Generalized Melting Criterion for Amorphization

MRS Proceedings ◽

10.1557/proc-291-653 ◽

1992 ◽

Vol 291 ◽

Cited By ~ 1

Author(s):

R. Devanathan ◽

N. Q. Lam ◽

P. R. Okamoto ◽

M. Meshii

Keyword(s):

Solid State ◽

Strong Support ◽

Atomic Displacement ◽

Mean Square ◽

Root Mean Square Amplitude ◽

Embedded Atom ◽

Average Shear ◽

Lindemann Criterion ◽

Dynamics Simulations ◽

State Amorphization

ABSTRACTWe present a thermodynamic model of solid-state amorphization based on a generalization of the well-known Lindemann criterion. The original Lindemann criterion proposes that melting occurs when the root-mean-square amplitude of thermal displacement exceeds a critical value. This criterion can be generalized to include solid-state amorphization by taking into account the static displacements. In an effort to verify the generalized melting criterion, we have performed molecular dynamics simulations of radiation-induced amorphization in NiZr, NiZr2, NiTi and FeTi using embedded-atom potentials. The average shear elastic constant G was calculated as a function of the total mean-square atomic displacement following random atom-exchanges and introduction of Frenkel pairs. Our results provide strong support for the generalized melting criterion.

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Calculation of Glass-Forming Ability in the Ni-Zr and Ni-Ti Systems from Interatomic Potentials

MRS Proceedings ◽

10.1557/proc-644-l4.2 ◽

2000 ◽

Vol 644 ◽

Author(s):

W.S. Lai ◽

B.X. Liu

Keyword(s):

Solid State ◽

Solid Solutions ◽

Amorphous State ◽

Md Simulations ◽

Interatomic Potentials ◽

Glass Forming ◽

Lindemann Criterion ◽

Amorphous States ◽

State Amorphization ◽

Amorphous Interlayer

AbstractFor the Ni-Zr and Ni-Ti systems, Molecular-dynamics (MD) simulations are conducted to compare the relative stability of the terminal solid solutions versus the corresponding amorphous states as a function of solute concentrations. It turns out that the terminal solid solutions transform into an amorphous state spontaneously when the solute concentrations are beyond the maximum allowable values, i.e. the critical solubilities, determined to be 14 at.% Zr in Ni and 25 at.% Ni in Zr for Ni-Zr system and 38 at.% Ti in Ni and 15 at.% Ni in Ti for the Ni-Ti system, respectively. The glass-forming ranges are therefore deduced to be within the respective critical solubilities, i.e. 14-75 at.% Zr and 38-85 at.% Ti for the Ni-Zr and Ni-Ti systems, respectively, which are compatible with those from experiments and/or from the generalized Lindemann criterion. Moreover, MD simulation also reveals that solid-state amorphization does take place and that the growth of the amorphous interlayer follows exactly a t½ law. Besides, a solubility criterion is proposed that the lower the maximum solid solubility the less stable is the lattice of the metal upon solid-state reaction and it can explain the fact that the growing speed of amorphous interlayer toward Ni (melting point = 1528 K) is greater than that directed to the Zr (2128 K) lattice, while it is smaller than that to Ti (1941 K) side.

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Molecular Dynamics Simulation of Radiation-Induced Amorphization of the Ordered Compound NiZr2

MRS Proceedings ◽

10.1557/proc-279-511 ◽

1992 ◽

Vol 279 ◽

Author(s):

R. Devanathan ◽

N. Q. Lami ◽

P. R. Okamoto ◽

M. Meshii

Keyword(s):

Molecular Dynamics ◽

Perfect Crystal ◽

Dynamics Simulation ◽

Embedded Atom ◽

Chemical Disorder ◽

Average Shear ◽

Ordered Intermetallic ◽

Radiation Induced ◽

Diffraction Patterns ◽

Dynamics Simulations

ABSTRACTWe have studied the electron irradiation-induced amorphization of the ordered intermetallic compound NizR2 by molecular dynamics simulations in conjunction with embedded-atom potentials. Randomly chosen Frenkel pairs and chemical disorder were introduced into the system in separate processes. In both cases, the energy and volume of the system rose above the corresponding levels of a quenched liquid and the calculated diffraction patterns indicated the occurence of a crystalline-to-amorphous transition. In addition, the average shear elastic constant fell to about 50% of its value in the perfect crystal and the system became elastically isotropie. These results indicate that NiZr2 can be amorphized by chemical disorder as well as Frenkel pairs and are in good agreement with experimental observations.

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Thermodynamic parallels between solid-state amorphization and melting

Journal of Materials Research ◽

10.1557/jmr.1990.0286 ◽

1990 ◽

Vol 5 (2) ◽

pp. 286-301 ◽

Cited By ~ 168

Author(s):

D. Wolf ◽

P. R. Okamoto ◽

S. Yip ◽

J. F. Lutsko ◽

M. Kluge

Keyword(s):

Solid State ◽

Amorphous Phase ◽

Mechanical Instability ◽

Extended Phase ◽

Thermally Activated ◽

Underlying Causes ◽

Characteristic Features ◽

Dynamics Simulations ◽

Solid Liquid ◽

State Amorphization

A thermodynamics-based description, in the form of an extended phase diagram, of melting and solid-state amorphization is proposed which brings out the parallels between these two phenomena and suggests that their underlying causes are apparently the same. Through molecular dynamics simulations we demonstrate that every crystal, in principle, can undergo two different types of melting transitions with characteristic features that are also observed in radiation- and hydrogenation-induced amorphization experiments on ordered alloys. The first type, defined in terms of free energies, is shown to involve the heterogeneous nucleation of the liquid or amorphous phase at extended lattice defects (such as grain boundaries, free surfaces, voids, or dislocations) and subsequent thermally-activated propagation of solid-liquid/amorphous interfaces through the crystal. The second type, arising from a mechanical instability limit described by Born, is homogeneous and does not require thermally-activated atom mobility. It is suggested that the role of chemical and structural disordering, a prerequisite for irradiation- but not hydrogenation-induced solid-state amorphization, is merely to drive the crystal lattice to a critical combination of volume and temperature at which the amorphous phase can form either heterogeneously or homogeneously.

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Solid-State Amorphization Observed in the Equilibrium-Immiscible Cu−Re System by Molecular Dynamics Simulations

The Journal of Physical Chemistry B ◽

10.1021/jp052509s ◽

2005 ◽

Vol 109 (34) ◽

pp. 16463-16468 ◽

Cited By ~ 6

Author(s):

J. H. Li ◽

S. H. Liang ◽

B. X. Liu

Keyword(s):

Molecular Dynamics ◽

Solid State ◽

Molecular Dynamics Simulations ◽

Dynamics Simulations ◽

State Amorphization

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Faculty Opinions recommendation of Light activation of rhodopsin: insights from molecular dynamics simulations guided by solid-state NMR distance restraints.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.2426988.2061090 ◽

2010 ◽

Author(s):

James Bowie

Keyword(s):

Molecular Dynamics ◽

Solid State ◽

Molecular Dynamics Simulations ◽

Solid State Nmr ◽

Light Activation ◽

Distance Restraints ◽

Dynamics Simulations

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Solid state amorphization of organic molecular crystals using a vibrating mill

Solid State Communications ◽

10.1016/0038-1098(95)00161-1 ◽

1995 ◽

Vol 94 (12) ◽

pp. 1013-1018 ◽

Cited By ~ 34

Author(s):

Itaru Tsukushi ◽

Osamu Yamamuro ◽

Takasuke Matsuo

Keyword(s):

Solid State ◽

Molecular Crystals ◽

Organic Molecular Crystals ◽

State Amorphization

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Phase sequence in the solid state amorphization reaction of metallic thin films

Thin Solid Films ◽

10.1016/0040-6090(89)90863-8 ◽

1989 ◽

Vol 174 ◽

pp. 11-24 ◽

Cited By ~ 5

Author(s):

S. Schneider ◽

H. Schröder ◽

K. Samwer ◽

B. Schuhmacher ◽

U. Köster

Keyword(s):

Thin Films ◽

Solid State ◽

Metallic Thin Films ◽

Phase Sequence ◽

State Amorphization

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Thermal Conductivity of Cage-Like Structures

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44276 ◽

2011 ◽

Author(s):

Mona Zebarjadi ◽

Keivan Esfarjani ◽

Gang Chen

Keyword(s):

Thermal Conductivity ◽

Atomic Displacement ◽

Rectangular Lattice ◽

Local Minima ◽

Atomic Displacement Parameter ◽

Band Dispersion ◽

Dynamics Simulations ◽

Filler Mass ◽

The Right ◽

Double Well Potential

A two dimensional toy model is developed to study thermal transport in cage like structures such a skutterudites and clathrates. The model consists of host atoms on a rectangular lattice with fillers in the center of each rectangle. The thermal conductivity is calculated by using Green-Kubo equilibrium molecular dynamics simulations. It is generally believed that the smaller and the heavier the filler, the lower is the thermal conductivity. We show that the thermal conductivity decreases with atomic displacement parameter while it has local minima versus filler mass. Our study shows that it is very important to include the correct band dispersion to get the right features of the thermal conductivity. We show that by having a double well potential one can further reduce the thermal conductivity.

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