Electronic Theses and Dissertations

Date

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Committee Chair

Ebrahim Asadi

Committee Member

Amir Hadadzadeh

Committee Member

Mohamed Laradji

Committee Member

Gladius Lewis

Abstract

Design of novel materials and novel manufacturing process requires understandingthermophysical properties of materials during their process and working conditions.Microstructure of materials, which is usually, consists of grains, phases, and defectsdetermines the overall physical and mechanical properties of materials. Specifically inmetals, the formation of solid crystal from liquid is considered as one of the most importantfactors during the solidification, which can elucidate the final formation of microstructureof materials. The experimental study of the phenomena related to the coexistence of solidliquid phases is generally arduous, because the experiments are needed to be carried out atthe melting points of the materials. Thanks to recent improvements in computational powerand supercomputing capabilities, many research and industrial institutions have started toemploy computational materials modeling as a suitable alternative to costly and/orimpractical experiments. Molecular dynamic (MD) is a powerful computational approachthat can be used for tracking individual atoms with great accuracy in length scales of tensto hundreds nanometers and timescales of picoseconds to nanoseconds. However, thereliability of MD simulations for each alloy system is based on the reliability of how theatoms talk or interact with each other, through the interatomic potential energy.Interatomic potentials, which are mathematical functions of the coordinates of all atoms inthe system, are essential for determining both equilibrium and non-equilibrium propertiesof materials. The objective of this work is to develop advanced interatomic potentials inthe concept of modified embedded-atom method (MEAM) for alloy system that are capableof predictive modeling of alloys in solid-liquid transitions. Interatomic potentials includingMEAM contain parameters that are determined by fitting model predictions to specificexperimental or first principle data, which are mostly to the 0-K properties. In order tostudy the liquid and solid properties at high and the near melting point, the potential has tobe fitted to the not only 0-K properties but also to the high temperature properties such asmelting point and elastic constants at high temperatures. Therefore, our goal in this thesis,is calculating the thermodynamics and kinetics properties of solid and liquid in metallicsystem at high temperatures by MD simulation through developing reliable interatomicpotential for studying pure Fe, Cu, Ni, Ti, Pb, and Sn and binary system (Pb-Sn).

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

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