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Substitutional And Interstitial Doping In Laco5 System For The Development Of Hard Magnetic Properties: A First Principles Study, Huseyin Ucar, Renu Choudhary, Durga Paudyal 2020 California State Polytechnic University - Pomona

Substitutional And Interstitial Doping In Laco5 System For The Development Of Hard Magnetic Properties: A First Principles Study, Huseyin Ucar, Renu Choudhary, Durga Paudyal

Ames Laboratory Accepted Manuscripts

We investigate here the changes in the electronic structure at the transition metal sites of the RE-TM5 structure (RE = Rare Earth, TM = Transition Metal) while doping the interstitial sites with nitrogen. LaCo5 compound is taken as the baseline compound owing to its critically needed intrinsic magnetic properties such as magneto-crystalline anisotropy energy (MAE) of ≈5 meV/fu [1] due to the contributions from the cobalt network. In addition, because of the lack of 4f electrons in lanthanum, complications originating from the treatment of the 4f localized electrons are absent in this compound; making it an ideal reference material to all ...


Non-Equilibrium Growth Of Metal Clusters On A Layered Material: Cu On Mos2, Dapeng Jing, Ann Lii-Rosales, King C. Lai, Qiang Li, Jaeyoun Kim, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2020 Iowa State University and Ames Laboratory

Non-Equilibrium Growth Of Metal Clusters On A Layered Material: Cu On Mos2, Dapeng Jing, Ann Lii-Rosales, King C. Lai, Qiang Li, Jaeyoun Kim, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

We use a variety of experimental techniques to characterize Cu clusters on bulk MoS2 formed via physical vapor deposition of Cu in ultrahigh vacuum, at temperatures ranging from 300 K to 900 K. We find that large facetted clusters grow at elevated temperatures, using high Cu exposures. The cluster size distribution is bimodal, and under some conditions, large clusters are surrounded by a denuded zone. We propose that defect-mediated nucleation, and coarsening during deposition, are both operative in this system. At 780 K, a surprising type of facetted cluster emerges, and at 900 K this type predominates: pyramidal clusters with ...


Defect Characterization Of Additively Manufactured Parts, Sabrina D'Alesandro, Joy Gockel, Andrew Harvey 2020 Wright State

Defect Characterization Of Additively Manufactured Parts, Sabrina D'Alesandro, Joy Gockel, Andrew Harvey

Symposium of Student Research, Scholarship, and Creative Activities Materials

This document describes various image processing techniques to be used for defect characterization of additively manufactured parts. This will help the reader gain knowledge of materials science engineering and the nuances in analyzing data from image processing software.

Additive manufacturing is shaping the manufacturing world through simplistic household printers’ to more complex metal printers used for a variety of applications. Specifically, laser powder bed fusion (LPBF) is an additive manufacturing process that deposits metal powder over the build plate and melts it with a laser in the shape of the build part. In order to make LPBF more efficient with ...


A Novel Method For Making Titanium Dioxide For Photocatalytic Applications, Gary Wilson 2020 Montana Tech

A Novel Method For Making Titanium Dioxide For Photocatalytic Applications, Gary Wilson

Graduate Theses & Non-Theses

Titanium dioxide possesses near-ideal properties for large-scale application as a photocatalyst. It is cheap and abundant, nontoxic, and environmentally safe. However, it still suffers from logistical problems preventing its application in industry: namely, rapid electron-hole recombination and inability to utilize visible light. For nearly five decades researchers in this booming field have made numerous attempts to address these problems, doping and combining titanium dioxide with a wide range of materials. A novel ambient-temperature approach to synthesis and doping/modification of anatase-form titanium dioxide was attempted using both oxygen-rich and oxygen deprived synthetic routes. Reactants were exposed to various wavelengths of ...


Effect Of Frother Strength And Solids On Gas Dispersion In A Cavitation Sparger Measured By Electrical Resistance Tomography, Philip Holdsworth 2020 Montana Tech

Effect Of Frother Strength And Solids On Gas Dispersion In A Cavitation Sparger Measured By Electrical Resistance Tomography, Philip Holdsworth

Graduate Theses & Non-Theses

Gas dispersion in column flotation is critical for optimizing particle-bubble interaction and maximizing recovery. The effect of various flotation frothers on axial gas dispersion rates in a column flotation cell were measured using electrical resistance tomography (ERT). Tests included two-phase (gas-liquid) and three-phase (gas-liquid-solid) to determine the effect of mechanical parameters and the presence of solids on gas dispersion. Gas holdup can be measured using ERT and utilized in the determination of axial gas dispersion rate in the column. The ERT is constructed with two sensor planes making it possible to simultaneously capture gas holdup values at one cm and ...


Formation Of Size And Density Controlled Nanostructures By Galvanic Displacement, Minh Tran, Sougata Roy, Steven Kmiec, Alison Whale, Steve W. Martin, Sriram Sundararajan, Sonal Padalkar 2020 Iowa State University

Formation Of Size And Density Controlled Nanostructures By Galvanic Displacement, Minh Tran, Sougata Roy, Steven Kmiec, Alison Whale, Steve W. Martin, Sriram Sundararajan, Sonal Padalkar

Mechanical Engineering Publications

Gold (Au) and copper (Cu)-based nanostructures are of great interest due to their applicability in various areas including catalysis, sensing and optoelectronics. Nanostructures synthesized by the galvanic displacement method often lead to non-uniform density and poor size distribution. Here, density and size-controlled synthesis of Au and Cu-based nanostructures was made possible by galvanic displacement with limited exposure to hydrofluoric (HF) acid and the use of surfactants like L-cysteine (L-Cys) and cetyltrimethylammonium bromide (CTAB). An approach involving cyclic exposure to HF acid regulated the nanostructure density. Further, the use of surfactants generated monodisperse nanoparticles in the initial stages of the ...


Subsurface Cooling Rates And Microstructural Response During Laser Based Metal Additive Manufacturing, Vivek Thampy, Anthony Y. Fong, Nicholas P. Calta, Jenny Wang, Aiden A. Martin, Philip J. Depond, Andrew M. Kiss, Gabe Guss, Qingfeng Xing, Ryan T. Ott, Anthony van Buuren, Michael F. Toney, Johanna Nelson Weker, Matthew J. Kramer, Manyalibo J. Matthews, Christopher J. Tassone, Kevin H. Stone 2020 SLAC National Accelerator Laboratory

Subsurface Cooling Rates And Microstructural Response During Laser Based Metal Additive Manufacturing, Vivek Thampy, Anthony Y. Fong, Nicholas P. Calta, Jenny Wang, Aiden A. Martin, Philip J. Depond, Andrew M. Kiss, Gabe Guss, Qingfeng Xing, Ryan T. Ott, Anthony Van Buuren, Michael F. Toney, Johanna Nelson Weker, Matthew J. Kramer, Manyalibo J. Matthews, Christopher J. Tassone, Kevin H. Stone

Ames Laboratory Accepted Manuscripts

Laser powder bed fusion (LPBF) is a method of additive manufacturing characterized by the rapid scanning of a high powered laser over a thin bed of metallic powder to create a single layer, which may then be built upon to form larger structures. Much of the melting, resolidification, and subsequent cooling take place at much higher rates and with much higher thermal gradients than in traditional metallurgical processes, with much of this occurring below the surface. We have used in situ high speed X-ray diffraction to extract subsurface cooling rates following resolidification from the melt and above the β-transus ...


Half-Metallic Compositional Ranges For Selected Heusler Alloys, Nikolai A. Zarkevich, Prashant Singh, Andrei V. Smirnov, Duane D. Johnson 2020 Ames Laboratory

Half-Metallic Compositional Ranges For Selected Heusler Alloys, Nikolai A. Zarkevich, Prashant Singh, Andrei V. Smirnov, Duane D. Johnson

Materials Science and Engineering Publications

For a material that is a half-metal, there should exist a range of compositions for half-metallicity. This compositional range can be expressed in terms of electron count and computed. We investigate electronic and magnetic properties of doped full- and half-Heusler alloys (stoichiometry XYZ2 and XYZ, respectively) with elements X from groups 13-16 and periods 3-6 of the Periodic Table, Y={Mn, Fe}, and Z={Co, Ni}. Using spin density functional theory, we predict shifts of the Fermi energy in the doped and solid-solution alloys. These predictions can be used for band-gap engineering of multicomponent half-metals and provide the viable range ...


Table Top Dome Tester, Travis Bernard, Sarah Kassinger, Amanda O'Reilly, Scott Salerno 2020 The University of Akron

Table Top Dome Tester, Travis Bernard, Sarah Kassinger, Amanda O'Reilly, Scott Salerno

Williams Honors College, Honors Research Projects

The Erichsen Cupping Test was used as a basis to design a dome tester. The intention of a dome tester is to test sheet metal material properties in all directions. This was done by clamping a piece of sheet metal and using a piston and hydraulic press to punch through the material. The force used to punch the material and the height of the deforming material can be gathered and the sheet metal properties can then be calculated. At the end of the project the team was able to successfully design and manufacture a hydraulic dome tester. However, due to ...


Tabletop Mechanical Tester, Jamie Dombroski, Andrew Shirk, Richard Leffler, Brian English 2020 The University of Akron

Tabletop Mechanical Tester, Jamie Dombroski, Andrew Shirk, Richard Leffler, Brian English

Williams Honors College, Honors Research Projects

The need for hands-on and face-to-face experiences in the engineering classroom is very great. The equations, principles, and concepts can all be learned, but without the visual and tactile application, these don’t always sink in or become concrete. A small-scale tensile test machine was designed, sourced, manufactured, and tested for the purpose of being applied in classroom settings to provide this experience to engineering students. Extensive research was performed concerning tensile machines on the market, the essential elements of which are the load cell, grips, crosshead, extensometer, motor, and frame. The raw materials for the frame were purchased and ...


Tabletop Mechanical Tester, Jamie Dombroski, Brian English, Richard Leffler, Andrew Shirk 2020 The University of Akron

Tabletop Mechanical Tester, Jamie Dombroski, Brian English, Richard Leffler, Andrew Shirk

Williams Honors College, Honors Research Projects

The need for hands-on and face-to-face experiences in the engineering classroom is very great. The equations, principles, and concepts can all be learned, but without the visual and tactile application, these don’t always sink in or become concrete. A small-scale tensile test machine was designed, sourced, manufactured, and tested for the purpose of being applied in classroom settings to provide this experience to engineering students. Extensive research was performed concerning tensile machines on the market, the essential elements of which are the load cell, grips, crosshead, extensometer, motor, and frame. The raw materials for the frame were purchased and ...


The Corrosion Behavior Of Aisi 304l Stainless Steel In Simulated Concrete Pore Solution. And A New Marketing Plan For Stainless Steel Rebars., Kenny Aronson 2020 The University of Akron

The Corrosion Behavior Of Aisi 304l Stainless Steel In Simulated Concrete Pore Solution. And A New Marketing Plan For Stainless Steel Rebars., Kenny Aronson

Williams Honors College, Honors Research Projects

The purpose of this project is to study the corrosion behavior of AISI 304L stainless steel, and to present the results for a new marketing strategy for a steel rebar manufacturer. This experiment involved the usage of cyclic potentiodynamic polarization tests to investigate the effect of chlorides on the pitting corrosion behavior of AISI 304L stainless steel in a simulated concrete pore solution with 3.5 wt.% chlorides. The results of this experiment showed that the chlorides caused a large increase in the corrosion current density of AISI 304L stainless steel indicating increased susceptibility to general corrosion and pitting corrosion ...


Galvanic Corrosion In Aluminum/Steel Joints, Maegan Saul 2020 The University of Akron

Galvanic Corrosion In Aluminum/Steel Joints, Maegan Saul

Williams Honors College, Honors Research Projects

As car manufacturers seek to use lighter weight materials, aluminum is being more commonly used in the construction of vehicles. However, the strength of steel cannot be matched and both metals are necessary, leading to the joining of dissimilar metals. This connection of different metals leads to a galvanic coupling and subsequent corrosion of the less noble metal. This project aims to observe the corrosion and galvanic coupling behavior of aluminum alloys and carbon steel so that a model may be produced which can accurately predict the expected responses of the metals in various environments. Better, more accurate modeling of ...


Jominy Hardenability Tester With In-Situ Heating, Luke Allen 2020 The University of Akron

Jominy Hardenability Tester With In-Situ Heating, Luke Allen

Williams Honors College, Honors Research Projects

This project centers on building a Jominy Hardenability tester with In-Situ heating for the manufacturing lab at the University of Akron. A new process and setup will be designed using engineering concepts in order to make the testing more efficient and safer for the teaching and testing of metal hardness. The current Jominy testing setup has efficiency issues within the transfer of specimen from induction heater to testing rig. Our design will simplify the design by creating a test rig that removes the traveling aspect of the specimen which will limit the amount of premature cooling done and will be ...


Additive Manufacturing Of Copper-Based Alloy By Laser Powder Bed Fusion, Binghao Lu 2020 University of Central Florida

Additive Manufacturing Of Copper-Based Alloy By Laser Powder Bed Fusion, Binghao Lu

Electronic Theses and Dissertations, 2020-

Copper (Cu) and Cu-alloy are good candidates for the engineered components that require good thermal and electrical conductivity. Since industry often needs sophisticated components that cannot be made easily by traditional methods, such as casting, forging and machining, research for additive manufacturing of copper-based alloy is on demand. Therefore, this thesis focuses on the optimization of laser powder bed fusion (LPBF) of Cu-10 wt.% Sn alloy and pure Cu based on their characteristics such as relative density/porosity, surface roughness, phase constitutes, melt pool dimension, and dendrite arm spacings dimension, determined by optical microscopy, X-ray diffraction and Scanning electron microscope ...


Effect Of Annealing On The Contact Resistance Of Aluminum On A P-Type Substrate, Shrey Shah, George Patrick Watson 2019 Singh Center for Nanotechnology

Effect Of Annealing On The Contact Resistance Of Aluminum On A P-Type Substrate, Shrey Shah, George Patrick Watson

Protocols and Reports

Aluminum contacts are widely used to form both ohmic and rectifying contacts. The process to form these contacts involves annealing, thus it is important to study the effect of annealing on the electrical properties of the contacts. Here, we present a way to measure the contact resistance of aluminum contacts formed on a p-type silicon substrate. It was found the contact resistivity decreased by an average of 18%. It was thus found that annealing at 400°C in a forming gas environment improves the electrical properties of aluminum contacts.


Contamination Of Coupling Glass And Performance Evaluation Of Protective System In Vacuum Laser Beam Welding, Yongki Lee, Jason Cheon, Byung-Kwon Min, Cheol-hee Kim 2019 Korea Institute of Industrial Technology

Contamination Of Coupling Glass And Performance Evaluation Of Protective System In Vacuum Laser Beam Welding, Yongki Lee, Jason Cheon, Byung-Kwon Min, Cheol-Hee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

Vacuum laser beam welding enables deeper penetration depth and welding stability than atmospheric pressure laser welding. However, contaminated coupling glass caused by welding fumes in the vacuum space reduces laser transmittance, leading to inconsistent penetration depth. Therefore, a well-designed protective system is indispensable. Before designing the protective system, the contamination phenomenon was quantified and represented by a contamination index, based on the coupling glass transmittance. The contamination index and penetration depth behavior were determined to be inversely proportional. A cylindrical protective system with a shielding gas supply was proposed and tested. The shielding gas jet provides pressure-driven contaminant suppression and ...


Effect Of Ion Implantation On The Mechanical Properties Of The Grain And Grain Boundary Regions Of Inconel X750, Maisaa Nezar Tawfeeq 2019 The University of Western Ontario

Effect Of Ion Implantation On The Mechanical Properties Of The Grain And Grain Boundary Regions Of Inconel X750, Maisaa Nezar Tawfeeq

Electronic Thesis and Dissertation Repository

Annulus gas spacers in CANada Deuterium Uranium (CANDU) nuclear reactors are made from the heat-treated Inconel X750 Nickel-based alloy. This alloy is designed to have high strength and creep resistance at elevated temperature. Unlike other reactor designs, the CANDU reactor has a high thermal neutron fluence, which results in an enhancement of the radiation damage and the internal production of helium and hydrogen. They are thus susceptible to microstructural instability and mechanical property degradation with time. Studies of ex-service spacers have indicated that they display intergranular embrittlement and lower ultimate tensile strength compared to nonirradiated Inconel X750. The primary degradation ...


Improved Plasticity Of Inconel 718 Superalloy Fabricated By Selective Laser Melting Through A Novel Heat Treatment Process, X. Li, J. J. Shi, G. H. Cao, Alan M. Russell, Z. J. Zhou, C. P. Li, G. F. Chen 2019 Shanghai University

Improved Plasticity Of Inconel 718 Superalloy Fabricated By Selective Laser Melting Through A Novel Heat Treatment Process, X. Li, J. J. Shi, G. H. Cao, Alan M. Russell, Z. J. Zhou, C. P. Li, G. F. Chen

Materials Science and Engineering Publications

When Inconel 718 alloy is fabricated by selective laser melting and treated by traditional homogenization plus double aging heat treatment (HA), its strength improves greatly, but ductility decreases. A novel heat treatment (NHT) including higher temperature homogenization at 1150 °C for 2 h and one-time lower temperature aging treatment at 700 °C for 12 h is developed, which can overcome the strength-plasticity trade-off of Inconel 718 alloy. The results show that recrystallized grains with annealing twins and ultrafine strengthening phases form in the specimen subjected to the NHT. These microstructures differ from those in as-built and conventional heat-treated samples. Especially ...


In Situ Tem Study Of The Amorphous-To-Crystalline Transition During Dielectric Breakdown In Tio2 Film, Xinchun Tian, Chloe Cook, Wei Hong, Tao Ma, Geoff L. Brennecka, Xiaoli Tan 2019 Iowa State University

In Situ Tem Study Of The Amorphous-To-Crystalline Transition During Dielectric Breakdown In Tio2 Film, Xinchun Tian, Chloe Cook, Wei Hong, Tao Ma, Geoff L. Brennecka, Xiaoli Tan

Materials Science and Engineering Publications

Dielectric breakdown of oxides is a main limiting factor for improvement of the performance of electronic devices. Present understanding suggests that defects produced by intense voltage accumulate in the oxide to form a percolation path connecting the two electrodes and trigger the dielectric breakdown. However, reports on directly visualizing the process at nanoscale are very limited. Here, we apply in situ transmission electron microscopy to characterize the structural and compositional changes of amorphous TiO2 under extreme electric field (~100 kV/mm) in a Si/TiO2/W system. Upon applying voltage pulses, the amorphous TiO2 gradually transformed to crystalline sub-stoichiometric rutile ...


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