
NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
Recipient: |
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Initial Amendment Date: | March 9, 2010 |
Latest Amendment Date: | March 9, 2010 |
Award Number: | 0954505 |
Award Instrument: | Standard Grant |
Program Manager: |
Tom Kuech
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
Start Date: | March 1, 2010 |
End Date: | February 29, 2016 (Estimated) |
Total Intended Award Amount: | $400,997.00 |
Total Awarded Amount to Date: | $400,997.00 |
Funds Obligated to Date: |
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History of Investigator: |
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Recipient Sponsored Research Office: |
1125 W MAPLE ST STE 316 FAYETTEVILLE AR US 72701-3124 (479)575-3845 |
Sponsor Congressional District: |
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Primary Place of Performance: |
1125 W MAPLE ST STE 316 FAYETTEVILLE AR US 72701-3124 |
Primary Place of
Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): |
MATERIALS AND SURFACE ENG, EPSCoR Co-Funding |
Primary Program Source: |
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Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.041 |
ABSTRACT
The research objective of this Faculty Early Career Development (CAREER) award is to elucidate the fundamental nanoscale and mesoscale mechanisms associated with microstructure development and evolution during vapor deposition, through combined use of atomistic and phase-field simulations. Historically, models for microstructure development during vapor deposition are formulated via extensive experimentation and materials characterization. These phenomenological models do not consider atomic or mesoscale material behavior and thus cannot predict microstructure development in complex heterophase material systems, such as alumina. In this work, atomistic simulations will be used to provide an understanding of the role of ion flux on phase evolution and to compute interface energies between solid metastable phases in alumina. This information will be incorporated into a phase-field model and used to study phase formation and evolution in alumina thin films during simulated physical vapor deposition conditions.
Physical vapor deposition is selected as the application of interest in this CAREER proposal because of its broad relevance across a diverse range of science and engineering disciplines. This proposal strives for a predictive model of microstructure formation during vapor deposition; such a model will allow industry to refine process conditions in a simulation environment rather than through extensive experimentation and materials characterization. This research plan is integrated with education and outreach activities designed to inspire future generations of young men and women to pursue science, technology, engineering and math (STEM). A partnership is proposed with local Boy and Girl Scout organizations to create opportunities for Boy and Girl Scouts to earn merit badges or project award patches in STEM related fields.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The goal of this CAREER award was to develop strategies for modeling the nanoscale and mesoscale mechanisms associated with microstructure development and evolution during physical vapor deposition (PVD), through combined use of atomistic and phase-field simulations. This work focused on complex polymorphic materials where multiple solid phases could form during vapor deposition. Despite industrial use and vast experimentation, no predictive model for microstructure formation and evolution is available for the PVD process. Combined use of atomistic and phase-field simulations is a novel approach to address this important problem.
At the atomic level, this work investigated the structure and energetic stability of different alumina (Al2O3) bulk phases, surfaces and interfaces using molecular statics and molecular dynamics simulations with the ReaxFF interatomic potential. Simulations throughout this work were characterized using a new virtual diffraction algorithm, developed and implemented for this research, that creates both selected area electron diffraction (SAED) and x-ray diffraction (XRD) line profiles without a priori knowledge of the crystal structure of the sample. First, the transferability of the ReaxFF potential was evaluated by modelling different alumina bulk phases. ReaxFF correctly predicted the energetic stability of α-Al2O3 relative to other crystalline alumina phases. Virtual XRD patterns uniquely identified each phase to validate the minimum energy bulk structures through experimental comparison. Next, a wide range of alumina surfaces and interfaces were studied. Predicted minimum energy structures of α-Al2O3 interfaces were in agreement with prior work, which provided the foundation for the first atomistic study of metastable alumina grain boundaries and heterophase alumina interfaces.
At the mesoscale level, this research developed, implemented, and utilized phase-field models to study microstructure evolution in thin films during PVD processing. First, a phase-field model was developed to simulate PVD of a single-phase polycrystalline material by sequentially coupling equations for deposition of single-phase materials and grain evolution in polycrystalline materials. Second, a phase-field model was developed to simulate PVD of a polymorphic material, such as alumina, by sequentially coupling equations for PVD of a single-phase material, evolution in multiphase materials, and phase nucleation. Third, a novel free energy functional was proposed that allowed for simultaneous modeling of PVD and grain evolution in single-phase polycrystalline materials. Finally, these phase-field models were implemented into custom simulation codes and utilized to study PVD thin film growth, grain boundary (GB) evolution, phase evolution and nucleation, and temperature gradients during PVD processing. This work showed that the sequential phase-field model approach, described in tasks (i) and (ii) was sufficient to capture first-order features of the growth process, such as the stagnation of GBs at the valleys of the columnar surface features, but to capture higher-order aspects of growth, such as orientation gradients within columnar grains, the single free energy functional approach developed in task (iii) was necessary.
Physical vapor deposition was selected as the application of interest in this CAREER award because of its broad impact across a diverse range of disciplines in both science and engineering. This proposal developed a predictive model of phase formation and evolution during vapor deposition; such a model may allow numerous industries to refine process conditions in a simulation environment rather than through extensive experimentation. Atomistic simulation and phase-field codes from this work will be available in an open-source envi...
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