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2017

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Articles 151 - 180 of 615

Full-Text Articles in Materials Science and Engineering

Studying Chromium And Nickel Equivalency To Identify Viable Additive Manufacturing Stainless Steel Chemistries, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley Aug 2017

Studying Chromium And Nickel Equivalency To Identify Viable Additive Manufacturing Stainless Steel Chemistries, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Chromium and nickel equivalency modeling has long been used in welding to determine the weldability of steel chemistries. A study was conducted to determine the applicability of Cr-Ni modeling to the additive manufacturing process. Many AM methods involve rapid solidification of small melt pools, similar to welding. Chemistries with varying Cr/Ni ratios were selected for use in a selective laser melting process and modeled using known models. Initial results indicate that the standard "safe welding zone" may not directly apply to additive manufacturing. The capability to build with chemistries outside the weldability “safe zone” could result in improved and varied …

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Aluminum Matrix Syntactic Foam Fabricated With Additive Manufacturing, M. Spratt, Joseph William Newkirk, K. Chandrashekhara Aug 2017

Aluminum Matrix Syntactic Foam Fabricated With Additive Manufacturing, M. Spratt, Joseph William Newkirk, K. Chandrashekhara

Materials Science and Engineering Faculty Research & Creative Works

Syntactic foams are lightweight structural composites with hollow reinforcing particles embedded in a soft matrix. These materials have applications in transportation, packaging, and armor due to properties such as relatively high specific stiffness, acoustic dampening, and impact absorption. Aluminum matrices are the most widely studied of metal matrix syntactic foams, but there is little to no research in regards to processing the foams with additive manufacturing. It is theorized that the fast cooling rates and limited kinetic energy input of additive could reduce two issues commonly associated with processing syntactic foams: microsphere flotation in the melt and microsphere fracture during …

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Effects Of Area Fraction And Part Spacing On Degradation Of 304l Stainless Steel Powder In Selective Laser Melting, Cairlin S. Kriewall, Austin T. Sutton, Sreekar Karnati, Joseph William Newkirk, Ming-Chuan Leu Aug 2017

Effects Of Area Fraction And Part Spacing On Degradation Of 304l Stainless Steel Powder In Selective Laser Melting, Cairlin S. Kriewall, Austin T. Sutton, Sreekar Karnati, Joseph William Newkirk, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

In selective laser melting (SLM) systems, a large portion of powder remains unconsolidated and therefore recycling powder could make SLM more economical. Currently, a lack of literature exists specifically targeted at studying the reusability of powder. Furthermore, the definition of powder reusability is complex since powder degradation depends on many factors. The goal of the current research is to investigate the effects of area fraction and part spacing on the degradation of 304L powder in SLM. An experimental study was conducted where various area fractions and part distances were chosen and powder characterization techniques for determination of particle size distributions, …

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Bonding Of 304l Stainless Steel To Cast Iron By Selective Laser Melting, Baily Thomas, Austin T. Sutton, Ming-Chuan Leu, Nikhil Doiphode Aug 2017

Bonding Of 304l Stainless Steel To Cast Iron By Selective Laser Melting, Baily Thomas, Austin T. Sutton, Ming-Chuan Leu, Nikhil Doiphode

Mechanical and Aerospace Engineering Faculty Research & Creative Works

While cast iron is widely used in industry, a major limitation is the weldability of a dissimilar material onto cast iron due to hot cracking as a result of lack of ductility from graphite flakes. Consequently, a significant amount of preheat is often employed to reduce the cooling rate in the fusion zone, which, however, may lead to distortion of the welded parts. A potential remedy could be the Selective Laser Melting (SLM) process, where only small melt pools are created and thus the overall energy input is reduced. The present paper describes an investigation of the SLM process to …

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Building Zr-Based Metallic Glass Part On Ti-6al-4v Substrate By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai Aug 2017

Building Zr-Based Metallic Glass Part On Ti-6al-4v Substrate By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Through using Zr intermediate layers, Zr52.5Ti5Al10Ni14.6Cu17.9 metallic glass (MG) parts are successfully built on Ti-6Al-4V substrates by laser-foil-printing (LFP) additive manufacturing technology in which MG foils are laser welded layer-by-layer onto the substrate. The printed MG part is free of porosity, cracking and crystallization; additionally, its glass transition temperature, crystallization temperature, micro-hardness, and tensile strength are very similar to the original MG material. The Zr intermediate layers are aimed at preventing direct interaction between the first layer of MG foil and the Ti substrate; otherwise, the welded MG foils would peel …

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Mechanical Properties Of 304l Parts Made By Laser-Foil-Printing Technology, Chia-Hung Hung, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai Aug 2017

Mechanical Properties Of 304l Parts Made By Laser-Foil-Printing Technology, Chia-Hung Hung, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser-Foil-Printing (LFP) is a novel laminated object manufacturing process for metal additive manufacturing. It fabricates three-dimensional metal parts by using a dual-laser system to weld and cut metal foils layer by layer. A main advantage of LFP is the higher cooling rate compared to powder-based laser additive manufacturing processes due to the thermal conductivity difference between foil and powder. This study focuses on the mechanical properties of 304L stainless steel parts built by the LFP process. The experimental results indicate that the yield strength and ultimate tensile strength of LFP fabricated 304L SS parts are higher by 9% and 8% …

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Influence Of Gage Length On Miniature Tensile Characterization Of Powder Bed Fabricated 304l Stainless Steel, Sreekar Karnati, Jack L. Hoerchler, Frank W. Liou, Joseph William Newkirk Aug 2017

Influence Of Gage Length On Miniature Tensile Characterization Of Powder Bed Fabricated 304l Stainless Steel, Sreekar Karnati, Jack L. Hoerchler, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Miniature tensile specimens with varying aspect ratios were fabricated from 304L stainless steel (SS) made using powder bed additive manufacturing (AM) process. The tensile characteristics measured from these specimens were analyzed to assess the impact of gage length. The study found no impact upon varying gage length on yield and ultimate strength measurements. However, a significant impact was observed on strain measurements. This data was also used to perform Weibull statistics to estimate the stochastic performance of the material. Fractography was performed to visually identify the types of flaws. A comparative study with specimens fabricated from cold rolled annealed 304 …

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Investigation Of Build Strategies For A Hybrid Manufacturing Process Progress On Ti-6al-4v, Lei Yan, Leon Hill, Frank W. Liou, Joseph William Newkirk Aug 2017

Investigation Of Build Strategies For A Hybrid Manufacturing Process Progress On Ti-6al-4v, Lei Yan, Leon Hill, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The various processing parameters of a hybrid manufacturing process, including deposition and machining, is being investigated with a Design of Experiment (DoE). The intent was to explore the effect of different build strategies on the final part’s Vickers hardness, tensile test, fatigue life, and microstructure. From this experiment, the processing parameters can be linked to various mechanical properties. This will lead to the ability to create a combination of deposition and machining parameters, which will result in improved mechanical properties.

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A Two-Dimensional Simulation Of Grain Structure Growth Within Substrate And Fusion Zone During Direct Metal Deposition, Jingwei Zhang, Wei Li, Frank W. Liou, Joseph William Newkirk Aug 2017

A Two-Dimensional Simulation Of Grain Structure Growth Within Substrate And Fusion Zone During Direct Metal Deposition, Jingwei Zhang, Wei Li, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a predictive model based on a cellular automaton (CA)-finite element (FE) method has been developed to simulate thermal history and microstructure evolution during metal solidification for a laser-based additive manufacturing process. The macroscopic FE calculation that is validated by thermocouple experiment is designed to update the temperature field and a high cooling rate. A cellular automata-finite element (CAFE) method is developed to describe grain growth in the fusion zone. In the mesoscopic CA model, heterogeneous nucleation sites, grain growth orientation and rate, epitaxial growth, remelting of preexisting grains, metal addition, grain competitive growth, and columnar to equiaxed …

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Analysis Of Variable Insensitive Friction Stir Welding Parameters, Robert L. Marrero Jr Aug 2017

Analysis Of Variable Insensitive Friction Stir Welding Parameters, Robert L. Marrero Jr

LSU New Orleans Theses and Dissertations

Friction Stir Welding (FSW) was used to perform a Design of Experiment (DOE) to determine the welding parameters effects on yielding consistent mechanical properties across the length of the weld. The travel speed was varied across set forge force and RPM conditions, to find a dataset that will yield consistent mechanical properties independent of the travel speed. Six different welds were completed on two different aluminum panels, the advancing side being Aluminum alloy 2195-T8 at a thickness of .350”, with the retreating side being Aluminum alloy 2219-T851 with a gauge thickness of .360”. A Left-hand Right-hand self-reacting pin tool was …

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Influence Of Adsorbed And Nonadsorbed Polymer Additives On The Viscosity Of Magnesium Oxide Suspensions, Lisa R. Murray, Jason E Bice, Emily G. Soltys, Christopher Perge, Sebastien Manneville, Kendra Erk Aug 2017

Influence Of Adsorbed And Nonadsorbed Polymer Additives On The Viscosity Of Magnesium Oxide Suspensions, Lisa R. Murray, Jason E Bice, Emily G. Soltys, Christopher Perge, Sebastien Manneville, Kendra Erk

School of Materials Engineering Faculty Publications

Adsorbed polymer additives have been employed to reduce water content and improve cement workability through lowering viscosity, but the influence of over-dosage and the presence of nonadsorbed chains have yet to be fully understood. Model magnesium oxide (MgO) suspensions were used to investigate the potential processing effect of “free” chain concentration on cementitious mixtures. The rheological impact of the free chains was measured through incorporation of nonadsorbing poly(ethylene glycol) (PEG) to suspensions stabilized with an adsorbed comb-polymer superplasticizer. Analyses of the rheological data, that showed viscosity-increases and viscosity-reduction due to free PEG concentrations revealed a transition from depletion flocculation to …

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Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming-Chuan Leu, Greg Hilmas Aug 2017

Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. This paper presents a further development of this process and focuses on fabricating 3 mol% yttria-stabilized zirconia (3YSZ) components that cannot be fabricated without using support structures. The 3YSZ paste is deposited through the main nozzle, and a polycaprolactone (PCL) pellet feedstock is melted and deposited through an auxiliary nozzle to build support structures. After a green part is printed and dried, the support structures are removed by heating the part to ~70 ⁰C to melt the PCL. The part is then …

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Metrology Of Dna Arrays By Super-Resolution Microscopy, Christopher M. Green, Kelly Schutt, Noah Morris, Reza M. Zadegan, William L. Hughes, Wan Kuang, Elton Graugnard Aug 2017

Metrology Of Dna Arrays By Super-Resolution Microscopy, Christopher M. Green, Kelly Schutt, Noah Morris, Reza M. Zadegan, William L. Hughes, Wan Kuang, Elton Graugnard

Materials Science and Engineering Faculty Publications and Presentations

Recent results in the assembly of DNA into structures and arrays with nanoscale features and patterns have opened the possibility of using DNA for sub-10 nm lithographic patterning of semiconductor devices. Super-resolution microscopy is being actively developed for DNA-based imaging and is compatible with inline optical metrology techniques for high volume manufacturing. Here, we combine DNA tile assembly with state-dependent super-resolution microscopy to introduce crystal-PAINT as a novel approach for metrology of DNA arrays. Using this approach, we demonstrate optical imaging and characterization of DNA arrays revealing grain boundaries and the temperature dependence of array quality. For finite arrays, analysis …

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Modeling Micro-Porous Surfaces For Secondary Electron Emission Control To Suppress Multipactor, James M. Sattler, Ronald Coutu Jr., Robert A. Lake, Tod V. Laurvick, Tyson C. Back, Steven. B. Fairchild Aug 2017

Modeling Micro-Porous Surfaces For Secondary Electron Emission Control To Suppress Multipactor, James M. Sattler, Ronald Coutu Jr., Robert A. Lake, Tod V. Laurvick, Tyson C. Back, Steven. B. Fairchild

Faculty Publications

This work seeks to understand how the topography of a surface can be engineered to control secondary electron emission (SEE) for multipactor suppression. Two unique, semi-empirical models for the secondary electron yield (SEY) of a micro-porous surface are derived and compared. The first model is based on a two-dimensional (2D) pore geometry. The second model is based on a three-dimensional (3D) pore geometry. The SEY of both models is shown to depend on two categories of surface parameters: chemistry and topography. An important parameter in these models is the probability of electron emissions to escape the surface pores. This probability …

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Microstructure Evolution During Compaction Of Powder Blends, Ayush Giri, Marcial Gonzalez, Yasasvi Bommire Aug 2017

Microstructure Evolution During Compaction Of Powder Blends, Ayush Giri, Marcial Gonzalez, Yasasvi Bommire

The Summer Undergraduate Research Fellowship (SURF) Symposium

Powder compaction is a manufacturing technology used to transform powder particles into a solid material with unique anisotropic microstructure and low porosity. It is widely used by pharmaceutical companies to manufacture tablets with desired properties. These properties are the result of the microstructure obtained during the compaction process. Therefore, it is imperative to understand the mechanics underneath the constituent granular particles that eventually contribute to properties of the manufactured tablets. Computational simulation tools have been developed in the past to study powder compaction for pharmaceutical tablets. However, most of the already existing tools limit their scope to study individual particles …

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Investigating Tantalum As A Plasma-Facing Component For Nuclear Fusion Reactors, Arvind Sundaram, Jitendra K. Tripathi, Theodore J. Novakowski, Ahmed Hassanein Ph. D. Aug 2017

Investigating Tantalum As A Plasma-Facing Component For Nuclear Fusion Reactors, Arvind Sundaram, Jitendra K. Tripathi, Theodore J. Novakowski, Ahmed Hassanein Ph. D.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is a potential source for producing unlimited environment-friendly energy. Tungsten (W) is selected as the primary candidate material for plasma facing component in nuclear fusion reactors due to its high melting temperature (3695 K), low sputtering erosion yield and strong mechanical properties. However, recent investigations on W have confirmed that it undergoes severe surface morphology changes during low energy He plasma and/or ion irradiation similar to a harsh fusion environment. Additionally, our previous studies indicate that tantalum (Ta) may show better resistance to the harsh radiation environment and is therefore worthy of investigation. Hydrogen retention properties, specifically deuterium …

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Understanding Powder Compaction With Single Particle Measurements, Wentao Chen, Ankit Agarwal, Marcial Gonzalez Aug 2017

Understanding Powder Compaction With Single Particle Measurements, Wentao Chen, Ankit Agarwal, Marcial Gonzalez

The Summer Undergraduate Research Fellowship (SURF) Symposium

Powder compaction is the process of transforming granular media into a solid body with a high relative density (low porosity) and a unique anisotropic microstructure. It is critical to understand the physical mechanisms of the compaction process in order to identify powder properties and optimal process parameters for achieving desired properties of the final product. Tools that can simulate particle rearrangement and deformation during the compaction process are usually developed to guide such fundamental understanding. This study aims at understanding powder compaction using particle mechanics approach. Specifically, it employs the nonlocal contact formulation to predict the contact behavior of a …

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Simulating Dynamic Failure Of Polymer-Bonded Explosives Under Periodic Excitation, Rachel Kohler, Camilo Duarte Cordon, Marisol Koslowski Aug 2017

Simulating Dynamic Failure Of Polymer-Bonded Explosives Under Periodic Excitation, Rachel Kohler, Camilo Duarte Cordon, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

Accidental mishandling of explosive materials leads to thousands of injuries in the US every year. Understanding the mechanisms behind the detonation process is crucial to prevent such accidents. In polymer-bonded explosives (PBX), high-frequency mechanical excitation generates thermal energy and can lead to an increase in temperature and vapor pressure, and potentially the initiation of the detonation process. However, the mechanisms behind this energy release, such as the effects of dynamic fracture and friction, are not well understood. Experimental data is difficult to collect due to the different time scales of reactions and vibrations, so research is aided by running simulations …

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Modelling Catalytic Structures With Python And Ase, Tommie L. Day, Peilin Liao, Pilsun Yoo Aug 2017

Modelling Catalytic Structures With Python And Ase, Tommie L. Day, Peilin Liao, Pilsun Yoo

The Summer Undergraduate Research Fellowship (SURF) Symposium

Voltaic cells hold great potential as a source of clean electricity generation. These fuel sources are more efficient than combustion engines, and they do not produce environmentally harmful by-products. The electrochemical reaction which occurs within the cell is typically catalyzed by platinum, which increases the cost. The search for a better performing, less expensive catalyst is hindered by the lack of a complete, predictive theory of catalysis. Using Quantum Espresso and the Atomic Simulation Environment library for Python, we created a tool for nanoHUB.org which can visually and computationally model catalytic surfaces. This tool can simulate nanoparticles and metallic surfaces …

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Irradiation-Induced Nanocluster Evolution, Didier Ishimwe, Matthew J. Swenson, Janelle P. Wharry Aug 2017

Irradiation-Induced Nanocluster Evolution, Didier Ishimwe, Matthew J. Swenson, Janelle P. Wharry

The Summer Undergraduate Research Fellowship (SURF) Symposium

Oxide dispersion strengthened steel (ODS) and commercial ferritic-martensitic (F-M) alloys are widely accepted candidate structural materials for designing advanced nuclear reactors. Nanoclusters embedded in the steel matrix are key microstructural features of both alloy types. Irradiation from nuclear fusion and fission affects the morphology of these nanoparticles, altering the performance of the alloys and potentially decreasing their usable lifetime. Thus, it is important to understand the effect of irradiation on these nanoparticles in order to predict long-term nuclear reactor performance. It was found that the evolution of nanoclusters in each material is different depending on the experimental irradiation parameters. The …

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Core-Shell Copper And Nickel Nanofoam: Uniform Electroplating And Properties, Hassan Zbib, David Bahr Aug 2017

Core-Shell Copper And Nickel Nanofoam: Uniform Electroplating And Properties, Hassan Zbib, David Bahr

The Summer Undergraduate Research Fellowship (SURF) Symposium

Characterizing materials on the nanoscale is a key factor to enhance nanotechnology in diverse applications, ranging from electronics to energy fields. However, controlling the structure of the material at the nanoscale or mimicking the nanoscale features of a structure that already exists requires linking processing conditions to the nanostructure. This work focuses on solids that show porous patterns at the nano-micro scale; these are often called cellular solids and classified into two categories: honeycombs and foams. This study focuses on nanofoams; with ligament dimensions in the sub-micron scale. Electrospinning has been developed to produce nanofoam structures of polymers with controlled …

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Structure-Force Field Generator For Molecular Dynamics Simulations, Carlos M. Patiño, Lorena Alzate, Alejandro Strachan Aug 2017

Structure-Force Field Generator For Molecular Dynamics Simulations, Carlos M. Patiño, Lorena Alzate, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Atomistic and molecular simulations have become an important research field due to the progress made in computer performance and the necessity of new and improved materials. Despite this, first principle simulations of large molecules are still not possible because the high computational time and resources required. Other methods, such as molecular dynamics, allow the simplification of calculations by defining energy terms to describe multiple atom interactions without compromising accuracy significantly. A group of these energy terms is called a force field, and each force field has its own descriptions and parameters. The objective of this project was to develop a …

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Cylindrical Shell Based Phase Transforming Cellular Materials: Designing A Recoverable Energy Dissipating Material, Gordon F. Jarrold, David Restrepo, Nilesh Mankame, Pablo Zavattieri Aug 2017

Cylindrical Shell Based Phase Transforming Cellular Materials: Designing A Recoverable Energy Dissipating Material, Gordon F. Jarrold, David Restrepo, Nilesh Mankame, Pablo Zavattieri

The Summer Undergraduate Research Fellowship (SURF) Symposium

Energy dissipating materials are used in a variety of impact events to protect more important parts of a system; one example of this is a football player’s helmet protecting a brain. A major drawback to classic energy dissipating materials however is that they dissipate energy through plastic deformation, meaning that after a single use, permanent deformations will prevent the material from being reusable to the same capacity as initially. We have designed a 1D cellular material in which geometric phase transformations in cylindrical shell elements are the primary energy dissipating mechanism, allowing for recoverability after use while keeping high energy …

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Effect Of Particle Interactions On Powder Flow Behavior, Ivana A. Penagos, Carolina P. Mora, Teresa Carvajal Aug 2017

Effect Of Particle Interactions On Powder Flow Behavior, Ivana A. Penagos, Carolina P. Mora, Teresa Carvajal

The Summer Undergraduate Research Fellowship (SURF) Symposium

The study of powder flow behavior is essential for the development of processing technologies in many industries. In fact, powders have a major function in diverse types of manufacturing, such as pharmaceuticals, foods, chemicals, materials, minerals and cosmetics. This leads to an increasing demand for the development of reliable methods to assess powder flow problems in industry. This research intends to provide a general insight into how surface interactions and particle properties may alter powder flowability. The materials used for this study were lactose, starch, milk powder, cocoa and chocolate. These vary in their interparticle forces as well as on …

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Atomistic Simulations Of Novel Nanoscale Semiconductor Devices: Resistance Switches And Two-Dimensional Transistors, Joseph P. Anderson, Mahbubul Islam, David Guzman, Alejandro Strachan Aug 2017

Atomistic Simulations Of Novel Nanoscale Semiconductor Devices: Resistance Switches And Two-Dimensional Transistors, Joseph P. Anderson, Mahbubul Islam, David Guzman, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

As transistors get smaller, we are achieving record levels of memory density. However, there is a limit to how small transistors can be made before their functionality breaks down. Thus alternatives to traditional transistor technology are needed. The two such technologies we examined are: resistance switching devices, which reversibly grow metal filaments through a dielectric, and two-dimensional transistors, which are capable of breaking through the scalability limit of traditional transistors. In order to design resistance switching devices which create filaments with some level of consistency, the dynamics of the filament formation need to be explored. Herein we model this process …

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Study Of Persistent Slip Bands Formed By Low Cycle Fatigue On Nickel-Based Superalloys At Room Temperature, Anjola Uprety, Sae Matsunaga, Michael S. Titus Dr., Michael D. Sangid Dr., Alberto W. Mello Dr. Aug 2017

Study Of Persistent Slip Bands Formed By Low Cycle Fatigue On Nickel-Based Superalloys At Room Temperature, Anjola Uprety, Sae Matsunaga, Michael S. Titus Dr., Michael D. Sangid Dr., Alberto W. Mello Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

The ability of Ni-based superalloys to withstand temperatures in excess of 11000C makes them useful for applications in the hottest components in jet engines, gas turbines, and thrust engines. Increasing the efficiency of these gas turbine engines helps to reduce the fossil fuel consumption and the production of greenhouse gasses. A common mode of failure in these Ni-based superalloys is low cycle fatigue, in which narrow regions of high dislocation density, which are known as persistent slip bands (PSBs), can develop and lead to crack initiation. A detailed understanding of the formation and structure of PSBs has eluded …

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Comparison Of Pm-Hip To Cast Alloy 625 For Nuclear Applications, Alexander L. Bullens, Keyou Mao, Janelle P. Wharry, Esteban Bautista Aug 2017

Comparison Of Pm-Hip To Cast Alloy 625 For Nuclear Applications, Alexander L. Bullens, Keyou Mao, Janelle P. Wharry, Esteban Bautista

The Summer Undergraduate Research Fellowship (SURF) Symposium

PM-HIP, or Powder Metallurgy and Hot Isostatic Pressing, metals have been a low cost alternative to forged and cast structural metals within various industries. The nuclear industry has recently developed interest in PM-HIP alloys, but further research needs to be done to quantify their mechanical properties and characterize the microstructure. Specifically, we must understand the mechanical and microstructural evolution of PM-HIP materials after long-term operation at the elevated temperatures that PM-HIP components will experience in service. We focus on Ni-base alloy Inconel 625, and compare the PM-HIP version to the cast version. Our methodology consists of annealing samples to various …

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Improving Methods Of Doping On Black Phosphorus, Yuqin Duan, Adam Charnas, Jingkai Qin, Peide Ye Aug 2017

Improving Methods Of Doping On Black Phosphorus, Yuqin Duan, Adam Charnas, Jingkai Qin, Peide Ye

The Summer Undergraduate Research Fellowship (SURF) Symposium

Black phosphorus (BP) is a 2D semiconducting material with high carrier mobility. It is usually p-type due to oxidation states near its valence band. Although achieved through other growth methods, n-type doping has not yet been accomplished through the modern chemical vapor transport (CVT) growth method. To address this issue, small amounts of tellurium were added to Red Phosphorus to act as a dopant during the CVT growth process in addition to tin(Sn) and tin(IV) iodide, which facilitate growth. The chemicals are heated up to 600°C and precisely cooled in a 21-hour process, during which BP crystals should form. After …

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Spectroscopic Contrast Of Diarylethene Molecules On Octanethiol Monolayer, Arramel Arramel, Tibor Kudernac, Nathalie Katsonis, Bernard Lucas Feringa, Bart Jan Van Wees Aug 2017

Spectroscopic Contrast Of Diarylethene Molecules On Octanethiol Monolayer, Arramel Arramel, Tibor Kudernac, Nathalie Katsonis, Bernard Lucas Feringa, Bart Jan Van Wees

Makara Journal of Technology

We present a systematic scanning tunneling microscopy (STM) study of bias-dependent imaging of disulfur diarylethene (2S-DE) molecules on octanethiol (C8) monolayer at room temperature. In a rigid confinement of the C8 matrix, we did not observe any significant variation in the appearance of the 2S-DE. On the contrary, a reversal in the apparent height of the 2S-DE was present when the molecule was situated on a gold vacancy island. We attributed this finding to the presence of a new electronic state that became accessible for a tunneling event. In addition, the C8 surface structure underwent a reversible phase transformation from …

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Residual Stress Measurements On The Tig Weld Joint Of 57fe15cr25ni Austenitic Steel For Structural Material Applications By Means X-Ray Diffraction Techniques, Parikin Parikin, Agus Hadi Ismoyo, Riza Iskandar, Arbi Dimyati Aug 2017

Residual Stress Measurements On The Tig Weld Joint Of 57fe15cr25ni Austenitic Steel For Structural Material Applications By Means X-Ray Diffraction Techniques, Parikin Parikin, Agus Hadi Ismoyo, Riza Iskandar, Arbi Dimyati

Makara Journal of Technology

Measurements of residual stress on the 57Fe25Cr15Ni steel plate with no-filler TIG-welding process were carried out. This work was conducted to determine the nature of weld ability in synthesized steel. The bulks were formed in a dimension of 30x20x7 mm3 to ease data retrieval. Results show that the largest residual stress occurred in the weld metal area, amounting to 82.40 MPa with lattice stretching of 0.18%. Conversely, the values decreased to 65.92 MPa and a stretch of 0.14% in the HAZ area. This residual stress is a tensile stress that can reduce the mechanical strength of the material since it …

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