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Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

James W. Evans

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Wenyu Huang

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Patricia A. Thiel

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond 2019 Georgia Southern University

Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond

Timothy A. Bigelow

Friction stir welding is a method of materials processing that enables the joining of similar and dissimilar materials. The process, as originally designed by The Welding Institute (TWI), provides a unique approach to manufacturing—where materials can be joined in many designs and still retain mechanical properties that are similar to, or greater than, other forms of welding. This process is not free of defects that can alter, limit, and occasionally render the resulting weld unusable. Most common amongst these defects are kissing bonds, wormholes and cracks that are often hidden from visual inspection. To identify these defects, various nondestructive ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Chemistry Publications

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond 2019 Georgia Southern University

Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond

Electrical and Computer Engineering Publications

Friction stir welding is a method of materials processing that enables the joining of similar and dissimilar materials. The process, as originally designed by The Welding Institute (TWI), provides a unique approach to manufacturing—where materials can be joined in many designs and still retain mechanical properties that are similar to, or greater than, other forms of welding. This process is not free of defects that can alter, limit, and occasionally render the resulting weld unusable. Most common amongst these defects are kissing bonds, wormholes and cracks that are often hidden from visual inspection. To identify these defects, various nondestructive ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

Chemistry Publications

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

James W. Evans

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

Patricia A. Thiel

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

Theresa Windus

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


The Influence Of Heat Treatment On Corrosion Behavior Of Martensitic Stainless Steel Uns 42670, Armen Kvryan 2019 Boise State University

The Influence Of Heat Treatment On Corrosion Behavior Of Martensitic Stainless Steel Uns 42670, Armen Kvryan

Boise State University Theses and Dissertations

Ceaseless demand for lighter, faster, and more efficient aircraft has been one of the greatest driving forces behind bearing steel innovations. Recent studies demonstrate that corrosion is one of the leading causes of bearing failure in both military and commercial aircraft. High-performing bearing steels are available but are not being used in US military applications due to high cost and security issues when steels are produced outside of the continental United States. One approach to address this issue is to engineer steels that are cost-efficient and heat treated for corrosion resistance, long wear life, etc.

This dissertation presents information on ...


Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong 2019 Iowa State University

Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong

Valery I. Levitas

In this paper, phase transformations (PTs) in silicon were investigated through molecular dynamics (MD) using Tersoff potential. In the first step, simulations of PTs in single crystal silicon under various stress-controlled loading were carried out. Results shows that all instability points under various stress states are described by criteria, which are linear in the space of normal stresses. There is a region in the stress space in which conditions for direct and reverse PTs coincide and a unique homogeneous phase transition (without nucleation) can be realized. Finally, phase transition in bi-crystalline silicon with a dislocation pileup along the grain boundary ...


Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2019 Iowa State University and Ames Laboratory

Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

To assess the energetics of Cu intercalation on defective graphite, the chemical potentials and binding energies for Cu at graphite step edges are calculated for three main configurations: an isolated atom, a chain, and an atom attached to a chain. As expected, for Cu interacting directly with a graphite step edge, the strength of interaction depends on the stability of the step, with Cu binding more strongly at a less-stable step. However, the relationship is reversed when considering binding of a Cu atom attached to a chain. Taken together, these trends mean that if the graphite step is less stable ...


Review Of Fe-6.5 Wt%Si High Silicon Steel—A Promising Soft Magnetic Material For Sub-Khz Application, Gaoyuan Ouyang, Xi Chen, Yongfeng Liang, Chad Macziewski, Jun Cui 2019 Iowa State University and Ames Laboratory

Review Of Fe-6.5 Wt%Si High Silicon Steel—A Promising Soft Magnetic Material For Sub-Khz Application, Gaoyuan Ouyang, Xi Chen, Yongfeng Liang, Chad Macziewski, Jun Cui

Ames Laboratory Accepted Manuscripts

To meet the growing need for energy efficiency in power electronics and electric machines, a number of new soft magnetic materials are being investigated. Among them, high silicon Fe-Si alloy has been recognized as a promising candidate for low-to-medium-frequency applications. Compared to the currently most widely used 3 wt% silicon steel, the steel containing 6.5 wt% Si possesses more favorable properties, including high electrical resistivity, good saturation magnetization, and near-zero magnetostriction. However, the high silicon content facilitates the formation of ordered phases, resulting in severe brittleness that prohibits mass production using the economical conventional processing methods. A number of ...


Effects Of Dopants On The Glass Forming Ability In Al-Based Metallic Alloy, Yang Sun, Feng Zhang, Lin Yang, Huajing Song, Mikhail I. Mendelev, Cai-Zhuang Wang, Kai-Ming Ho 2019 Ames Laboratory

Effects Of Dopants On The Glass Forming Ability In Al-Based Metallic Alloy, Yang Sun, Feng Zhang, Lin Yang, Huajing Song, Mikhail I. Mendelev, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

The effect of dopants on the metallic glass forming ability is usually considered based on the analysis of changes in the liquid structure or thermodynamics. What is missing in such considerations is an analysis of how a dopant changes the properties of the crystal phases which can form instead of the glass. In order to illuminate this aspect we performed molecular dynamics simulations to study the effects of Mg and Sm dopants on the crystal nucleation in Al. The simulation data were found to be consistent with the experimental observations that addition of Mg to Al does not lead to ...


On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins 2019 Iowa State University

On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins

Materials Science and Engineering Publications

Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a ...


Integrated Computational Materials Engineering (Icme) Investigation Of Electrical Conductivity And Thermodynamic Stability For Precipitation Strengthened Al-Zn-Zr And Al-Zn-Ni Ternary Alloys, Oladeji Fadayomi 2019 Michigan Technological University

Integrated Computational Materials Engineering (Icme) Investigation Of Electrical Conductivity And Thermodynamic Stability For Precipitation Strengthened Al-Zn-Zr And Al-Zn-Ni Ternary Alloys, Oladeji Fadayomi

Dissertations, Master's Theses and Master's Reports

High electrical conductivity Al-Zn-TM (TM=Transition metals) alloys with improved mechanical properties and thermal resistance are developed with an integrated computational material engineering (ICME) strategy. From a series of ab initio density functional theory (DFT) simulations assessing combinations of ternary alloys, Al-Zn-Ni and Al-Zn-Zr are determined as alloys with relatively high electrical conductivity compared to several other ternary Al alloy combinations. The zero-temperature stable structure of precipitates formed in these alloys are determined from computed enthalpy of formation as L12, with particular focus of examining the influence of Zn on stabilizing the desired L12 precipitate phase.

Scanning transmission ...


Leaching Characteristics Of Rare Earth Elements From Bituminous Coal-Based Sources, Xinbo Yang 2019 University of Kentucky

Leaching Characteristics Of Rare Earth Elements From Bituminous Coal-Based Sources, Xinbo Yang

Theses and Dissertations--Mining Engineering

The demand for rare earth elements (REEs) has increased over the last decade due to applications in high technology devices including those in the defense industry. The recovery of REEs from primary sources such as rare earth minerals are viable using physical separations followed by chemical processing. However, weak market values and environmental concerns have limited the viability of such operations. On the other hand, REE recovery from secondary sources such as apatite ore, bauxite waste, and waste recycling, provides an opportunity to take advantage of a resource that does not require mining costs as well as other associated costs ...


Performance Of Plunge Depth Control Methods During Friction Stir Welding, Jinyoung Yoon, Cheolhee Kim, Sehun Rhee 2019 Korea Institute of Industrial Technology

Performance Of Plunge Depth Control Methods During Friction Stir Welding, Jinyoung Yoon, Cheolhee Kim, Sehun Rhee

Mechanical and Materials Engineering Faculty Publications and Presentations

Friction stir welding is a preferred solid state welding process for Al/Fe joints, and in friction stir lap welding, the plunge depth is the most critical parameter for joint strength. We compared three plunge depth control methods, namely conventional position control, offset position control, and deflection compensation control in the friction stir lap welding of 3 mm-thick Al 5083-O alloy over 1.2 mm-thick DP 590 steel. The desired plunge depth was 0.2 mm into the steel sheet. However, the pin did not reach the steel surface under conventional position control due to deflection of the vertical axis ...


Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, Boyce Chang, Mario Fratzl, Andrea Boyer, Andrew Martin, Henry C. Ahrenholtz, Isabelle De Moraes, Jean-Francis Bloch, Nora M. Dempsey, Martin M. Thuo 2019 Iowa State University

Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, Boyce Chang, Mario Fratzl, Andrea Boyer, Andrew Martin, Henry C. Ahrenholtz, Isabelle De Moraes, Jean-Francis Bloch, Nora M. Dempsey, Martin M. Thuo

Materials Science and Engineering Publications

Conventional fabrication of microfluidic channels/devices are faced with challenges such as single use channels and/or significant time consumption. We propose a flexible platform for fabricating microfluidic channels simply through indentation on a smart composite—the so-called ST3R (Stiffness tuning through thermodynamic relaxation) composite. The application of ST3R composite allows rapid fabrication of microfluidic channels by hand or with a prefabricated stamp, and precise prototyping of complex designs using a 2D plotter. Indenter geometry, applied stress, filler loading, and number of repeated indentations affect channel dimensions and/or shape. These channels further exhibit; i) Substantial improvement against swelling by ...


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