Stress Induced Martensitic(SIM) Transformations In B2 NiAl Observed in Crack Propagation Computer Simulations

1990 ◽  
Vol 213 ◽  
Author(s):  
Donghyun Kim ◽  
P. C. Clapp ◽  
J. A. Rifkin
Keyword(s):  
Molecular Dynamics ◽  
Martensitic Transformation ◽  
Crack Propagation ◽  
Computer Simulations ◽  
Alloy System ◽  
External Stress ◽  
Embedded Atom Method ◽  
Mode I ◽  
Al Alloy ◽  
Embedded Atom

ABSTRACTIn molecular dynamics studies of 10,000 atom arrays of stoichiometric B2 NiAl containing a crack under external stress in Mode I loading, it has been observed that a martensitic transformation generally occurs (starting in the vicinity of the crack tip) prior to the generation of dislocations and/or the propagation of the crack. The martensitic phase appears to be 2H, in agreement with experimental observations of SIM at higher Ni compositions (62 at % Ni). The interatomic interactions used in the simulations were the Embedded Atom Method (EAM) potentials developed by Voter and Chen [1] for the Ni-Al alloy system.

Molecular Dynamics Study of Crack Propagation in Ni-Al

1988 ◽  
Vol 141 ◽  
Author(s):  
S. Charpenay ◽  
P.C. Clapp ◽  
J.A. Rifkin ◽  
Z.Z. Yu ◽  
A.F. Voter
Keyword(s):  
Crack Propagation ◽  
Crystal Orientation ◽  
Alloy System ◽  
Elastic Response ◽  
Embedded Atom Method ◽  
Al Alloy ◽  
Interatomic Potentials ◽  
Dislocation Generation ◽  
Brittle To Ductile Transition ◽  
Embedded Atom

AbstractUsing an Embedded Atom Method calculation of the interatomic potentials and volume forces in the Ni-Al alloy system, we have examined the plastic and elastic response of an ordered bcc Ni-Al crystal with a pre-existing crack under Mode I loading at various temperatures, stresses and crystal orientation. Depending upon those conditions we found evidence of slip and dislocation generation near the crack tip concomitant with crack propagation. we also saw evidence of a brittle to ductile transition above a certain temperature which is manifested by copious slip and dislocation production. Atomic arrays up to 4000 atoms have been studied.

Some Thermodynamic Properties of NiAl Calculated by Molecular Dynamics Simulations

1988 ◽  
Vol 133 ◽  
Author(s):  
P. C. Clapp ◽  
M. J. Rubins ◽  
S. Charpenay ◽  
J. A. Rifkin ◽  
Z. Z. Yu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Boundary Energy ◽  
Alloy System ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Surface Energies ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Anti Phase Boundary

ABSTRACTCalculations of the surface free energy and anti-phase boundary energy as a function of low index orientations and temperature have been determined for equiatomic perfectly ordered bcc NiAl via molecular dynamics computer simulations. The simulations utilized an Embedded Atom Method calculation of the interatomic potentials and volume forces in the Ni-As alloy system. Values of about 0.95, 1.6, 1.9 and 2.0 J/m2 were found for surface energies of the {100}, {110}, {112} and {111} orientations:, respectively. APB energies of about 0.24 and 0.38 J/m2 were determined for {110} and {112} boundaries, respectively. In addition, we have examined the phase stability and relative energies of the ordered bcc, fcc and bct phases at low temperature, and find a bct phase with c/a = 1.32 slightly lower in energy than the bcc, presaging the martensitic transformation that occurs at finite temperatures in more nickel rich alloys.

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.

Next Generation Safety Analysis Methods for SFRs—(7) Potential Model for Classical Molecular Dynamics on Pu-Fe System

2009 ◽  
Author(s):  
Takahiro Ito ◽  
Tatsumi Arima ◽  
Masashi Himi
Keyword(s):  
Molecular Dynamics ◽  
Potential Model ◽  
Alloy System ◽  
Embedded Atom Method ◽  
First Principle ◽  
Scale Analysis ◽  
Classical Molecular Dynamics ◽  
Embedded Atom ◽  
Modified Embedded Atom Method ◽  
The Individual

Potential model for Modified Embedded Atom Method on Pu-Fe alloy system has been developed to analyze the metal reaction between Pu and Fe with classical molecular dynamics in the framework of the development of the new MPS-based code named ‘COMPASS’ [1] for meso-scale analysis of core disruptive accidents in Sodium-cooled fast reactor. The parameters on Pu-Fe interaction were determined so as to reproduce the properties of PuFe2 intermetallic compound, with applying the potential model for the individual components of Pu and Fe proposed in previous studies. First principle calculations were preformed to compensate for the available experimental data on the material properties of PuFe2. The developed model well reproduces the properties of PuFe2. In the simulation in which the solid Fe is in contact with liquid or solid Pu, formation of crystalline structure of Pu atoms mimicking the Fe structure is observed near the Pu-Fe interface.

Computer Simulations of Cluster-Solid Interactions: Energetic Clusters and Soft Landings

1992 ◽  
Vol 279 ◽  
Author(s):  
Mai Ghaly ◽  
R. S. Averback
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulations ◽  
Three Dimensional ◽  
Embedded Atom Method ◽  
Angle Of Incidence ◽  
Past Work ◽  
Embedded Atom

ABSTRACTThe interaction of small energetic clusters of Cu atoms with Cu surfaces has been investigated by molecular dynamics computer simulations. The simulations are fully dynamical and three dimensional; they employ embedded atom method potentials. The simulations described here are an extension of our past work on cluster solid interactions [1]. In this work, the effects of the angle of incidence, energy, size and temperature of the cluster are examined. In addition, soft landings of Cu clusters on Cu are simulated.

Dislocation Mobilities in NiAl From Molecular Dynamics Simulations

1990 ◽  
Vol 209 ◽  
Author(s):  
A. Moncevicz ◽  
P. C. Clapp ◽  
J. A. Rifkin
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Dislocation Core ◽  
Alloy System ◽  
Shear Velocity ◽  
Peierls Stress ◽  
Al Alloy ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Edge Dislocations

ABSTRACTUsing the Voter-Chen Embedded Atom Method (EAM) potentials for the Ni-Al alloy system,the Peierls stress (σp) and velocity of edge dislocations (b=[100]) have been estimated in stoichiometric perfectly ordered B2 NiAIat a temperature of 10 K, by the use of molecular dynamics simulations employing approximately 4000 atoms. σp was determined to be about 3×1010 dynes/cm2, or about 2%of the shear modulus, C44. The steady state velocity was found to be about 1.6×105 cm/s (or 65% of the (001) shear velocity) under an applied shear stress of 3.9×1010 dynes/cm2. Stress induced martensite (SIM) was nucleated in some of the simulations after the dislocation had begun to move, and in all cases when the SIM reached the immediate neighborhood of the dislocation core the motion of the dislocation was arrested.

Cleavage Planes of Icosahedral Quasicrystals: A Molecular Dynamics Study

2003 ◽  
Vol 805 ◽  
Author(s):  
Frohmut Rösch ◽  
Christoph Rudhart ◽  
Peter Gumbsch ◽  
Hans-Rainer Trebin
Keyword(s):  
Molecular Dynamics ◽  
Brittle Fracture ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Propagation Direction ◽  
Mode I ◽  
Dynamic Crack ◽  
Fracture Surfaces ◽  
Icosahedral Quasicrystals ◽  
Crack Tip Plasticity

ABSTRACTThe propagation of mode I cracks in a three-dimensional icosahedral model quasicrystal has been studied by molecular dynamics techniques. In particular, the dependence on the plane structure and the influence of clusters have been investigated. Crack propagation was simulated in planes perpendicular to five-, two- and pseudo-twofold axes of the binary icosahedral model.Brittle fracture without any crack tip plasticity is observed. The fracture surfaces turn out to be rough on the scale of the clusters. These are not strictly circumvented, but to some extent cut by the dynamic crack. However, compared to the flat seed cracks the clusters are intersected less frequently. Thus the roughness of the crack surfaces can be attributed to the clusters, whereas the constant average heights of the fracture surfaces reflect the plane structure of the quasicrystal. Furthermore a distinct anisotropy with respect to the in-plane propagation direction is found.

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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