Doctoral Dissertations

Avik Mahata

Keywords and Phrases

Aluminum alloys; LAMMPS; MEAM Potential; Molecular Dynamics; Nucleation; Solidification

Abstract

"Homogeneous nucleation during solidification in Al (fcc), Fe (bcc) and Mg (hcp) is studied by million-atom molecular dynamics (MD) utilizing the second nearest neighbor modified embedded atom method (2NN-MEAM) potentials. Spontaneous homogenous nucleation from the melt was produced without any influence of pressure, free surface effects and impurities. We also study the effect on the simulation size on homogenous nucleation and the heterogeneity in homogenous nucleation. The heterogeneity in homogenous nucleation originates from the twins, grain boundaries and short range order in the liquid during the initial stages of solidification.

To study the solid-liquid coexistence in binary Al alloys, interatomic potentials for binary Al-Cu, Al-Fe, Al-Ni, Al-Mg, Al-Si and Al-Ge alloys were developed based on 2NN-MEAM formalism. Using these interatomic potentials, we compare formation energies, elastic constants, lattice parameters, enthalpy of solid and liquid mixing with experimental or first principle data of the binary Al alloys. In addition, we also compare the liquidus temperature of the Al-alloys from the phase diagram to the MD simulation.

Finally, directional solidification of Al-11 at. % Cu is shown utilizing the 2NN-MEAM interatomic potential. The condition for directional solidification is produced by imposing dissimilar temperatures at the model boundaries along the [100] solidification direction to create a temperature gradient. Both the microstructural properties of solidified alloys and the mechanical properties under uniaxial tension is investigated”--Abstract, page iv.

Advisor(s)

Asle Zaeem, Mohsen

Committee Member(s)

O'Malley, Ronald J.
Kumar, Aditya
Zhou, Caizhi
Chernatynskiy, Aleksandr V.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Comments

The author acknowledges the funding support from the National Science Foundation under Grant No. NSF-CMMI 1537170.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2019

Journal article titles appearing in thesis/dissertation

  • Understanding Homogeneous Nucleation in Solidification of Aluminum by Molecular Dynamics Simulations
  • Evolution of Solidification Defects in Deformation of Nano-Polycrystalline Aluminum
  • Size Effect on Nucleation Process during Solidification of Pure Metals by Atomistic Simulations
  • Evidence of Liquid Ordering and Heterogeneities in Homogeneous Nucleation during Solidification of Pure Metals
  • Solid-Liquid Coexistence of Binary Al alloys by Molecular Dynamics Simulation Using Modified Embedded Method
  • Effects of Solidification Defects on Nanoscale Mechanical Properties of Rapid Directionally Solidified Al-Cu Alloy

Pagination

xviii, 231 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2019 Avik Kumar Mahata, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12037

Electronic OCLC #

1313117356

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