Materials Science and Engineering Commons^™

Nano-Patterned Si Structures For Optical Filters And Electro-Mechanical Relays: Fabrication, Characterization, Prospects, And Limitations, Md Ataul Mamun

Theses and Dissertations

Nanofabrication technology, especially nanopatterning, is a rapidly advancing field that has already resulted in creating novel devices and holds promise for producing even more with unmatched performance. These techniques also allow us to gain insight into physical phenomena at the micro- and nanoscale. The ultimate performance of nanofabricated devices and their compatibility with existing Si-based CMOS technology hinge upon the careful selection of materials and precise design, coordinated with meticulous pattern transfer. In this work, we applied nanopatterning techniques on silicon to create optical filters for the shortwave infrared (SWIR) region and nanoelectromechanical system (NEMS) relay-based logic gates. Additionally, these …

Insights Into The Characterization And Degradation Of Electrospun Polycaprolactone Scaffolds For Tissue Engineering Applications, Caleb B. Wells

Theses and Dissertations

Electrospun polymeric biodegradable scaffolds are essential in tissue engineering, particularly for Engineered Tissue Vascular Grafts (ETVGs), which promise advancements in treating coronary artery disease, peripheral arterial disease, congenital cardiovascular defects, and renal disease. These scaffolds present a solution to issues with autologous graft availability and durability. While large-diameter grafts in low-pressure environments have seen success, small-diameter grafts in high-flow scenarios remain challenging. Understanding polymeric scaffold degradation and behavior during incubation, especially under dynamic mechanical loading, is vital for clinical translation of small-caliber ETVGs.

This research focuses on characterizing the mechanical and microstructural properties of electrospun polycaprolactone (PCL) scaffolds and their …

Solidification Cracking In Additively Manufactured High Entropy Alloy Nicrcofe With V Or W, Andrew R. Walch

Dissertations, Master's Theses and Master's Reports

Recent sustainability efforts have reduced CO2 emissions from electricity generation by increasing operating temperatures and pressures in advanced ultra-supercritical (A-USC) power plants. However, the extreme operating conditions in these A-USC power plants require new high temperature materials. The recent study of nickel-based high-entropy alloys (HEA) represents the latest approach to meet the specifications for A-USC operations. A CALculation PHase Diagram (CALPHAD) driven Bayesian optimization method was used to design the composition of alloys composed of NiCrCoFe with V or W, which were fabricated via wire-based additive manufacturing to enable high throughput development. Although the alloy was designed to minimize solidification …

Spinel Oxide Enables High-Temperature Self-Lubrication In Superalloys, Zhengyu Zhang, Eitan Hershkovitz, Qi An, Liping Liu, Xiaqing Wang, Zhifei Deng, Garrett Baucom, Wenbo Wang, Jing Zhao, Ziming Xin, Lowell Moore, Yingqi Yao, Md Rezwan Ul Islam, Xin Chen, Bai Cui, Ling Li, Hongliang Xin, Lin Li, Honggyu Kim, Wenjun Cai

Research, Publications & Creative Work

The ability to lubricate and resist wear at temperatures above 600 °C in an oxidative environment remains a significant challenge for metals due to their high-temperature softening, oxidation, and rapid degradation of traditional solid lubricants. Herein, we demonstrate that high-temperature lubricity can be achieved with coefficients of friction (COF) as low as 0.10-0.32 at 600- 900 °C by tailoring surface oxidation in additively-manufactured Inconel superalloy. By integrating high-temperature tribological testing, advanced materials characterization, and computations, we show that the formation of spinel-based oxide layers on superalloy promotes sustained self-lubrication due to their lower shear strength and more negative formation and …

Using Tensile And Compressive Stress Superposition During Incremental Forming To Manipulate Martensitic Transformation In Ss304, Elizabeth M. Mamros, Fabian Maaß, A. Erman Tekkaya, Brad L. Kinsey, Jinjin Ha

Faculty Conference Papers and Presentations

Single point incremental forming (SPIF) is a flexible manufacturing process that has applications in industries ranging from biomedical to automotive. In addition to rapid prototyping, which requires easy adaptations in geometry or material for design changes, control of the final part properties is desired. One strategy that can be implemented is stress superposition, which is the application of additional stresses during an existing manufacturing process. Tensile and compressive stresses applied during SPIF showed significant effects on the resulting microstructure in stainless steel 304 truncated square pyramids. Specifically, the amount of martensitic transformation was increased through stress superposed incremental forming. Finite …

High-Temperature Oxidation Behavior Of High Entropy Carbide (Tanbtiv)C In Atmospheres With Different Oxygen Contents, Ruoyu Chen, Hongbin An, Jie Zhan, Saisai Li, Aiqin Mao, Haiming Wen

Materials Science and Engineering Faculty Research & Creative Works

A high entropy carbide (TaNbTiV)C was fabricated via spark plasma sintering of high entropy powders that were prepared using a molten salt method. The as-fabricated high entropy carbide was then investigated for its high-temperature oxidation behavior at 850 °C, under atmospheres with three different oxygen contents (20 vol%, 40 vol%, and 60 vol%). After the high-temperature oxidation process, the main phases observed in all the specimens were incompletely oxidized phase (Nb_xTi_1-x)C_yO_2-y and oxides (Nb_0.5Ta_0.5)₂O₅, TiO₂, and Nb₂O₅. Importantly, the …

Synergistic Hardening In A Dual Phase High-Entropy (Hf,Nb,Ta,Ti,Zr)C–(Hf,Nb,Ta,Ti,Zr)B2 Ultra-High Temperature Ceramic, Rubia Hassan, William G. Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

A dual phase high-entropy (Hf,Nb,Ta,Ti,Zr)C–(Hf,Nb,Ta,Ti,Zr)B2 ultra-high temperature ceramic was synthesized using a single step boro-carbothermal reduction route. The synthesized powder was densified by spark plasma sintering at 2000°C, resulting in complete solid solution formation and a relative density of ≈99%. The dual phase ceramic was 43 vol% high-entropy carbide and 57 vol% high-entropy boride. The grain sizes were 0.85 ± 0.34 µm for the carbide and 0.87 ± 0.33 µm for the boride with minimal residual oxide (0.2 vol%) detected in the microstructure. The resulting composition had a higher microhardness than the individual boride and carbide ceramics across the range …

Parametric Optimization Of Friction Stir Welding Of Aa6061-T6 Samples Using The Copper Donor Stir-Assisted Material Method, Aiman H. Al-Allaq, Joseph Maniscalco, Srinivasa Naik Bhukya, Zhenhua Wu, Abdelmageed Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

This study presents an optimization of the process parameters for the effect of copper (Cu) donor material percentage on the friction stir welding (FSW) of AA6061-T6 alloy. Extensive factorial experiments were conducted to determine the significance of the rotational speed (ω), the transverse speed (v), the interface coefficient of friction (μ), and the Cu donor material percentage in the plunge, left, right, and downstream zones. Design Expert 13 software was used to identify the number of simulation experiments to be conducted using the Abaqus simulation software. From Design Expert 13, which is a thorough multi-objective optimization analysis software, we were …

A Comprehensive Review Of Piezoelectric Ultrasonic Motors: Classifications, Characterization, Fabrication, Applications, And Future Challenges, Sidra Naz, Tian-Bing Xu

Mechanical & Aerospace Engineering Faculty Publications

Piezoelectric ultrasonic motors (USMs) are actuators that use ultrasonic frequency piezoelectric vibration-generated waves to transform electrical energy into rotary or translating motion. USMs receive more attention because they offer distinct qualities over traditional magnet-coil-based motors, such as miniaturization, great accuracy, speed, non-magnetic nature, silent operation, straightforward construction, broad temperature operations, and adaptability. This review study focuses on the principle of USMs and their classifications, characterization, fabrication methods, applications, and future challenges. Firstly, the classifications of USMs, especially, standing-wave, traveling-wave, hybrid-mode, and multi-degree-of-freedom USMs, are summarized, and their respective functioning principles are explained. Secondly, finite element modeling analysis for design and …

Dual Airfoil Testing System, Zifeng Yang, Collin Charvat, Jack Stafford, Kyle Mathews, Logan Kelly

Mechanical and Materials Engineering Faculty Publications

A dual airfoil testing system includes a platform including a frame defining a chamber that is configured to receive a horizontal flow of air for testing a first airfoil and a second airfoil contained in the chamber and a control system including a controller to control a first attack angle stepper motor, a second attack angle stepper motor, at least one gap stepper motor, and at least one stagger stepper motor. The controller is configured to automatically control and adjust the stepper motors to control and adjust the attack angle of the first airfoil, the attack angle of the second …

Fabrication Of Smooth Sac305 Thin Film Via Magnetron Sputtering, M. Ojha, A. A. Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

SAC305 (96.5 wt% Sn, 3 wt% Ag, 0.5 wt%Cu) solder is increasingly becoming popular due to its reliability good characteristics and performance in addition to the environmental concerns and regulations that restrict the use of lead in nano/microelectronic products. In nano/microelectronics, manufacturing smooth solder coatings free of defects such as voids and cracks, which can compromise joint reliability is crucial. Magnetron sputtering offers a high degree of control over film thickness and composition, resulting in films with excellent uniformity and adhesion. Despite these advantages, fabricating continuous and robust SAC305 films using magnetron sputtering remains a difficult task with limited research …

Cf/Sic Ceramic Matrix Composites With Extraordinary Thermomechanical Properties Up To 2000 °C, Min Sung Park, Jian Gu, Heesoo Lee, Sea Hoon Lee, Lun Feng, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

The thermomechanical properties of carbon fiber reinforced silicon carbide ceramic matrix composites (Cf/SiC CMCs) were studied up to 2000 °C using high temperature in situ flexural testing in argon. The CMC specimens were fabricated using an ultrahigh concentration (66 vol%) aqueous slurry containing nano-sized silicon carbide powder. The SiC powder compacts were obtained by drying the slurry and were densified using the precursor impregnation and pyrolysis (PIP) method with field assisted sintering technology/spark plasma sintering (FAST/SPS). The high relative density of the SiC green body (77.6%) enabled densification within 2.5 days using four PIP cycles. In contrast, conventional PIP processes …

Phosphate-Based Dechlorination Of Electrorefiner Salt Waste Using A Phosphoric Acid Precursor, Paige Murray, Harmony Werth, Sean Sullivan, Brian J. Riley, Michael Simpson, Charmayne E. Lonergan, Krista Carlson

Materials Science and Engineering Faculty Research & Creative Works

Electrochemical processing of spent nuclear fuel in molten chloride salts results in radioactive salt waste. Chlorine removal from the salt has been identified as an effective and efficient first step in the management of high-level waste. In this work, a simple salt was dechlorinated with a phosphoric acid phosphate precursor, resulting in a glassy dechlorinated product. The dechlorination efficacy was evaluated in air and argon environments. This work serves as an initial step to advance the technological readiness level of h3po4-based dechlorination step toward implementation of iron phosphate waste forms to immobilize electrochemical fuel reprocessing salt waste streams.

Thermal And Electrical Properties Of Single-Phase High Entropy Carbide Ceramics, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz, Jeremy Lee Watts, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

Thermal and Electrical Properties Were Investigated for Five Nominally Phase-Pure High Entropy Carbide Ceramics. the Compositions (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)C, (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Ta0.2Ti0.2W0.2Zr0.2)C, and (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C Were Synthesized by Carbothermal Reduction of Oxides. the Thermal Diffusivity and Heat Capacity Were Measured from Room Temperature to 1800°C. the Room Temperature Thermal Conductivity Ranged from 5.1 W/mK for (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C to 9.0 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C. the Thermal Conductivity Increased over the Temperature Range with Maximum Conductivities of 19.6 W/mK Measured for (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C to 29.7 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C at 1800°C. the Electron Contribution to Thermal Conductivity Calculated from Measured Electrical Resistivity Varied from 41% to 52% of the …

Pressureless Sintering And Properties Of Additively Manufactured Zrb2–Sic, Marharyta Lakusta, Nicholas M. Timme, Jeremy L. Watts, William G. Fahrenholtz, Gregory E. Hilmas, David W. Lipke

Materials Science and Engineering Faculty Research & Creative Works

Densification behavior, grain growth kinetics, mechanical and thermal properties of pressurelessly sintered zirconium diboride–silicon carbide (ZrB2–SiC) fabricated by extrusion of high solids loading pastes have been studied. The effects of sintering temperature (1600–2300°C), heating rate during constant heating rate sintering (10–50°C/min), and time during isothermal sintering (3–24 h) on density and grain size were examined. The apparent activation energy for densification was determined to be 940 ± 90 kJ/mol, suggesting lattice diffusion as the dominant sintering mechanism. Grain growth of both ZrB2 and SiC followed a normal grain growth power law with grain growth exponent n = 2 indicating diffusion-controlled …

A Concept Of Producing Aluminum In-Situ On The Moon Through Molten Salt Electrolysis, Jacob N. Ortega, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daniel Stutts, Daoru Han

Materials Science and Engineering Faculty Research & Creative Works

This paper presents a concept of producing aluminum in-situ on the lunar surface, namely, the Lunar In-Situ Aluminum Production through Molten Salt Electrolysis (LISAP-MSE) method developed at Missouri University of Science and Technology. This paper aims to demonstrate the use of electro-deoxidation to reduce aluminum oxide (i.e., alumina) into aluminum and oxygen gas via electrolysis in a molten salt bath for the production of aluminum on the Moon. It is shown that with a steady supply of hydrogen chloride, this in-situ resource utilization (ISRU) method could supply several necessary materials consumed in the electro-deoxidation process except hydrogen chloride to produce …

Solvent-Free Manufacturing Of Lithium-Ion Battery Electrodes Via Cold Plasma, Zhiming Liang, Tianyi Li, Holden Chi, Joseph Ziegelbauer, Kai Sun, Ming Wang, Wei Zhang, Tuo Liu, Yang-Tse Cheng, Zonghai Chen, Xiaohong Gayden, Chunmei Ban

Chemical and Materials Engineering Faculty Publications

Slurry casting has been used to fabricate lithium-ion battery electrodes for decades, which involves toxic and expensive organic solvents followed by high-cost vacuum drying and electrode calendering. This work presents a new manufacturing method using a nonthermal plasma to create inter- particle binding without using any polymeric binding materials, enabling solvent-free manufacturing electrodes with any electrochemistry of choice. The cold-plasma-coating technique enables fabricating electrodes with thickness (>200 lm), high mass loading (>30 mg cm^-2), high peel strength, and the ability to print lithium-ion batteries in an arbitrary geometry. This crosscutting, chemistry agnostic, platform technology would increase energy density, …

Effect Of Resin Bleed Out On Compaction Behavior Of The Fiber Tow Gap Region During Automated Fiber Placement Manufacturing, Von Clyde Jamora, Virginia Rauch, Sergii G. Kravchenko, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

Automated fiber placement is a state-of-the-art manufacturing method which allows for precise control over layup design. However, AFP results in irregular morphology due to fiber tow deposition induced features such as tow gaps and overlaps. Factors such as the squeeze flow and resin bleed out, combined with large non-linear deformation, lead to morphological variability. To understand these complex interacting phenomena, a coupled multiphysics finite element framework was developed to simulate the compaction behavior around fiber tow gap regions, which consists of coupled chemo-rheological and flow-compaction analysis. The compaction analysis incorporated a visco-hyperelastic constitutive model with anisotropic tensorial prepreg viscosity, which …

Effect Of Post-Cured Through Thickness Reinforcement On Disbonding Behavior In Skin-Stringer Configuration, Jimesh D. Bhagatji, Christopher Morris, Yogaraja Sridhar, Bodhisatwa Bhattacharjee, Krishnanand N. Kaipa, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

An experimental investigation of interlaminar toughness for post-cured through-thickness reinforcement (PTTR) skin-stringer sub-element is presented. The improvement in the crack resistance capability of skin-stringer samples was shown through experimental testing and finite element analysis (FEA) modeling. The performance of PTTR was evaluated on a pristine and initial-disbond of the skin-stringer specimen. A macro-scale pin-spring modeling approach was employed in FEA using a non-linear spring to capture the pin failure under the mixed-mode load. The experimental results showed a 15.5% and 20.9% increase in strength for the pristine-PTTR and initial-disbond PTTR specimens, respectively. The modeling approach accurately represents the overall structural …

Mechanisms Of Dendritic Shorting In Lithium Metal Batteries With Li7la3zr2o12 Solid Electrolytes, Lukas Karapin-Springorum

Pomona Senior Theses

Energy storage will play a crucial role in efforts to mitigate the effects of climate change caused by greenhouse gas emissions from human activity. Lithium metal batteries using solid electrolytes like Li₇La₃Zr₂O₁₂ have higher energy density than lithium-ion batteries, which may enable a more rapid and complete electrification of transportation. However, lithium metal batteries suffer from undesirable short-circuiting when metallic lithium deposits connect the two electrodes. It has been debated whether these lithium dendrites generally grow directionally from the anode or are generated by the reduction of lithium ions inside the solid electrolyte, …

B(C₆F₅)₃ Co-Catalyst Promotes Unconventional Halide Abstraction From Grubbs I To Enhance Reactivity And Limit Decomposition, Austin W. Medley, Diya Patel, Calvin Utne, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

Ruthenium based Grubbs metathesis has become a commonplace reaction for synthetic chemists. Development of new generations of catalysts evolving from Grubbs I (GI) have led to greater stability, functional group compatibility, and superior reactivities. However, these advancements lead to increased costs. To this end, we report here how the addition of the commercially available tris(pentafluorophenyl)borane Lewis acid, which has become a common place catalyst in its own right, leads to enhanced reactivity of GI. Moreover, the increased reactivity arises via halide abstraction rather than traditional phosphine dissociation, providing ring-opening metathesis polymerization products that are divergent from those synthesized without the …

The Characterization And Nanomechanical Properties Of Microstructurally Complex Systems, Kerry Ann Baker

Theses and Dissertations--Chemical and Materials Engineering

Since the dawn of civilization, the use of metals has played an integral role in the evolution of human society. Over the years, and with the introduction of new engineering and science, we have learned how to combine metals to create new metallic systems. We have expanded our understanding of dealloying and chemical reactions, and, in doing so, we created nanoporous metals. Our use of metals has evolved from basic alloys such as bronze and steel to more complex alloys such as multi-principal element alloys. Nanoporous gold is an advanced metallic system that can be created through the dealloying process. …

Advancing Combinatorial Screening Of Refractory High Entropy Alloys Through Intrinsic Ductility Assessment Via Thin Film Fragmentation Testing, Taohid Bin Nur Tuhser

Theses and Dissertations--Chemical and Materials Engineering

High Entropy Alloys (HEAs), also known as Multiprincipal Element Alloys (MPEAs), represent a paradigm shift in alloy design. Unlike traditional practices that limit compositions to the edges of phase diagrams, HEAs exploit equiatomic mixing of five or more elements at the center of phase diagrams to maximize configurational entropy. This unconventional approach exponentially expands the spectrum of potential alloy compositions, rendering conventional experimental methods inadequate for exploring this extensive compositional space.

In response to these challenges, the scientific community has shown a growing interest in high-throughput techniques, encompassing both computational and experimental domains. Particularly, Refractory High Entropy Alloys (RHEAs) have …

Microstructural Investigation Of The Influence Of Geometry On The Mechanical Reliability Of Additively Manufactured Metals, Tracy Connor Varney

Theses and Dissertations--Chemical and Materials Engineering

The adoption of additive manufacturing across a wide range of fields is ever-increasing, allowing for solutions that were previously impossible to achieve. This dissertation demonstrates the wide range of macro- and micro- characterization techniques used to investigate several precipitation strengthened AM alloy systems. While AM allows for nearly unlimited design freedom, this brings along its own issues as the interplay between scan strategy and part geometry is less well known. In this work, a novel thin-wall dogbone geometry was utilized to study one type of complex geometry observed in a large portion of AM focused designs. The mechanical behavior of …

Optoelectrical Properties And Photostability Of Cspbbr3 Quantum Dots: Effects Of Dopants And Ligands, Md Shad Bin Salam

Theses and Dissertations--Chemical and Materials Engineering

Metal halide perovskite QDs have a great potential for displays and lighting because of their exceptional optoelectronic characteristics associated with quantum confinement effect. However, the stability in the environment during the applications of halide perovskite QDs remains a significant challenge, impeding their practicality and lowering their commercial scalability. High-temperature methods are well-established for producing doped perovskite QDs, the influence of room-temperature synthesis on thermal, size-dependent optical properties, and long-term stability remains inadequately understood. Also, there is a demand for strategies to increase the absorption of light, reduce trap states, and modify the energy levels of perovskite QDs.

In this study, …

Thermal Alteration Of The Mineralogy Of Calcium Sulfoaluminate Cements: Implications For The Performance Of Rapid Repair Materials, Jillian Cavellier

Theses and Dissertations--Earth and Environmental Sciences

Calcium sulfoaluminate (CSA) was developed in part to lessen the environmental impact of cementitious materials compared to traditional Portland cements. CSA was first put into production in the 1970s and has been undergoing various performance testing to investigate its durability. Yet to be evaluated is CSA’s response to a rapid, high temperature event. In this study, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectrometry and scanning electron microscope imaging were used to analyze alterations in the mineralogy due to such an event. As found in previous studies, after ~125°C, ettringite has been completely dehydrated. Ettringite decomposes into bassanite and calcium …

Mechanochemical Synthesis Of Halide Perovskite Microcrystals, Xuan Huang

Theses and Dissertations--Mechanical and Aerospace Engineering

Halide perovskites have emerged as a promising class of materials for various optoelectronic applications, including light-emitting diodes (LEDs), solar cells, photodetectors, and lasers, owing to their exceptional photophysical properties and ease of synthesis. Lead-based halide perovskites, despite their success, raise concerns regarding environmental toxicity, necessitating the exploration of lead-free alternatives. This thesis explores the synthesis and characterization of lead-free halide perovskites, focusing on tin-based variants, using a mechanochemical approach, which eliminates the use of toxic solvents and offers a sustainable synthesis route.

By employing a solventless mechanochemical method, lead-free tin-based halide perovskite microcrystals were successfully synthesized. This approach not only …

Halide-Assisted Growth Of Transition Metal Dichalcogenides, Vinaayak Sivam Balasubramaniam

Dissertations, Master's Theses and Master's Reports

Monolayers of transition metal dichalcogenides (TMDCs) have attracted significant attention as the rare two-dimensional (2D) semiconducting materials with a direct energy band gap. Chemical vapour deposition (CVD) is one of the scalable techniques to grow atomically thin TMDC monolayers in high quality, but it requires high growth temperature. Herein we report the growth of MoS2, WS2 and MoSe2 by a one-step halide-assisted CVD method using NaCl and KCl as the catalysts. These halides could reduce the growth temperature of TMDCS by reacting with the precursors (TMDC powders) to form volatile intermediate compounds as the growth species. We use optical microscopy, …

Fatigue Resistant Cast Steel Railcar Couplers Produced By Wire-Arc Additive Manufacturing (Waam), Samuel Vellequette

Dissertations, Master's Theses and Master's Reports

Every year, approximately 90,000 cast steel railcar coupler knuckles are replaced preemptively to avoid fatigue failure. The coupler geometry has been in service since the early 1930s, so geometry changes are restricted to maintain compatibility with the existing fleet. Defects from the casting process, decarburization during heat treatment, and in-service exposure to corrosive environments combine to promote fatigue crack nucleation in high-stress regions of the knuckle. Wire-arc additive manufacturing (WAAM), which uses traditional welding techniques to build material to near-net shapes, was employed to deposit higher-strength materials in critical regions. By replacing the cast steel in the high-stress region of …

Calculation Of Elastic Constants Of Bulk Metallic Glasses From Indentation Tests, Zhitong Xu, Ming Liu, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

One of the challenges in the applications of instrumented indentation is to simultaneously measure elastic modulus and Poisson’s ratio of homogeneous, isotropic materials. This work proposes empirical equations for simultaneous calculation of elastic modulus and Poisson’s ratio of bulk metallic glasses (BMGs) from the ratio of the short diagonal length to the long diagonal length and the area of the Knoop imprint. The parameters pre- sented in the empirical equations are determined first by Knoop microhardness tests of 24 BMGs, whose elastic moduli and Poisson’s ratios are measured by resonant ultrasound spectroscopy. These empirical equations are further validated by the …