameters of dies, and temperature of polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethylmethacrylate (PMMA) is explored. The results indicate that the velocities of the wall slip of PP and HDPE increase apparently with shear stress and slightly with temperature. Meanwhile, the rise of temperature results in the decrease of critical shear stress. The wall-slip velocities of PS and PMMA are negative which means that the Mooney method based on the adsorption–desorption mechanism has determinate limitation to calculate the wall-slip velocity. Based on the entanglement–disentanglement mechanism, a new wall-slip model is built. With the new model, the calculation values of velocity of PP and HDPE correspond to the experimental values very well and the velocities of PS and PMMA are positive. The velocities of PS and PMMA increase obviously with the rise of shear stress. The rise of temperature results in the increase of velocity and decrease of critical shear stress. Then, the molecular dynamics simulation is used to investigate the combining energy between four polymer melts and the inside wall. The results show that at the given temperature and pressure, the molecules of PS and PMMA combine with atoms of the wall more tightly than those of PP and HDPE which means when wall slip occurs, the molecules of PS and PMMA near the wall will adsorb to the surface of the wall. However, those of PP and HDPE will be easy to slip. Therefore, the wall-slip mechanism of PP and HDPE is the adsorption–desorption mechanism, and that of PS and PMMA is the entanglement–disentanglement mechanism. According to the different wall-slip mechanisms of four polymers, an all-sided calculation method of wall-slip velocity is raised which consummates the theory of wall slip of polymer melts.

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