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.

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.

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.

Structure and Elastic Properties of Ni/Cu and Ni/Au Multilayers

1992 ◽  
Vol 291 ◽  
Author(s):  
Ademola Taiwo ◽  
Hong Yan ◽  
Gretchen Kalonji
Keyword(s):  
Phase Transformation ◽  
Elastic Properties ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Multilayer Systems ◽  
Lattice Statics ◽  
Embedded Atom ◽  
Hcp Structure ◽  
Fcc Structure ◽  
Coherent Interfaces

ABSTRACTThe structure and elastic properties of Ni/Cu and Ni/Au multilayer systems are investigated as a function of the number of Ni monolayers built into the systems. We employed lattice statics simulations with the interatomic potentials described by the embedded-atom method. For the Ni/Cu systems, coherent interfaces and FCC structure are maintained, and no elastic anomaly is found. For the Ni/Au systems, when the Ni layers are thick enough, they undergo a strain-induced phase transformation from FCC to HCP structure. An enhancement of Young’s modulus of these systems is found to be associated with this structural change.

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.

scholarly journals Controversy Over Elastic Constants Based on Interatomic Potentials

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
L. G. Zhou ◽  
Hanchen Huang
Keyword(s):  
Elastic Constants ◽  
Necessary Condition ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Embedded Atom

A controversy exists among literature reports of constraints on elastic constants. In particular, it has been reported that embedded atom method (EAM) potentials generally impose three constraints on elastic constants of crystals that are inconsistent with experiments. However, it can be shown that some EAM potentials do not impose such constraints at all. This paper first resolves this controversy by identifying the necessary condition when the constraints exist and demonstrating the condition is physically necessary. Furthermore, this paper reports that these three constraints are eliminated under all conditions, by using response EAM (R-EAM) potentials.

Size dependence and stochastic nature of yield strength of micron-sized crystals: a case study on Ni 3 Al

2006 ◽  
Vol 462 (2070) ◽  
pp. 1661-1681 ◽  
Author(s):  
A.H.W Ngan ◽  
L Zuo ◽  
P.C Wo
Keyword(s):  
Strong Dependence ◽  
Md Simulations ◽  
Al Alloy ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Incipient Plasticity ◽  
Material Volume ◽  
General Material ◽  
Atom Potential

Recent experiments indicate that the first yield point of micron-sized metals exhibits significant statistical scatter as well as strong dependence on the specimen size. In this work, molecular dynamics (MD) simulations are carried out to investigate the onset of shear deformation in a small block of material, using an embedded atom potential for the intermetallic Ni 3 Al alloy. Incipient plasticity in the form of homogeneous dislocation generation is observed to occur at atomic sites with interatomic displacements approaching one-half of the Shockley partial Burgers vector. From the distribution function of the interatomic displacements observed in the MD simulations, the probability of a general material volume surviving under given loading conditions is predicted. The survival probability is then calculated for several situations, including homogeneous deformation and nanoindentation, to predict the critical load for incipient plasticity to occur in these situations. The predicted results are compared to micro-pillar compression and nanoindentation experiments on Ni 3 Al available in the literature.

Embedded-atom-method interatomic potentials from lattice inversion

2010 ◽  
Vol 22 (37) ◽  
pp. 375503 ◽  
Author(s):  
Xiao-Jian Yuan ◽  
Nan-Xian Chen ◽  
Jiang Shen ◽  
Wangyu Hu
Keyword(s):  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Embedded Atom

Monte Carlo Simulation of Phase Separation Behavior in a Cu-Co Alloy Nanoparticle

2002 ◽  
Vol 17 (5) ◽  
pp. 925-928 ◽  
Author(s):  
Jae-Hyeok Shim ◽  
Byeong-Joo Lee ◽  
Jae-Pyoung Ahn ◽  
Young Whan Cho ◽  
Jong-Ku Park
Keyword(s):  
Monte Carlo ◽  
Phase Separation ◽  
Alloy System ◽  
Mixing Enthalpy ◽  
Interatomic Potentials ◽  
Face Centered Cubic ◽  
Embedded Atom ◽  
Mc Simulation ◽  
Phase Separation Behavior ◽  
Separation Behavior

The phase separation behavior in a Cu–Co nanoparticle was investigated using Monte Carlo (MC) simulation. The modified embedded atom method (MEAM) was adopted to describe the interatomic potentials for the Cu–Co alloy system. Some of the cross potential parameters were fitted with experimental data such as mixing enthalpy and lattice constants of Cu–Co alloys. The present MC simulation combined with the MEAM potential describes well the phase separation between face-centered-cubic (fcc) Cu and fcc Co during the annealing of the particle.

Sign in / Sign up

Export Citation Format

Share Document