Materials Science and Engineering Commons^™

Simulation Of The Relaxation Potential Profile Of An Ac-Dc-Ac Test, Kerry N. Allahar, Michael F. Hurley, Erik D. Sapper, Darryl P. Butt

Materials Science and Engineering Faculty Publications and Presentations

The relaxation period of the accelerated ac-dc-ac test for coatings is associated with the transient electrochemistry that occurs when the immersed coated system is allowed to return to a stable open-circuit condition after being subjected to a cathodic potential. A mathematical model of the transient electrochemistry that occurs during this relaxation period is presented for coated aluminum. Expressions for the corrosion potential and corrosion current as functions of the local pH at the metal-coating interface were developed using reported experimental results. These expressions enabled the simulation of the transient electrochemistry under the constraint of balanced anodic and cathodic current densities. …

Identification Of Silver And Palladium In Irradiated Triso Coated Particles Of The Agr-1 Experiment, I. J. Van Rooyen, T. M. Lillo, Y. Q. Wu

Materials Science and Engineering Faculty Publications and Presentations

Evidence of the release of certain metallic fission products through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at the Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes.

Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy-Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), …

Correlation Between The Microstructure And Mechanical Properties Of Irradiated Fe-9cr Ods, M. Swenson, C. Dolph, J. Wharry

Materials Science and Engineering Faculty Publications and Presentations

The growing global demand for energy will increasingly call upon fusion reactors and Generation IV nuclear fission reactors to supply safe and reliable energy worldwide. Ferritic/martensitic (F/M) alloys are leading candidates for structural components in these reactors because of their high strength, dimensional stability, and low activation. In novel reactor concepts, these materials will be subject to extreme operating conditions, accumulating doses of irradiation up to a few hundred displacements per atom (dpa) at temperatures as high as 600°C. Oxide dispersion strengthened (ODS) F/M alloys containing a dispersion of Y-Ti-0 nanoclusters have been developed to operate at even higher temperatures.

Enhanced Dna Sensing Via Catalytic Aggregation Of Gold Nanoparticles, Herbert M. Huttanus, Elton Graugnard, Bernard Yurke, William B. Knowlton, Wan Kuang, William L. Hughes, Jeunghoon Lee

Materials Science and Engineering Faculty Publications and Presentations

A catalytic colorimetric detection scheme that incorporates a DNA-based hybridization chain reaction into gold nanoparticles was designed and tested. While direct aggregation forms an inter-particle linkagefrom only one target DNA strand, catalytic aggregation forms multiple linkages from a single target DNA strand. Gold nanoparticles were functionalized with thiol-modified DNA strands capable of undergoing hybridization chain reactions. The changes in their absorption spectra were measured at different times and target concentrations and compared against direct aggregation. Catalytic aggregation showed a multifold increase in sensitivity at low target concentrations when compared to direct aggregation. Gelelectrophoresis was performed to compare DNA hybridization reactions …

Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston

Boise State University Theses and Dissertations

Inconel 617 is a candidate material for use in the intermediate heat exchanger of the Next Generation Nuclear Plant. Because of the high temperatures and the fluctuations in stress and temperature, the fatigue behavior of the material is important to understand. The goal of this study was to determine the influences of the microstructure during fatigue crack propagation. For this investigation, Inconel 617 compact tension samples, fatigue tested by Julian Benz at the Idaho National Laboratory, were obtained. The testing conditions included two environments at 650 °C (lab air and impure-He) and varied testing parameters including: loading waveform (triangular, trapezoidal), …

Impact Of Alkaline Doping And Reducing Conditions On Lafeo3, Geoffrey L. Beausoleil

Boise State University Theses and Dissertations

Efficient and reliable materials for gas separation, syngas production, and hybrid nuclear power plants must be capable of reliably operating at a high-temperature range of 700-1000°C and under exposure to highly oxidizing and reducing conditions. Candidate materials for these applications include alkaline metal doped lanthanum ferrite.

In the first study, the impact of A site substitution by different alkaline metals on lanthanum ferrite (LMF, M=Ca, Sr, and Ba) was investigated. The study focused on thermal expansion near the Néel transition temperature and a magneto-elastic contribution to thermal expansion was identified for each sample. Iron oxidation, Fe³⁺ to Fe^{4+ …}

Unification Of The Negative Electrocaloric Effect In Bi1/2Na1/2Tio3-Batio3 Solid Solutions By Ba1/2Sr1/2Tio3 Doping, Sarir Uddin, Guang-Ping Zheng, Yaseen Iqbal, Rick Ubic, Junhe Yang

Materials Science and Engineering Faculty Publications and Presentations

The microscopic mechanisms of the negative electrocaloric effect (ECE) of the single-phase (1−x)(0.94Bi_1/2Na_1/2TiO₃-0.06BaTiO₃)-xBa_1/2Sr_1/2TiO₃ (BNT-BT-BST) perovskite solid solutions fabricated via the sol-gel technique are explored in this study. Dielectric and mechanical relaxation analyses are employed to investigate the ferroelectric and structural transitions of the samples. The electrocaloric properties of the samples were measured by thermodynamics Maxwell relations. The difference between the depolarization temperature (T_d) and the maximum dielectric constant temperature (T_m) was found to decrease with increasing BST content. Doping with BST stabilized the …

A Systematic Study Of Radiation-Induced Segregation In Ferritic–Martensitic Alloys, Janelle P. Wharry, Gary S. Was

Materials Science and Engineering Faculty Publications and Presentations

A systematic approach to measuring radiation-induced segregation (RIS) was used on four ferritic–martensitic (F–M) alloys: T91, HCM12A, HT9, and a Fe–9Cr model alloy, irradiated with 2.0 MeV protons over a range of doses (1–10 dpa) and temperatures (300–700°C). The experimental conditions are established so as to isolate the dependence of RIS on the experimental parameters: temperature, dose and bulk composition. RIS is measured at prior austenite grain boundaries (PAGBs) using the STEM/EDX technique. Chromium is found to enrich at PAGBs in all conditions with the exception being T91 irradiated to 3 dpa at 700°C. The magnitude of enrichment is small …

Magnetic Interaction Reversal In Watermelon Nanostructured Cr-Doped Fe Nanoclusters, Maninder Kaur, Qilin Dai, Mark Bowden, Mark H. Engelhard, Yaqiao Wu, Jinke Tang, You Qiang

Materials Science and Engineering Faculty Publications and Presentations

Cr-doped core-shell Fe/Fe-oxide nanoclusters (NCs) were synthesized at varied atomic percentages of Cr from 0 at. % to 8 at. %. The low concentrations of Cr (%) were selected in order to inhibit the complete conversion of the Fe-oxide shell to Cr₂O₃ and the Fe core to FeCr alloy. The magnetic interaction in Fe/Fe-oxide NCs (~25 nm) can be controlled by antiferromagnetic Cr-dopant. We report the origin of σ-FeCr phase at very low Cr concentration (2 at. %) unlike in previous studies, and the interaction reversal from dipolar to exchange interaction in watermelon-like Cr-doped core-shell NCs.

High Field Breakdown Characteristics Of Carbon Nanotube Thin Film Transistors, Man Prakash Gupta, Ashkan Behnam, Feifei Lian, David Estrada, Eric Pop, Satish Kumar

Materials Science and Engineering Faculty Publications and Presentations

The high field properties of carbon nanotube (CNT) network thin film transistors (CN-TFTs) are important for their practical operation, and for understanding their reliability. Using a combination of experimental and computational techniques we show how the channel geometry (length L_C and width W_C) and network morphology (average CNT length L_t and alignment angle distribution θ) affect heat dissipation and high field breakdown in such devices. The results suggest that when W_C ≥ L_t, the breakdown voltage remains independent of W_C but varies linearly with L_C. The breakdown power varies …

Magnetic And Structural Properties Of Ni-Mn-Ga Films Produced Via Physical Vapor Tri-Deposition, Christopher Kimo Wilson

Boise State University Theses and Dissertations

The structural, thermal, magnetic, and mechanical properties of Ni-Mn-Ga magnetic shape-memory alloys depend strongly on composition. Compositions of sputter deposited films differ from the composition of the single alloy targets from which they originate, where the composition change depends on sputter parameters. Films produced via physical vapor deposition from single alloy targets have sound film-substrate adhesion and film uniformity, however, accurate control of composition is difficult. Tri-sputter deposition from multiple targets allows the flexibility of varying deposition rates and film compositions. A robust procedure with three targets (nickel, nickel-gallium, and manganese) was developed to deposit Ni-Mn-Ga films on silicon with …

Predicting Creep In An Alloy 617 Pressure Vessel Using Uniaxial Bar Test Data, Justin Allen, Allyssa Bateman, Yudhishthir Bhetwal, Theodora Caldwell, Joseph Croteau, Elias Lindau

College of Engineering Poster Presentations

Alloy 617 is being investigated as a candidate for application in next generation nuclear plants (NGNPs), including the very high temperature reactor (VHTR). Creep deformation concerns the lifetime and failure of heat exchangers used at the very high operating temperatures and pressures of such plants. In order to meet the American Society of Mechanical Engineers’ Boiler and Pressure Vessel code (ASME B&PV), and be certified for use in NGNPs, a thorough understanding of creep must be demonstrated. Current methods of testing creep have limitations and there remains uncertainty and controversy as to the applicability of these tests to more complex …

Use Of Global Electrochemical Techniques To Characterize Localized Corrosion Behavior On Aluminum Alloys, Joe Croteau, Kerry N. Allahar, Darryl P. Butt, Michael F. Hurley

College of Engineering Poster Presentations

Precipitated intermetallic phases strengthen aluminum aircraft alloys; these inclusions also establish localized electrochemical environments, significantly influencing the bulk corrosion behavior of such alloys. To gain insight on the effects of intermetallic phases on the bulk corrosion behavior, two established forms of electrochemical characterization techniques were used, polarization scans and impedance spectroscopy. This effort was undertaken to:

• Provide a statistical body of electrochemical data for aluminum alloys,
• Provide fundamental electrochemical parameters to aide in a continuum scale modeling effort,
• Validate the effect of solution chemistry on bulk corrosion behavior,
• Determine the influence of precipitated intermetallic phases on the bulk corrosion behavior, …

Compositional Tuning Of Structural Stability Of Lithiated Cubic Titania Via A Vacancy-Filling Mechanism Under High Pressure, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Experimental and theoretical studies on the compositional dependence of stability and compressibility in lithiated cubic titania are presented. The crystalline-to-amorphous phase transition pressure increases monotonically with Li concentration (from ∼17.5  GPa for delithiated to no phase transition for fully lithiated cubic titania up to 60 GPa). The associated enhancement in structural stability is postulated to arise from a vacancy filling mechanism in which an applied pressure drives interstitial Li ions to vacancy sites in the oxide interior. The results are of significance for understanding mechanisms of structural response of metal oxide electrode materials at high pressures as well as emerging …

Recrystallization Kinetics Of 3c Silicon Carbide Implanted With 400 Kev Cesium Ions, Daniel Denell Osterberg

Boise State University Theses and Dissertations

Polycrystalline 3C silicon carbide was implanted at room temperature with 400 keV cesium ions to a dose of 10¹⁶ ions·cm^-2. The samples were then annealed at 600 – 1000°C for 0-48 hours in ultra-high purity argon. The implanted zone of each sample was characterized by transmission electron microscopy and secondary ion mass spectroscopy. It is shown that the implantation resulted in a 217 ± 2 nm amorphous region with microstructural damage extending to approximately 250 nm below the surface. Recrystallization of the amorphous region was observed at 725°C, although minimal densification was observed until ≥ 800°C. Densification …

Kinetics And Mechanisms Of Titanium Wire Oxidation, Tanmay P. Engineer

Boise State University Theses and Dissertations

The kinetics and mechanisms of oxidation of titanium wire were assessed using a large test matrix in Ar-20% O₂ at 800 to 1200°C, and N₂-20% O₂ at 1000°C, for 0.5 to 24 hours. The effects of geometry on oxidation were evaluated by investigating the behavior of six high purity Ti wires with diameters varying from 50 to 2000 μm, with an objective of producing hollow TiO₂ tubes.

Oxidation behavior was characterized by measuring oxide thicknesses and morphology by optical microscopy, and the phases were characterized using a combination of SEM and TEM. The kinetics was …

Small Specimen Test Techniques For Evaluating Radiation-Induced Changes In Mechanical Properties, Ellen Marie Rabenberg

Boise State University Theses and Dissertations

The mechanical properties of as-received and irradiated 304 stainless steel (304SS) were evaluated by the shear punch and miniature tensile techniques. A purpose of this study was to evaluate the shear punch technique itself, which is a less developed technique versus miniature tensile testing. This was accomplished in part by comparing yield and ultimate strengths obtained from shear punch and miniature tensile data. The tests were further correlated by evaluating the mechanical properties of aluminum 6061 and Inconels 600 and 718. A linear relationship was observed between the shear strength and tensile strength data, providing a correlation between the two …

Fabrication Of Solid Solution Tungsten-Rhenium Alloys By High Energy Ball Milling And Spark Plasma Sintering, Cory C. Sparks

Boise State University Theses and Dissertations

Tungsten-rhenium powders of varying compositions were fabricated by spark plasma sintering (SPS). In initial exploration of the parameter space, W-25 at% Re powders were blended and consolidated by SPS at 1500 to 1900°C with sintering dwell times of 0 to 60 minutes. In addition, the influence of milling was investigated. W-25 at% Re powders were high-energy ball milled at 200 to 400 rpm for 5 hours and consolidated at 1700°C with sintering dwell times of 0 to 60 minutes. The sample densities, grain sizes, porosities, contamination level, and hardness values were measured. The intermetallic content, specifically the fraction of σ-phase, …

Structural And Electronic Properties Of Cs-Doped Sic: A First-Principles Investigation, Tram Bui

Boise State University Theses and Dissertations

The structural and electronic properties of pure and Cs-doped cubic zinc-blende silicon carbide (3C-SiC) were modeled by density functional theory in the plane-wave pseudo-potential formalism as implemented in the Quantum-ESPRESSO package. The equilibrium properties including lattice constant, bulk modulus, cohesive energy, and the indirect band gap energy were calculated for pure 3C-SiC. These values were compared with the experimental and theoretical values reported in the literature, and there was generally excellent agreement.

The influence of Cs on SiC in two structural configurations were modeled, including bulk SiC and a Σ3 grain boundary. The present investigation mainly focused on the neutral …

Effect Of Fluxing Additive On Sintering Temperature, Microstructure And Properties Of Batio3, Yaseen Iqbal, Asad Jamal, Riaz Ullah, M. Naeem Khan, Rick Ubic

Materials Science and Engineering Faculty Publications and Presentations

Various fluxing materials are added to technical ceramics in an attempt to lower their sintering temperatures and make their processing economical. The effect of 0·3wt% Li₂CO₃ addition on the phase, microstructure, phase transition temperatures and dielectric properties of BaTiO₃ was investigated in the present study. The addition of 0·3wt% Li2CO₃ was observed to lower the optimum sintering temperature by ∼200^◦C with no second phase formation and cause a five-fold reduction in grain size. Rhombohedral-to-orthorhombic and tetragonal-to-cubic phase transitions at the expected temperatures were evident from the Raman spectra, but the orthorhombic-totetragonal phase transition …

Structural Dna Origami: Engineering Supermolecular Self-Assembly For Nanodevice Fabrication, Craig Marshal Onodera

Boise State University Theses and Dissertations

Two challenges encountered in nanotechnology are the ability to create nanostructures inexpensively and the ability to arrange nanomaterials with a precision commensurate with their size. In nature, nanostructures are created using a bottom-up approach, whereby molecules hierarchically self-assemble into larger systems. Similarly, structural DNA nanotechnology harnesses the programmability, specificity, and structural integrity of DNA to engineer synthetic, self-assembled materials. For example, during scaffolded DNA origami, a long single stranded DNA polymer is artificially folded into nanostructures using short oligonucleotides. Once folded, two- and three-dimensional nanostructures may be decorated with proteins, metallic nanoparticles, and semiconductor quantum dots. Using gold nanoparticles and …

Repairing Mixed-Conducting, Ceramic Electrolyte Films, Kevin Tolman, Izaak Williamson, Kokfoong Chan

College of Engineering Poster Presentations

Ceramatec, Inc. develops ceramic-electrolyte thin films for gas separation/purification technologies. Specific ions (e.g., oxygen) can be selectively diffused through these films in order to obtain a desired product, such as syngas or pure O2. During production, residual stresses develop within the films which induce defects, such as pinholes, micro-cracks, and other sources of leaks, that allow gas contamination. To improve large-scale film production yield, four application techniques were analyzed for their feasibility of restoring the integrity of the films. Controlled, uniform defects were introduced to the films using a microindenter to enable an effective comparison of application techniques …

Particle Size Characterization Of Ferritic Oxide Dispersion Strengthened Alloy Powders, Sumit R. Tamrakar

College of Engineering Poster Presentations

Ferritic oxide dispersion strengthened (ODS) alloys are candidate materials for use in extreme applications due to their excellent high temperature strength. Fe₈₁Cr₁₆Mo₃ and Fe₈₁Cr₁₆Al₃ alloys were ball milled for various durations with 0.5 wt. % Y₂O₃ nanometer sized particles prior to consolidation via spark plasma sintering (SPS). The particle size characterization was completed using optical microscopy, scanning electron microscopy (SEM), and laser scattering. The median particle size of Fe₈₁Cr₁₆Mo₃₊0.5 wt. % Y₂O₃ powder increased from 9µm to 31µm …

Versatile In-Situ Engine Lubricant Health Sensor, Sanjeev Acharya

College of Engineering Poster Presentations

Lubricants which are used in engines to reduce friction, promote engine cooling, and prevent corrosion degrade with time under harsh engine operating conditions and hence need to be changed periodically. Since degradation of oil is a result of number of mechanisms such as; engine component wear, oil oxidation, water ingress, and carbon particles, a versatile and microscopic in-situ sensor that can sense quality of wide variety of engine lubricant brands at various temperatures and pressures is of great need. This problem can be resolved by applying portable interdigitated micro-sensors to examine the impedance behavior of degraded lubricants through electrochemical tests. …

Microstructural Characterization Of Next Generation Nuclear Graphites, Chinnathambi Karthik, Joshua Kane, Darryl P. Butt, William E. Windes, Rick Ubic

Materials Science and Engineering Faculty Publications and Presentations

This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch …

Effects Of Grain Boundary Character On Dynamic Recrystallization Using A Modified Monte Carlo Method, Michael B. Morse

Boise State University Theses and Dissertations

Dynamic recrystallization (DRX) is the recrystallization that occurs during high temperature deformation of metals and alloys. While DRX has been observed experimentally, the parameters that affect the microstructure are still being explored. For example, the effects of temperature, strain rate, and initial grain size have already been studied, yet the effect of initial special boundary fraction is still unknown. Special boundaries are high-angle, low-energy grain boundaries. It is believed that higher initial fractions of special boundaries will lead to a delay in the onset of recrystallization and a higher peak stress.

Experimentation has shown that triple junctions are preferred nucleation …

Spark Plasma Sintering Of Tungsten And Tungsten-Ceria: Microstructures And Kinetics, Jeffrey Bryce Perkins

Boise State University Theses and Dissertations

Tungsten casting is impractical, and tungsten compacts are most often produced by press-and-sinter or by hot pressing. The temperatures typically required to sinter tungsten above 90% dense are above 1800 ºC, and sintering times are typically hours. Alternatively, spark plasma sintering (SPS) can be used to consolidate materials to high densities at lower temperatures and shorter times than traditional sintering techniques. In this study, pure tungsten and tungsten with 1, 4, 10, 15, and 20 weight percent ceria were spark plasma sintered at varying pressures, temperatures, and times to investigate the microstructures and the kinetics of sintering.

Densification of tungsten …

Magnetic Field Induced Strain In Polycrystalline Magnetic Shape Memory Foam, Cassie Lynne Witherspoon

Boise State University Theses and Dissertations

Magnetic shape memory alloys (MSMA) are fascinating materials that show a recoverable shape change in a rotating magnetic field. Single crystalline MSMA’s display magnetic-field-induced strains (MFIS) up to 10%. However, single crystals have inherent drawbacks such as cost and chemical segregation during production. Polycrystalline materials are easier to produce and display chemical homogeneity but display a much smaller MFIS than single crystals. It has been shown recently that adding porosity to polycrystalline Ni-Mn-Ga (i.e. metal foam) can increase MFIS.

Variables that affect the performance of polycrystalline Ni-Mn-Ga foam include phase transformation temperature, pore architecture, spatial distribution of pores, porosity, training, …

Growth Of Oriented Nickel-Manganese-Gallium Single Crystals Via The Bridgman Method, Douglas Leroy Kellis

Boise State University Theses and Dissertations

A Bridgman furnace was designed and built to grow oriented single crystals of nickel-manganese-gallium. The starting alloys were produced from high purity elements. The compositions of the alloys and single crystals were determined with energy dispersive x-ray spectroscopy. Oxygen concentration of the starting elements, the alloys, and single crystal were determined with the LECO combustion method. Starting seeds were produced from single crystal ingots produced at ETH Zurich, Switzerland, and from a single crystal grown from these seeds. Crystallographic orientation of the starting seeds and the single crystals were determined with x-ray diffraction. Mechanical testing was performed on a single …

Minimization Of Surface Impurities In Anodized Aluminum, Logan Ward, Steven Livers, Amber Huddleston

College of Engineering Poster Presentations

Anodized aluminum is commonly used to create wear-resistant parts for process tools used in the semiconductor industry. Sinc microchips require high purity manufacturing environments[1], surface impurities on tooling needs to be minimized.

It has been determined that anodized aluminum parts are one source of contamination. This project investigates the source of trace elements in anodized aluminum 6061 parts and ways to reduce them.