Materials Science and Engineering Commons^™

Simulation Of Cooling Rate Effects On Ti-48al-2cr-2nb Crack Formation In Direct Laser Deposition, Lei Yan, Wei Li, Xueyang Chen, Yunlu Zhang, Joseph William Newkirk, Frank W. Liou, David Dietrich

Materials Science and Engineering Faculty Research & Creative Works

Transient temperature history is vital in direct laser deposition (DLD) because it reveals the cooling rate at specific temperatures, which directly relates to phase transformation and types of microstructure formed in deposit. FEA simulation was employed to study the transient temperature history and cooling rate at different experimental setups in Ti-48Al-2Cr-2Nb DLD process. In this paper, an innovative model was described, which combines a moving Gaussian distribution heat source and element birth and death technology in ANSYS, help to analysis cooling rate control method and guide crack-free deposits build process.

Modeling And Experimental Investigation Of Pre-Mixed Multi-Powder Flow In Fabricating Functional Gradient Material By Laser Metal Deposition Process, Wei Li, Jingwei Zhang, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, W. L. Seufzer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal Deposition (LMD) is an effective process to fabricate Functionally Graded Material (FGM) from pre-mixed powders. Since the supplied multi-powder directly affects the deposited FGM’s composition, investigation on Pre-Mixed Multi-Powder (PMMP) flow during LMD is greatly needed. This paper presents a comprehensive numerical PMMP flow model. By solving discrete particle force balance equations coupled with continuity equations and momentum equations for carrier gas, the dynamic behavior of PMMP flow through powder feeder tube and out of nozzle was calculated. With this model, the particle sizes of multi-powder were optimized to obtain considered FGM composition. To verify the modeling results, …

Elevated Temperature Microstructure Stability Of Slm 304l Stainless Steel, Tarak Amine, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

With time at temperature, changes in metallurgical structure can be expected for almost any steel or alloy. In stainless steels, the changes can be grain growth, carbide precipitation, ferrite decomposition, or embrittlement. These phenomena can significantly effect the properties of the steel and would potentially change the functionality of the component. Therefore, to determine component stability, the elevated temperature microstructure stability of additive manufacturing materials was studied. This work investigates the influence of different aging times of additive material stainless steels (304L) fabricated with the Selective Laser Melting (SLM) process on microstructure and mechanical properties. Microstructure and mechanical properties were …

Investigation Of Tensile Properties Of Bulk And Slm Fabricated 304l Stainless Steel Using Various Gage Length Specimens, Sreekar Karnati, I. Axelsen, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The complex solidification dynamics and thermal cycling during Selective Laser Melting process is expected to result in non-equilibrium material characteristics. There is an essential need for characterization techniques which are critical towards the estimation of anisotropies. The current investigation is targeted towards establishing tensile testing methodologies and their relation to differing gage lengths. Dog-bone shaped specimen designs with gage lengths of 1”, 0.3” and 0.12” were employed in this research. The characterization was performed on hot rolled-annealed 304 stainless and SLM fabricated 304L stainless. It was theorized that smaller gage length specimens would be instrumental in mapping material property anisotropy …

Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content (< 1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.

Investigation Of Heat-Affected 304l Ss Powder And Its Effect On Built Parts In Selective Laser Melting, Caitlin S. Kriewall, Austin T. Sutton, Ming-Chuan Leu, Joseph William Newkirk, Ben Brown

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective laser melting (SLM) is a powder bed based additive manufacturing process in which a layer of powder is laid over the surface of a substrate and a laser with sufficient energy is employed to selectively melt particles to build a part layer by layer. During the SLM process, dark smoke was observed coming off of the powder bed surface where the laser was interacting with powder. This phenomenon resulted from heat-affected powder that was visibly different than the base powder. Since the concentration of the heat-affected powder differs throughout the build chamber as a result of the recirculating argon …

Effect Of Powder Particle Size On The Fabrication Of Ti-6al-4v Using Laser Metal Deposition From Elemental Powder Mixture, Xueyang Chen, Lei Yan, Wei Li, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct Laser Metal Deposition (LMD) was used to fabricate thin-wall Ti-6Al-4V using the powder mixture of Ti-6 wt.%Al-4 wt.%V. Scanning electron microscopy (SEM), optical microscopy (OM) and energy dispersive spectroscopy (EDS) were employed to examine the chemical composition and microstructure of the as-deposited sections. Vickers hardness tests were then applied to characterize the mechanical properties of the deposit samples which were fabricated using pre-mixed elemental powders. The EDS line scans indicated that the chemical composition of the samples was homogenous across the deposit. X-ray diffraction (XRD) was used for the phase identification. After significant analysis, some differences were observed among …

Proposed Hybrid Processes For Part Building Using Fusion Welding And Friction Stir Processing, Megan A. Gegesky, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It has been shown that a hybrid laser additive manufacturing and friction stir processing can deposit components with forged-like structures. This paper reports a hybrid fusion welding and friction stir process to create parts with quality structures. Combining traditional fusion welding and friction stir processing techniques for non-weldable aluminum alloys could facilitate the joining of difficult geometries in manufactured parts. This research illustrates mechanical property changes for non-weldable and weldable aluminum alloys. The Vickers hardness, and microhardness in the case of AA5052-H32, tensile strength and corrosion resistance of four processing states: base material, fusion welded material, friction stir welded material, …

A Dissolution-Precipitation Mechanism Is At The Origin Of Concrete Creep In Moist Environments, Isabella Pignatelli, Aditya Kumar, R. Alizadeh, Yann Le Pape, Mathieu Bauchy, Gaurav Sant

Materials Science and Engineering Faculty Research & Creative Works

Long-term creep (i.e., deformation under sustained load) is a significant material response that needs to be accounted for in concrete structural design. However, the nature and origin of concrete creep remain poorly understood and controversial. Here, we propose that concrete creep at relative humidity ≥ 50%, but fixed moisture content (i.e., basic creep), arises from a dissolution-precipitation mechanism, active at nanoscale grain contacts, as has been extensively observed in a geological context, e.g., when rocks are exposed to sustained loads, in liquid-bearing environments. Based on micro-indentation and vertical scanning interferometry data and molecular dynamics simulations carried out on calcium-silicate-hydrate (C-S-H), …

Preface To The Special Issue On Advanced Microstructural Characterization Of Materials, Haiming Wen

Materials Science and Engineering Faculty Research & Creative Works

Microstructural characterization is a vital part in materials science, as it plays a key role in understanding the structure-property relationship in materials. Various advanced microstructural characterization techniques have emerged, for example, scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, high resolution (scanning) transmission electron microscopy, electron backscatter diffraction, energy dispersive x-ray spectroscopy, electron energy loss spectroscopy, precession electron diffraction, energy-filtered transmission electron microscopy, and atom probe tomography. The applications of these techniques have greatly advanced the understanding of material microstructures on different scales from micrometer to atomic scale. Advanced microstructural characterization can be applied to a variety of …

Stability Of The M2 Phase Of Vanadium Dioxide Induced By Coherent Epitaxial Strain, N. F. Quackenbush, Yijia Gu, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

Tensile strain along the cR axis in epitaxial VO₂ films raises the temperature of the metal insulator transition and is expected to stabilize the intermediate monoclinic M2 phase. We employ surface-sensitive x-ray spectroscopy to distinguish from the TiO₂ substrate and identify the phases of VO₂ as a function of temperature in epitaxial VO₂/TiO₂ thin films with well-defined biaxial strain. Although qualitatively similar to our Landau-Ginzburg theory predicted phase diagrams, the M2 phase is stabilized by nearly an order of magnitude more strain than expected for the measured temperature window. Our results reveal that the …

Coupling Between Magnetic Exchange And Charge Activation In Cu-Doped Lafeo3, Emir Dogdibegovic, Qingsheng Cai, William Joseph James, William B. Yelon, Harlan U. Anderson, Jin Bo Yang, Xiao Dong Zhou

Chemistry Faculty Research & Creative Works

Material research on perovskite-type oxides (ABO₃) has been driven by the recognition of their unique properties primarily attributed to the presence of oxygen octahedron (BO₆). Since 2003, the discovery of strong coupling in TbMnO₃ and BiFeO₃ has stimulated new interests in understanding the relationship between magnetic and electric properties in perovskites. In this article, we report our recent work on the magnetic superexchange interaction and charge formation in copper-doped LaFeO₃ using high-temperature neutron diffraction and thermoelectric measurements. In situ neutron diffraction measurements show a loss of antiferromagnetic ordering above 450°C. With an increase …

Effect Of The Inherent Eccentricity In Single-Lap Direct-Shear Tests Of Pbo Frcm-Concrete Joints, Tommaso D'Antino, Lesley Sneed, Christian Carloni, Carlo Pellegrino

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Investigation of the bond between fiber reinforced composites and the substrates onto which they are applied is of critical importance to understand their failure mechanisms. The bond behavior can be studied using different experimental test set-ups; the most commonly used are the single-lap and double-lap direct-shear tests. Although single-lap shear tests are simpler to carry out than double-lap shear tests, the presence of an eccentricity between the pulling and restraining forces leads to a mixed mode fracture process at the interface, which may influence the results. This study investigates the eccentricity effect on the bond behavior of fiber reinforced cementitious …

Management Of A Sever Degloving Foot Injury: A Rare Presentation Of Food Injury In Emergency Department, Ugur Lok, Hasan Buyukaslan, Umut Gulacti, Fatih Dogan, Irfan Aydin

Materials Science and Engineering Faculty Research & Creative Works

Occupational crash injuries of the foot present a significant reconstructive challenge due to the superficial location of structures such as tendon, joint and neurovascular network essential for proper acceptance of weight bearing and shear forces associated with bipedal gait. We discussed here a rare case in which an extensive degloving injury of the foot and combined with knee traumatic dislocation and proximal fibula tip fracture that underwent amputation. The authors suggested that none of treatment modalities of degloving are entirely satisfactory, so that each case must be considered independently with cons and pros

The Anisotropy Of Hexagonal Close-Packed And Liquid Interface Free Energy Using Molecular Dynamics Simulations Based On Modified Embedded-Atom Method, Ebrahim Asadi, Mohsen Asle Zaeem

Materials Science and Engineering Faculty Research & Creative Works

This work aims to comprehensively study the anisotropy of the hexagonal close-packed (HCP)-liquid interface free energy using molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM). As a case study, all the simulations are performed for Magnesium (Mg). The solid-liquid coexisting approach is used to accurately calculate the melting point and melting properties. Then, the capillary fluctuation method (CFM) is used to determine the HCP-liquid interface free energy (γ) and anisotropy parameters. In CFM, a continuous order parameter is employed to accurately locate the HCP-liquid interface location, and the HCP symmetry-adapted spherical harmonics are used to expand γ …

Post-Repair Seismic Assessment Of Rc Bridges Damaged With Fractured Column Bars - A Numerical Approach, Ruili He, Yang Yang, Lesley H. Sneed

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Seismic repair of reinforced concrete (RC) bridge columns has been studied extensively during the past several decades; however, few studies have been conducted on the influence of the column repair (member level) on the post-repair performance of bridge structures (system level). In a previous experimental study by the authors, a method was developed to rapidly repair severely damaged RC bridge columns to enable the quick reopening of the bridge to emergency traffic. Thus, a lower limit state was used for the repair design, so that the lateral strength and drift capacity of a repaired RC column with fractured longitudinal bars …

Ceramic-Ceramic Welds, Greg Hilmas, William Fahrenholtz, Jeremy Lee Watts, Derek Scott King, Sean Landwehr

Materials Science and Engineering Faculty Research & Creative Works

A method of producing a ceramic weld, including identifying a ceramic first surface an a ceramic second surface to he bonded together, maintaining a non-oxidizing atmosphere over the first and second surfaces, and engaging the first and second surfaces to define a joint, An arc is generated between an electrode and the joint to create a liquid phase, and the liquid phase is cooled to yield a solid fusion layer, wherein the first and second surfaces are joined in the fusion layer.

Glass Derived Nanoparticles For Nerve Tissue Repair, D. E. Day, Ali Mohammadkah, Amy Beth Harkins, Laura Marquardt

Materials Science and Engineering Faculty Research & Creative Works

A biocompatible, biodegradable composite material, and method of using nanoparticles formed within the composite material for nerve repair are disclosed. The nanoparticles may not be formed until the glass degrades upon contact with a fluid in vivo or in vitro.

Erratum: "Composition- And Pressure-Induced Ferroelectric To Antiferroelectric Phase Transitions In Sm-Doped Bifeo₃ System" [Appl. Phys. Lett. 106, 012903 (2015)], Fei Xue, Linyun Liang, Yijia Gu, Ichiro Takeuchi, Sergei V. Kalinin, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

In the acknowledgement of the original article, the Award No. DMR-0820404 should be replaced by DMR-1420620.

Erratum: Orientations Of Low-Energy Domain Walls In Perovskites With Oxygen Octahedral Tilts (Physical Review B - Condensed Matter And Materials Physics (2014) 90 (220101)), Fei Xue, Yijia Gu, Linyun Liang, Yi Wang, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

In the Acknowledgment of the original article, the Award No. DMR-0820404 should be replaced by DMR-1420620.

Microwave Material Characterization Of Alkali-Silica Reaction (Asr) Gel In Cementitious Materials, Ashkan Hashemi

Doctoral Dissertations

"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive …

Synthesis And Functionalization Of A Triaryldiamine-Base Photoconductive/Photorefractive Composite, And Its Application To Aberrated Image Restoration, Yichen Liang

Doctoral Dissertations

"Organic photorefractive (PR) composites have recently emerged as an important class of materials for applications including high-density data storage, optical communication, and biomedical imaging. In an effort to further improve their performance, this study focused on the utilization of functionalized semiconductor nanocrystals to photosensitize triaryamine (TPD)-based PR composites, as well as the application of TPD-based PR composites in the restoration of aberrated optical information. A novel approach to functionalize CdSe quantum dot (QCdSe) was firstly introduced where the sulfonated triarydiamine (STPD) was used as charge-transporting ligand to passivate QCdSe. TPD-based photoconductive and PR composites were photosensitized with the STPD-passivated QCdSe …

On The Spheroidal Graphite Growth And The Austenite Solidification In Ductile Irons, Jingjing Qing

Doctoral Dissertations

"Evolutions of austenite and nodular/spheroidal graphite particles during solidifications of ductile irons were experimentally investigated. Spheroidal graphite particle and austenite dendrite were found nucleated independently in liquid. Austenite dendrite engulfed the spheroidal graphite particles after contact and an austenite shell formed around a spheroidal graphite particle. The graphite diameter at which the austenite shell closed around nodule was determined. Statistically determined graphite size distributions indicated multiple graphite nucleation events during solidification.

Structures in a graphite nodule varied depending on the growth stages of the nodule in ductile iron. Curved graphene layers appearing as faceted growth ledges swept circumferentially around the …

Dft Investigations Of Hydrogen Storage Materials, Gang Wang

Doctoral Dissertations

"Hydrogen serves as a promising new energy source having no pollution and abundant on earth. However the most difficult problem of applying hydrogen is to store it effectively and safely, which is smartly resolved by attempting to keep hydrogen in some metal hydrides to reach a high hydrogen density in a safe way. There are several promising metal hydrides, the thermodynamic and chemical properties of which are to be investigated in this dissertation.

Sodium alanate (NaAlH₄) is one of the promising metal hydrides with high hydrogen storage capacity around 7.4 wt. % and relatively low decomposition temperature of …

Multiphase Field Modeling Of The Formation Path Of Delta Hydrides In Zirconium, Jacob Luke Bair

Doctoral Dissertations

"Zirconium alloys are commonly used in nuclear fuel rod claddings due to their high ductility, good corrosion resistance, and low neutron absorption cross section. Among the most important weaknesses of zirconium alloys is their affinity for hydrogen, resulting in formation of hydrides in the cladding, and leading to embrittlement and mechanical failure. Despite numerous studies on hydride precipitation in zirconium alloys, the nucleation and formation path of stable δ hydrides in α zirconium matrix are not yet fully understood.

In this Ph.D. research project, two novel quantitative phase-field models were developed and utilized to advance our understanding of mechanisms of …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Coupled Crystal Orientation-Size Effects On The Strength Of Nano Crystals, Rui Yuan, Irene J. Beyerlein, Caizhi Zhou

Materials Science and Engineering Faculty Research & Creative Works

We study the combined effects of grain size and texture on the strength of nanocrystalline copper (Cu) and nickel (Ni) using a crystal-plasticity based mechanics model. Within the model, slip occurs in discrete slip events exclusively by individual dislocations emitted statistically from the grain boundaries. We show that a Hall-Petch relationship emerges in both initially texture and non-textured materials and our values are in agreement with experimental measurements from numerous studies. We find that the Hall-Petch slope increases with texture strength, indicating that preferred orientations intensify the enhancements in strength that accompany grain size reductions. These findings reveal that texture …

Refractive Index And Thermo-Optic Coefficients Of Ge-As-Se Chalcogenide Glasses, Benn Gleason, Kathleen Richardson, Laura Sisken, Charmayne Smith (Lonergan)

Materials Science and Engineering Faculty Research & Creative Works

Seventeen glasses in the Ge-As-Se ternary glass-forming region have been fabricated and analyzed to provide input for optical design data and to establish composition- and structure-based relationships to aide development of novel chalcogenide glasses with tailored optical functionality. While known that Ge addition to binary As-Se glasses enhances the mean coordination number (MCN) of the network and results in increased Tg and decreased CTE, this work highlights the impact on optical properties, specifically mid-wave (λ = 4.515 μm) index and thermo-optic coefficient (dn/dT). Trends in property changes were correlated with an excess or deficiency of chalcogen content in the glassy …

Synthesis And Photonic Sintering Of Bioresorbable Zinc Nanoparticle Ink For Transient Electronics Manufacturing, Bikram K. Mahajan

Masters Theses

"Zinc is an essential 'trace element' that supports immune systems, and is required for DNA synthesis, cell division, and protein synthesis. Zinc nanoparticles (Zn NP) has antibacterial properties and potential to be used in biodegradable printed electronics devices. The research presented here is about the synthesis of Zn NP and their potential use in transient electronics devices. In Paper 1, a technique of room temperature synthesis of Zn NP is reported using ball milling. Controlled amount of PVP was mixed in the solvent to stabilize the Zn particles and minimize cold welding during milling. The size of the produced Zn …

Biodegradable Electronic And Optical Devices Toward Temporary Implants, Md Shihab Adnan

Masters Theses

"Implantable biomedical devices have a high potential to revolutionize health care technologies in near future. Implantable devices can be classified as permanent prosthetic devices such as pacemakers or nerve stimulants and temporary devices for intermediate monitoring and control scenario which are still in research phase. In contrast to permanent device, temporary implants lose functionality and become unnecessary after intended operational lifetime which may pose serious electromagnetic and biomedical safety concern, latent complications at the implanted sites and possible ethical issues if not removed from body by an additional surgical operation.

The first paper of this thesis focuses on exploring the …