Molecular Dynamics of Crack Propagation in Nickel and Nickel-Aluminum Bimetal Interface

2010 ◽  
Author(s):  
Yojna Purohit ◽  
Ram Mohan
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Interatomic Potential ◽  
Process Zone ◽  
Crack Tip ◽  
Nickel Aluminum ◽  
Embedded Atom ◽  
Propagation Behavior ◽  
Dynamics Simulations ◽  
Rayleigh Wave Speed

Molecular dynamics simulations were used to study crack propagation in a Nickel single crystal and a Nickel-Aluminum bimetal interface. The embedded atom method interatomic potential was used to investigate the behavior of (001) [100] crack system under mode I loading in the two systems. The propagation mechanisms and fracture behavior and properties of a propagating crack in Ni were compared with propagation, behavior and properties of a surface crack in Ni-Al that initiates and propagates from Ni towards the Ni-Al bimetal interface. Our results for Ni show an initial brittle crack propagation followed by a roughening of the crack surfaces at one-third of the Rayleigh wave speed and are in agreement with previous investigations. In Ni-Al the crack surfaces initially grow brittle. However, two regimes of crack propagation velocities were observed in this case with crack getting decelerated as it nears the interface. Further dynamic analysis of the crack propagation indicated a cease in the crack propagation in Ni due to a brittle to ductile transition. In Ni-Al bimetal interface system, as the crack approaches the interface, a process zone representing local disorder at the crack tip was observed to start growing and interacting with interfacial defects that eventually results in a blunting of the crack tip.

Molecular Dynamics of Crack Growth in Nickel and Nickel-Aluminum Bi-Metallic Interface System Under Cyclic Loading

2011 ◽  
Author(s):  
Yojna Purohit ◽  
Ram Mohan
Keyword(s):  
Molecular Dynamics ◽  
Cyclic Loading ◽  
Crack Propagation ◽  
Crack Growth ◽  
Void Nucleation ◽  
Crack Tip ◽  
Propagation Mechanism ◽  
Crack Plane ◽  
Embedded Atom ◽  
Dynamics Simulations

Molecular dynamics simulations using embedded atom method inter-atomic potential were used to study crack propagation under cyclic loading in a Ni single crystal and a Ni-Al bi-metallic system. The crack in Ni-Al initiates and propagates from Ni towards the Ni-Al interface. The cyclic loading was applied in a strain controlled manner with constant amplitude of maximum strains (emax) applied to the two systems. The crack growth and propagation mechanism of a crack propagating in Ni were compared with the crack growth and propagation of a surface crack in Ni-Al at two different values of emax. Our results suggest that depending on the maximum value of the applied strain (emax), the crack propagates either by fatigue cleavage of the atomic bonds in the crack plane or by void nucleation in the regions near the crack tip. The creation of voids slows down crack growth in both the Ni and Ni-Al at higher value of emax. A comparison of crack growth under tensile and cyclic loading (emax, 0.046) suggest that plastic deformation around crack tip dominate crack propagation during tensile loading that result in slower crack growth (due to early nucleation of dislocations at the crack tip), when compared to crack growth under cyclic loading.

Molecular Dynamics Prediction of the Influence of Composition on Thermotransport in Ni-Al Melts

2017 ◽  
Vol 12 ◽  
pp. 93-110 ◽  
Author(s):  
Tanvir Ahmed ◽  
Elena V. Levchenko ◽  
Alexander V. Evteev ◽  
Zi Kui Liu ◽  
William Yi Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Interatomic Potential ◽  
Diffusion In Solids ◽  
Recent Experimental Study ◽  
Heat Of Transport ◽  
Embedded Atom ◽  
Rich Liquid ◽  
Predicted Values ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential

The influence of composition on thermotransport (coupling between mass and heat transport) in Ni-Al melts is investigated by making use of equilibrium molecular dynamics simulations in conjunction with the Green-Kubo formalism. To describe interatomic interactions in Ni-Al melt models, we employ the embedded-atom method potential developed in [G.P. Purja Pun, Y. Mishin, Phil. Mag., 2009, 89, 3245]. It is demonstrated that the employed interatomic potential gives good agreement with the recent experimental study [E. Sondermann, F. Kargl, A. Meyer, Presented at the 12th International Conference on Diffusion in Solids and Liquids (DSL-2016), 26-30 June 2016, Split, Croatia] regarding the direction of thermotransport in Al-rich liquid Ni-Al alloys. Moreover, the predicted values of the reduced heat of transport (the quantity which explicitly characterizes both the magnitude and direction of thermotransport) in Ni-Al melts, reveal fairly weak composition dependence while being practically independent of temperature at all. Accordingly, in the presence of a temperature gradient, our simulation results for the models of liquid Ni25Al75, Ni50Al50 and Ni75Al25 alloys predict consistently Ni and Al to migrate to the cold and hot ends, respectively. Meanwhile, the highest value, about eV, of the reduced heat of transport is observed for Ni50Al50 alloy model and it slightly decreases towards Al-rich and Ni-rich compositions.

Direct Molecular Dynamics Simulations of Diffusion Mechanisms in NiAl

2000 ◽  
Vol 646 ◽  
Author(s):  
D. Farkas ◽  
B. Soulé de Bas
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Molecular Dynamics Simulations ◽  
Sequential Analysis ◽  
Nearest Neighbor ◽  
Interatomic Potential ◽  
Embedded Atom ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations ◽  
Potential Diffusion

ABSTRACTMolecular dynamics simulations of the diffusion process in ordered B2 NiAl at high temperature were performed using an embedded atom interatomic potential. Diffusion occurs through a variety of cyclic mechanisms that accomplish the motion of the vacancy through nearest neighbor jumps restoring order to the alloy at the end of the cycle. The traditionally postulated 6-jump cycle is only one of the various cycles observed and some of these are quite complex. A detailed sequential analysis of the observed 6-jump cycles was performed and the results are analyzed in terms of the activation energies for individual jumps calculated using molecular statics simulations.

Molecular Dynamics Simulation on Crack Propagation for Magnesium

2009 ◽  
Vol 417-418 ◽  
pp. 21-24
Author(s):  
Shu Sheng Xu ◽  
Xiang Guo Zeng ◽  
Hua Yan Chen
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Crack Tip ◽  
Pure Magnesium ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
External Loading ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Calculation Results

The crack propagation for pure Magnesium at an atomic scale level under external loading was carried out by using a molecular dynamics method. In this study, the Modified Embedded Atom Method (MEAM) was used to characterize the interactions of atoms and the Newtonian equations were solved by Velocity-Verlet algorithm. The crack propagation and failure processes were observed around the crack tip. The calculation results reveal that vacancies were formed near the crack tip during the failure processes for pure Magnesium, and the coalescence between crack tip and vacancies induced the crack growth with the increase in loading.

Molecular Dynamics Study of (001) and (111) Thin Fcc Films

1990 ◽  
Vol 187 ◽  
Author(s):  
F.H. Streitz ◽  
K. Sieradzki ◽  
R. C. Cammarata
Keyword(s):  
Molecular Dynamics ◽  
Interatomic Potential ◽  
Analytic Form ◽  
Jones Potential ◽  
Lennard Jones ◽  
Embedded Atom ◽  
Atomic Interactions ◽  
Low Levels ◽  
Dynamics Simulations ◽  
Thermodynamic Instability

AbstractWe report on the results of molecular dynamics simulations of thin unsupported fcc films ranging in thickness from 20 layers to a monolayer. The films were oriented with either (001) or (111) free surface normals. The atomic interactions were modelled using a standard Lennard-Jones potential and a short range analytic form of the embedded atom potential. The elastic moduli of the films were determined by measuring their response to very low levels of applied stress.We find that the embedded atom and Lennard-Jones results are in relative agreement for (001) films and qualitative disagreement for (111) oriented films. We relate these differences to the nature of the interatomic potential and the thermodynamic instability of the (001) surface.

Molecular Dynamics Simulations of Fracture in Amorphous Silica

1996 ◽  
Vol 455 ◽  
Author(s):  
Jinghan Wang ◽  
Andrey Omeltchenko ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Molecular Dynamics Simulations ◽  
Internal Stress ◽  
Amorphous Silica ◽  
Wave Speed ◽  
Critical Value ◽  
Stress Fields ◽  
Dynamics Simulations ◽  
Rayleigh Wave Speed

ABSTRACTFracture in amorphous silica is studied using million-atom molecular dynamics simulations. The dynamics of crack propagation, internal stress fields, and the morphology of fracture surfaces are examined as a function of temperature and strain rate. At 300K and 600K we observe brittle fracture: internal stress increases to a critical value (typically 2 – 3 GPa) and then turns over when the crack reaches a terminal speed on the order of half the Rayleigh wave speed. At 900K crack propagation slows down dramatically due to plastic deformation and the material becomes ductile.

Molecular Dynamics Study of Size Dependence of Combustion of Aluminum Nanoparticles

2012 ◽  
Vol 1405 ◽  
Author(s):  
Ying Li ◽  
Richard Clark ◽  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Size Dependence ◽  
Interatomic Potential ◽  
Onset Time ◽  
Aluminum Nanoparticles ◽  
Change Rate ◽  
Reactive Molecular Dynamics ◽  
Embedded Atom ◽  
Temperature Change Rate ◽  
Dynamics Simulations

ABSTRACTOxidation dynamics of three different sizes (26, 36 and 46 nm) of single aluminum nanoparticle (ANP) in oxygen environment are studied using multimillion-atom reactive molecular dynamics simulations. In the simulation, each aluminum nanoparticle is coated with an amorphous alumina shell of the same thickness (3 nm), and is ignited by heating the nanoparticle to 1100 K. The metallic aluminum and ceramic alumina are modeled by the Voter- Chen embedded atom model and the interatomic potential by Vashishta et al., respectively. Energy release rate and atomistic-level details of combustion of these single aluminum nanoparticles are investigated, along with the effect of nanoparticle size. The onset temperature of shell Al ejection is found to be independent of the ANP size, whereas the onset time of ejection and the time delay to the highest temperature change rate dT/dt depend on the size.

scholarly journals Development of a New Sr-O Parameterization to Describe the Influence of SrO on Iron-Phosphate Glass Structural Properties Using Molecular Dynamics Simulations

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4326
Author(s):  
Pawel Goj ◽  
Aleksandra Wajda ◽  
Pawel Stoch
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Glass Structure ◽  
Ion Pairs ◽  
Glass Network ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Potential Applications ◽  
Dynamics Simulations

Iron-phosphate glasses, due to their properties, have many potential applications. One of the most promising seems to be nuclear waste immobilization. Radioactive 90Sr isotope is the main short-lived product of fission and, due to its high solubility, it can enter groundwater and pose a threat to the environment. On the other hand, Sr is an important element in hard tissue metabolic processes, and phosphate glasses containing Sr are considered bioactive. This study investigated the effect of SrO addition on a glass structure of nominal 30Fe2O3-70P2O5 chemical composition using classical molecular dynamics simulations. To describe the interaction between Sr-O ion pairs, new interatomic potential parameters of the Buckingham-type were developed and tested for crystalline compounds. The short-range structure of the simulated glasses is presented and is in agreement with previous experimental and theoretical studies. The simulations showed that an increase in SrO content in the glass led to phosphate network depolymerization. Analysis demonstrated that the non-network oxygen did not take part in the phosphate network depolymerization. Furthermore, strontium aggregation in the glass structure was observed to lead to the non-homogeneity of the glass network. It was demonstrated that Sr ions prefer to locate near to Fe(II), which may induce crystallization of strontium phosphates with divalent iron.

Dislocation Generation and Crack Propagation in Metals Examined in Molecular Dynamics Simulations

1992 ◽  
Vol 278 ◽  
Author(s):  
J. A. Rifkin ◽  
C. S. Becquart ◽  
D. Kim ◽  
P. C. Clapp
Keyword(s):  
Crack Propagation ◽  
Atomistic Simulations ◽  
Many Body ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Stress Levels ◽  
Different Temperatures ◽  
The Many ◽  
Dynamics Simulations ◽  
Many Body Interactions

AbstractWe have carried out a series of atomistic simulations on arrays of about 10,000 atoms containing an atomically sharp crack and subjected to increasing stress levels. The ordered stoichiometric alloys B2 NiAl, B2 RuAl and A15 Nb3AI have been studied at different temperatures and stress levels, as well as the elements Al, Ni, Nb and Ru. The many body interactions used in the simulations were derived semi-empirically, using techniques related to the Embedded Atom Method. Trends in dislocation generation rates and crack propagation modes will be discussed and compared to experimental indications where possible, and some of the simulations will be demonstrated in the form of computer movies.

Molecular Dynamics Simulation of Sputtering with Mmany-Body Interactions

1988 ◽  
Vol 100 ◽  
Author(s):  
Davy Y. Lo ◽  
Tom A. Tombrello ◽  
Mark H. Shapiro ◽  
Don E. Harrison
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Single Crystal ◽  
Low Energy ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Many Body ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Small Single Crystal

ABSTRACTMany-body forces obtained by the Embedded-Atom Method (EAM) [41 are incorporated into the description of low energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardments of small, single crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5 keV Ar+ ions have been simulated. The results are compared to simulations using purely pair-wise additive interactions. Significant differences in the spectra of ejected atoms are found.

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