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Integration, Stability, and Doping of Mono-Elemental and Binary Transition Metal Dichalcogenide Van der Waals Solids for Electronics and Sensing Devices

Description: In this work, we have explored 2D semiconducting transition metal dichalcogenides (TMDs), black phosphorus (BP), and graphene for various applications using liquid and mechanical exfoliation routes. The topical areas of interest that motivate our work include considering factors such as device integration, stability, doping, and the effect of gasses to modulate the electronic transport characteristics of the underlying 2D materials. In the first area, we have integrated solution-processed trans… more
This item is restricted from view until June 1, 2024.
Date: May 2022
Creator: Mehta, Ravindra K
Item Type: Refine your search to only Thesis or Dissertation
open access

Mechanically Driven Reconstruction of Materials at Sliding Interfaces to Control Wear

Description: To minimize global carbon emissions, having efficient jet engines and internal combustion engines necessitates utilizing lightweight alloys such as Al, Ti, and Mg-based alloys. Because of their remarkable strength/weight ratio, these alloys have received a lot of attention. Nonetheless, they have very poor tribological behavior, particularly at elevated temperatures beyond 200 °C, when most liquid lubricants begin to fail in lubrication. Over the last two decades, there has been a lot of intere… more
Date: May 2022
Creator: Shirani, Asghar
Item Type: Refine your search to only Thesis or Dissertation

Time-Dependent Deformation Mechanisms in Metallic Glasses as a Function of Their Structural State

Description: In this study, the time-dependent deformation behavior of several model bulk metallic glasses (BMGs) was studied. The BMGs were obtained in different structural states by thermal relaxation below their glass transition temperature, cryogenic thermal cycling, and chemical rejuvenation by micro-alloying. The creep behavior of Zr52.5Ti5Cu17.9Ni14.6Al10 BMG in different structural states was investigated as a function of peak load and temperature. The creep strain rate sensitivity (SRS) indicated a… more
This item is restricted from view until June 1, 2024.
Date: May 2022
Creator: Ghodki, Nandita
Item Type: Refine your search to only Thesis or Dissertation

Tuning of Microstructure and Mechanical Properties in Additively Manufactured Metastable Beta Titanium Alloys

Description: The results from this study, on a few commercial and model metastable beta titanium alloys, indicate that the growth restriction factor (GRF) model fails to interpret the grain growth behavior in the additively manufactured alloys. In lieu of this, an approach based on the classical nucleation theory of solidification incorporating the freezing range has been proposed for the first time to rationalize the experimental observations. Beta titanium alloys with a larger solidification range (liquid… more
This item is restricted from view until June 1, 2024.
Date: May 2022
Creator: Nartu, Mohan Sai Kiran Kumar Yadav
Item Type: Refine your search to only Thesis or Dissertation

Wear, Friction and High Shear Strain Deformation of Metallic Glasses

Description: In this work, wear and scratch behavior of four different bulk metallic glasses (BMGs) namely Zr41.2Cu12.5Ni10Ti13.8Be22.5 (LM 1), Zr57Cu15.4Ni12.6Al10Nb5 (LM 106), Ni60Pd20P17B3 (Ni-BMG), and Pt57.5Cu14.7Ni5.3P22.5 (Pt-BMG) were compared. Shear band formation on the edges of the scratch groove with spallation was found to be the primary failure mechanism in progressive scratch tests. The wear behavior and the scratch response of model binary Ni-P metallic glasses was systematically studied as … more
This item is restricted from view until June 1, 2024.
Date: May 2022
Creator: Pole, Mayur
Item Type: Refine your search to only Thesis or Dissertation
open access

Additive Manufacturing of AZ31B Magnesium Alloy via Friction Stir Deposition

Description: Additive friction stir deposition (AFSD) of AZ31B magnesium alloy was conducted to examine evolution of grain structure, phases, and crystallographic texture. AFSD was carried out using a hollow tool made from tool steel at a constant rotational velocity of 400 rpm on the AZ31B base plate. Bar stock of AZ31B was utilized as a feed material. The linear velocity of the tool was varied in the range of 4.2-6.3 mm/s. The feed rate of the material had to be maintained at a half value compared to the … more
Date: December 2021
Creator: Patil, Shreyash Manojkumar
Item Type: Refine your search to only Thesis or Dissertation

Advanced Cathodes for High Energy Density Lithium Sulfur Battery

Description: A systematic development of 2D alloy catalyst with synergistic performance of high lithium polysulfide (LiPS) binding energy and efficient Li+ ion/electron conduction is presented. The first section of work found that Li+ ions can flow through the percolated ion transport pathway in polycrystalline MoS2, while Na+ and K+ ions can easily flow through the percolated 1D ion channel near the grain boundaries. An unusually high ionic conductivity of extrinsic Li+, Na+, and K+ ions in 2D MoS2 film ex… more
Date: December 2021
Creator: Bhoyate, Sanket
Item Type: Refine your search to only Thesis or Dissertation

First Principles Study of the Effect of Local Bonding on Diffusion Mechanisms in Alloys

Description: This work demonstrates how local, randomized tailoring of bond stiffness can affect the activation energy of diffusion in model alloys using density functional theory-based computations. This work is organized into two parts. The first part deals with the vacancy diffusion mechanism, and it compares the in–plane (IP) vs out-of-plane (OOP) diffusion paths in prototypical binary Mg-X (Ca, Y, and Gd) and ternary Mg-X (Ca, Y, and Gd)-Zn alloys. We examine how vacancy formation, migration, and solut… more
Date: December 2021
Creator: Paranjape, Priyanvada Madhukar
Item Type: Refine your search to only Thesis or Dissertation
open access

Fractography and Mechanical Properties of Laminated Alumina and Yttria Stabilized Zirconia

Description: Yttria stabilized zirconia (YSZ) is a polymorph with possible phase transformation toughening occurring during impact. The fractography and mechanical properties of laminated alumina and YSZ were studied in this thesis. Five sample types were studied in this thesis: (5:5) Al2O3/YSZ (a sequence of 5 alumina tapes stacked on 5 YSZ tapes), (5:5) Al2O3/YSZ (1 wt.% Pure ZrO2), (7:3) Al2O3/YSZ, Al2O3, and YSZ. Scanning electron microscopy (SEM) and X-ray microscopy (XRM) were used to study morphology… more
Date: December 2021
Creator: Cotton, Shomari Johnny
Item Type: Refine your search to only Thesis or Dissertation
open access

Structural and Magnetic Properties of Additively Manufactured Hiperco (FeCo-2V)

Description: The FeCo-V alloy, commercially referred to as Hiperco, is known for its great soft magnetic properties. However, the high cost of production has limited the usage of this alloy to small-scale applications, where the small volume and high magnetic performance are critical. Additive manufacturing (AM) has the potential to solve the production problems that exist in Hiperco manufacturing. The present research has focused on selective laser melting (SLM) based AM processing of Hiperco. The goal was… more
Date: December 2021
Creator: O'Donnell, Aidan James
Item Type: Refine your search to only Thesis or Dissertation
open access

Thermokinetics-Dependent Microstructural Evolution and Material Response in Laser-Based Additive Manufacturing

Description: Laser-based additive manufacturing offers a high degree of thermokinetic flexibility that has implications on the structure and properties of the fabricated component. However, to exploit the flexibility of this process, it is imperative to understand the process-inherent thermokinetic evolution and its effect on the material characteristics. In view of this, the present work establishes a fundamental understanding of the spatiotemporal variation of thermokinetics during the fabrication of the … more
Date: December 2021
Creator: Pantawane, Mangesh V
Item Type: Refine your search to only Thesis or Dissertation
open access

Unraveling the Effect of Atomic Configurations and Structural Statistics on Mechanical Behavior of Multicomponent and Amorphous Alloys

Description: Multicomponent high-entropy and amorphous alloys represent relatively new classes of structural materials with complex atomic configurations and exceptional mechanical properties. However, there are several knowledge gaps in the relationships between their atomic structure and mechanical properties. Understanding these critical relationships will enable novel alloy design and tailoring of their mechanical properties for desired engineering applications. In this dissertation, first-principles ca… more
Date: December 2021
Creator: Yang, Yu Chia
Item Type: Refine your search to only Thesis or Dissertation

Self-Healing Ceramics for High Temperature Application

Description: Ceramics have a wide variety of applications due to their unique properties; however, the low fracture toughness leads the formation and propagation of unpredictable cracks, and reduces their reliability. To solve this problem, self-healing adaptive oxides were developed. The aim of the work is to gain new insights into self-healing mechanisms of ceramics and their application. Binary oxide systems were investigated that are at least partially healed through the extrinsic or intrinsic addition … more
Date: August 2021
Creator: Gu, Jingjing
Item Type: Refine your search to only Thesis or Dissertation

Synergistic Effects of Lattice Instability and Chemical Ordering on FCC Based Complex Concentrated Alloys

Description: The current work investigates how the interactions among constituent elements in high entropy alloys or complex concentrated alloys (HEA/CCAs) can lead to lattice instability and local chemical ordering which in turn affects the microstructure and properties of these alloys. Using binary enthalpies of mixing, the degree of ordering in concentrated multi-component solid solutions was successfully tailored by introducing Cr, Al and Ti in a CoFeNi HEA/CCA. CoFeNi was selected as the base alloy to … more
Date: August 2021
Creator: Dasari, Sriswaroop
Item Type: Refine your search to only Thesis or Dissertation

Alloy Design, Processing and Deformation Behavior of Metastable High Entropy Alloys

Description: This dissertation presents an assortment of research aimed at understanding the composition-dependence of deformation behavior and the response to thermomechanical processing, to enable efficient design and processing of low stacking fault energy (SFE) high entropy alloy (HEAs). The deformation behavior and SFE of four low SFE HEAs were predicted and experimentally verified using electron microscopy and in-situ neutron diffraction. A new approach of employing a minimization function to refine … more
Date: May 2021
Creator: Frank, Michael (Materials science researcher)
Item Type: Refine your search to only Thesis or Dissertation

Defect-Engineered Two-Dimensional Transition Metal Dichalcogenides for High-Efficient Piezoelectric Sensor

Description: Piezoelectricity in two-dimensional (2D) transition metal dichalcogenides (TMDs) has attracted significant attention due to their unique crystal structure and the lack of inversion centers when the bulk TMDs thin down to monolayer. Although the piezoelectricity effect in atomic-thickness TMDs has been demonstrated, they are not scalable. Herein, we demonstrate a piezoelectric effect from large-scale, sputtered MoS2 and WS2 using a robust defect-engineering based on the thermal-solvent annealing… more
Date: May 2021
Creator: Kim, Junyoung
Item Type: Refine your search to only Thesis or Dissertation

Effects of Surface Texture and Porosity on the Corrosion Behavior and Biocompatibility of Pure Zinc Biomaterials for Orthopedic Applications

Description: In this dissertation, small and large NaCl particle-derived surfaces (Ra > 40 microns) were generated on 2D Zn materials, and the surfaces were carefully studied concerning topography, corrosion behavior, and bone cell compatibility. Increases in surface roughness accelerated the corrosion rate, and cell viability was maintained. This method was then extended to 3D porous scaffolds prepared by a hybrid AM/casting technique. The scaffolds displayed a near-net shape, an interconnected pore struct… more
Date: May 2021
Creator: Cockerill, Irsalan
Item Type: Refine your search to only Thesis or Dissertation
open access

Engineering the Uniform Lying Helical Structure in Chiral Nematic Liquid Crystal Phase: From Morphology Transition to Dimension Control

Description: Chiral nematic liquid crystals or cholesteric liquid crystals (CLC) can be obtained by adding a chiral dopant into a nematic liquid crystal. Liquid crystal molecules spontaneously rotate along a long axis to form helical structures in CLC system. Both pitch size and orientation of the helical structure is determined by the boundary conditions and can be further tuned by external stimuli. Particularly, the uniform lying helical structure of CLC has attracted intensive attention due to its beam s… more
Date: May 2021
Creator: Jia, Zhixuan
Item Type: Refine your search to only Thesis or Dissertation

High Strain Rate Deformation Behavior of Single-Phase and Multi-Phase High Entropy Alloys

Description: Fundamental understanding of high strain rate deformation behavior of materials is critical in designing new alloys for wide-ranging applications including military, automobile, spacecraft, and industrial applications. High entropy alloys, consisting of multiple elements in (near) equimolar proportions, represent a new paradigm in structural alloy design providing ample opportunity for achieving excellent performance in high strain rate applications by proper selection of constituent elements a… more
Date: May 2021
Creator: Muskeri, Saideep
Item Type: Refine your search to only Thesis or Dissertation

Investigation of Porous Ceramic Structure by Freeze-Casting

Description: The design and fabrication of porous ceramic materials with anisotropic properties has, in recent years, gained popularity due to their potential application in various areas that include medical, energy, defense, space, and aerospace. Freeze-casting is an effective, low-cost, and safe method as a wet shaping technique to create these structures. To control the morphology of these materials, many critical factors were found to play an important role. In this dissertation, the processing paramet… more
Date: May 2021
Creator: Bakkar, Said Adnan
Item Type: Refine your search to only Thesis or Dissertation

Optical Emission Spectroscopy Monitoring Method for Additively Manufactured Iron-Nickel and Other Complex Alloy Samples

Description: The method of optical emission spectroscopy has been used with Fe-Ni and other complex alloys to investigate in-situ compositional control for additive manufacturing. Although additive manufacturing of metallic alloys is an emerging technology, compositional control will be a challenge that needs to be addressed for a multitude of industries going forward for next-gen applications. This current scope of work includes analysis of ionized species generated from laser and metal powder interaction … more
Date: May 2021
Creator: Flannery, David A. (David Andrew)
Item Type: Refine your search to only Thesis or Dissertation

Origin of Unusually Large Hall-Petch Strengthening Coefficients in High Entropy Alloys

Description: High entropy alloys (HEAs), also referred to as complex concentrated alloys (CCAs), are a relatively new class of alloys that have gained significant attention since 2010 due to their unique balance of properties that include high strength, ductility and excellent corrosion resistance. HEAs are usually based on five or more elements alloyed in near equimolar concentrations, and exhibit simple microstructures by the formation of solid solution phases instead of complex compounds. HEAs have great… more
Date: May 2021
Creator: Jagetia, Abhinav
Item Type: Refine your search to only Thesis or Dissertation

Switchable and Memorable Adhesion of Gold-Coated Microspheres with Electrochemical Modulation

Description: Switchable adhesives using stimuli-responsive systems have many applications, including transfer printing, climbing robots, and gripping in pick and place processes. Among these adhesives, electroadhesive surface can spontaneously adjust their adhesion in response to an external electric field. However, electroadhesives usually need high voltage (e.g. kV) and the adhesion disappears upon turning off the signal. These limitations make them complicated and costly. In this research, we demonstrate… more
Date: May 2021
Creator: Wang, Jie (Materials scientist)
Item Type: Refine your search to only Thesis or Dissertation
open access

Processing, Pre-Aging, and Aging of NiTi-Hf (15-20 at.%) High Temperature Shape Memory Alloy from Laboratory to Industrial Scale

Description: The overarching goal of this research was to generate a menu of shape memory alloys (SMAs) actuator materials capable of meeting the demands of aerospace applications. Material requirements were recognized to meet the demand for high temperature SMAs with actuating temperatures above 85 °C and provide material options capable of performing over 100K actuation cycles. The first study is a preliminary characterization for the down selection of Ni-rich NiTiHf15 compositions chosen for a more in-de… more
Date: December 2020
Creator: Gantz, Faith
Item Type: Refine your search to only Thesis or Dissertation
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