2023 Technical Division Student Poster Contest: SMD 2023 Technical Division Graduate Student Poster Contest
Program Organizers: TMS Administration
Monday 5:30 PM
March 20, 2023
Room: Exhibit Hall G
Location: SDCC
SPG-44: Advanced Characterization of the Local Atomic Orders and Their Effects on the Mechanical Properties in Metallic Glasses: Can Okuyucu1; Doguhan Sariturk1; Fatma Saadet Guven1; Emel Erdal1; Yunus Eren Kalay1; 1Middle East Technical University
Both marginal and bulk metallic glasses are new and exciting fields of study in materials science and solid-state physics. Their higher strength, corrosion resistance, and better elastic properties are very promising, considering their traditional counterparts. The reason behind these remarkable properties is investigated concerning the effect of local atomic arrangements. The structure and property relationship of these materials are studied by conventional and synchrotron X-ray diffraction, transmission electron microscopy, atom probe tomography, micropillar compression experiments, molecular dynamics studies, and some conventional methods like DSC and SEM. At the end of this study, the structural reason for the property enhancement of these amorphous metals has been tried to be enlightened.
SPG-45: Atomistic Modeling of Energy Barriers to Dislocation Processes in Metals: Yipin Si1; Ting Zhu1; 1Georgia Institute of Technology
Dislocation plays an important role in plastic deformation of crystalline solids. We perform nudged elastic band(NEB) calculations to determine the Peierls barrier and Peierls stress for dislocations glide in face-centered cubic nickel. The minimum energy paths(MEPs) across multiple Peierls barriers are determined under different shear loads. The effects of boundary condition and system size on Peierls barriers are studied by comparing strain- and stress-controlled NEB results. The free-end NEB methods are used to compute MEPs for long, highly tilted reaction paths. We further use NEB methods to determine the MEPs and energy barriers of competing processes, vacancy clusters cutting and cross-slip of screw dislocation in Ni. The effects of the obstacle sizes and spacings to the rate-controlling process are revealed. Our work demonstrates how to achieve accurate and efficient quantification of the barriers of different dislocation processes in metals and provides a basis of the investigation of compositionally complex alloys.
SPG-46: Automating Selective Area Electron Diffraction Pattern Phase Identification Using Image Analysis and Machine Learning: Mitchell Mika1; Assel Aitkaliyeva1; 1University of Florida
Selective area electron diffraction (SAED) patterns can provide valuable insight into the structure of a material. For example, SAED patterns can be used to identify phase transformations such as those occurring during constituent redistribution in metallic nuclear fuels. The phase identification is conducted by matching experimentally collected SAED patterns to those simulated using various software. This process is time-intensive when done manually for each diffraction image and can create a bottleneck in the workflow of characterizing materials. In this contribution, we utilize the recent advances in computer vision and machine learning (ML) to automate the indexing of electron diffraction patterns. We utilize image analysis techniques and ML algorithms to introduce an open-source workflow that accelerates the processing of electron diffraction patterns. The phase identification is based on experimentally acquired SAED patterns and is demonstrated on metallic Pu-based alloys.
SPG-47: Bulk Material Libraries through Laser-Remelting: Combinatorial Analysis of the CrCoNi System: Tobias Gaag1; Maximilian Heidowitzsch1; Carolin Körner1; Christopher Zenk1; 1Friedrich-Alexander-Universität Erlangen-Nürnberg
Conventional methods of alloy discovery are very time-consuming and expensive, especially for challenging material systems such as superalloys. Material libraries that allow the measurement of bulk material properties can significantly accelerate alloy design efforts. Surface remelting of specimens of varying compositions in contact with each other can be used to create a composition gradient through intermixing, and therefore produces such bulk material libraries. Herein, Laser surface-remelting was employed to create bulk material libraries of the CrCoNi system, as a model system for a superalloy γ-phase composition. Average intermixing distances of approximately 4 mm were achieved, resulting in well-defined composition gradients. Microstructure and mechanical properties were determined and related to the local composition. The material library was used as a proof-of-concept to identify phase boundaries and verify solid-solution-strengthening models in the fcc single-phase region. In summary, the potential for accelerated structural material discovery is demonstrated.
SPG-48: Corrosion Control of Structural Materials for 4th Gen Nuclear Reactors: Krishna Moorthi Sankar1; Preet Singh1; 1Georgia Institute of Technology
One of the major issues in the design of Molten Salt Nuclear Reactors (MSRs) is the significant corrosion of structural materials in the coolant salts such as FLiNaK. The corrosion depends on the redox potential of the system, which in-turn depends on the type and amount of impurities present in the molten salt as well as the alloy composition of the structural material. In this study, corrosion behavior of selected Ni and Fe based alloys were studied in molten FLiNaK at 700 oC. Different redox control methods such as salt purification to remove impurities, addition of active elements as corrosion inhibitors, and electrochemical redox control were tested to understand their effect on this corrosion. This presentation will discuss our results on the viability and effectiveness of various corrosion control methods in molten FLiNaK salt under MSR conditions.
SPG-49: Deformation Mechanism Characterization for Bi-modally Distributed γ' Precipitates in Allvac 718plus Superalloy: Geeta Kumari1; Carl Boehlert1; S Sankaran2; M Sundararaman2; 1Michigan State University; 2Indian Institute of Technology, Madras
Alloy Allvac 718Plus was developed to improve the properties of the Inconel 718, which resulted in service temperatures up to 704ºC (55ºC more than IN718). The dominant deformation mechanisms change with the change in size and distribution of the γ' precipitates. When the γ' precipitates are larger in size, dislocations tend to loop around them, whereas when the γ' precipitates are smaller, the dislocations tend to shear through them. A bimodal γ’ precipitate distribution was developed using a two-step aging treatment at 720℃ for 10h and 900℃ for 2h, which resulted in 14 nm smaller and 55 nm larger precipitates. After the heat treatment, interrupted tensile deformation experiments were conducted. Transmission electron microscopy was used to study the particle-dislocation interactions. The same set of experiments was repeated on samples having a uni-modal precipitate distribution and the results were compared. This will help develop a model involving multi-modal distribution of precipitates.
SPG-50: Effect of Ag on the Microstructures in Al-Cu-Ni-Mn High Entropy Alloy: Gina Zavala Alvarado1; S.K. Varma1; Mckenna Hitter1; 1The University of Texas at El Paso
The effect of Ag on the microstructure developed in Al-Cu-Ni-Mn alloys has been determined. In the as-cast condition, three phases were found and characterized by compositional differences rich in (1) Cu, (2) Ag, and (3) Ni. The compositions of the phases in the alloy may be related to the atomic radii of the elements in the phases. Static oxidation has been performed at 600, 700, 800, 900, and 1000°C for 24 hours in air. The oxides present on the surface were identified. The results have been compared with the microstructures affected by the addition of Si on the same quaternary alloy from a previous study. The silver-rich phase is an analog of the Mn-rich phase developed by the addition of Si in this alloy as reported previously by the authors.
SPG-51: Experimental Observation of Heteroepitaxial Recrystallization (HeRX) outside of Low Lattice Misfit Ni-based Superalloys: Yonguk Lee1; Eitan Hershokovitz1; Honggyu Kim1; Eric Payton2; Victoria Miller1; 1University of Florida; 2University of Cincinnati
Heteroepitaxial recrystallization (HeRX) is a promising mechanism for grain size control, but has only been reported in Ni-based superalloys with low lattice misfits that have negligible interfacial energy for epitaxial templating. In this study, HeRX is induced in LSHR—a polycrystalline Ni-based superalloy with misfit greater than the conventional limit for HeRX—and scanning TEM and EDS is performed at the γ-γ' interface of grain that had undergone HeRX. Atomic resolution STEM performed along the [112] zone axis reveals strong coherency across the γ-γ’ interface, demonstrating HeRX in an intermediate lattice misfit Ni-based superalloy for the first time. This finding infers that the small lattice misfit is not a strong prerequisite for the onset of HeRX, and therefore, suggests that there is a much wider range than initially believed of processing conditions under which HeRX can be used as a tool for microstructural control in Ni-based superalloys.
SPG-52: Investigation of Corrosion Mechanisms and Fatigue Property of Friction-stir Welded Joints between 6022 Al and ZEK100 Mg Alloy: Qingli Ding1; 1Worcester Polytechnic Institute
Friction Stir Welding (FSW) is a solid-state welding method which is widely used in the automotive industry. The Friction stir welded Aluminum to Magnesium alloy shows better quality joint properties, such as good microstructure stability, high tensile strength and ductility which has very good potential for vehicle parts. This study focuses on learning the mechanism of corrosion behavior of FSW joint between 6022 Al and ZEK100 Mg which includes the grain size and intermetallic effect. The property of intermixing zone is analyzed through electrochemical tests. The mechanical property will mainly examine the fatigue property before and after keeping the specimen into a Cyclic Corrosion Chamber (CCT).
Cancelled
SPG-53: Methods for Estimating the Microscopic and Macroscopic Behaviors of Materials: Mathew Aibinu1; Kemi Adewale2; Joba Morakinyo3; 1Durban University of Technology; 2University of KwaZulu-Natal; 3Ladoke Akintola University of Technology
Fractional derivatives are suitable in describing several physical phenomena. The construction of efficient analytical and numerical methods for the solutions of ordinary and partial fractional differential equations is an active research area and it is of great interest to the researchers. The Caputo fractional derivative is of great use in the modelling and simulation of phenomena where consideration is given to the interactions within the past and problems with nonlocal properties. This study introduces an approximate analytical method for constructing the solution of nonlinear equations with delay and of Caputo fractional derivative, which describes the processes in the functional and structural materials. The study is of great importance in the numerical and experimental characterization of the properties of the composites.
SPG-54: Microstructural Characterization and Oxidation of Non-BCC High Entropy Alloys: Mckenna Hitter1; S.K. Varma1; 1University of Texas at El Paso
Al-Cu-Ni-Mn and Al-Cu-Ni-Mn-Si high entropy alloys have been made in equi-atomic proportions. Both alloys were exposed to oxidation in air for 24 hours at 600, 700, 800, 900, and 1000OC. The as received and oxidized microstructure of the alloys have been characterized using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Three phases have been identified in each alloy in the as received condition. Both alloys contain a Ni rich phase and a Mn rich phase. The quaternary alloy has a phase rich in Al-Cu-Ni and the quinary alloy has a phase rich in Al-Cu-Mn. Oxides and intermetallics have also been recognized after oxidation at each temperature, respectively.
SPG-55: Modeling of Non-equilibrium Phenomena in Laser Additive Manufacturing Using Molecular Dynamics: Gurmeet Singh1; Veera Sundararaghavan1; 1University of Michigan
Additive manufacturing of a single crystalline metallic column is studied using molecular dynamics simulations. In our previous work, a melt pool is incrementally added and cooled to a target temperature under isobaric conditions to build a metallic column. We investigated the microstructure evolution of the solidified column and looked at the influence of cooling rate, powder bed temperature, and effect of added inclusion on the defects. In this work, we use the tight-binding DFT potentials to model multi-component alloy systems and the use of this approach to investigate the laser-atom interactions. Current laser-matter interaction models use two-temperature classical potentials that do not capture the electronic effects accurately. With DFT tight binding dynamics, we study how the laser interacts with various atom types in higher detail. We study the role that inclusions play in laser and matter interaction.
SPG-56: Nanoscale Differences in Tooth Enamel with Aging by Atom Probe Tomography: Jack Grimm1; Cameron Renteria1; Arun Devaraj2; Dwayne Arola1; 1University of Washington; 2Pacific Northwest National Laboratory
Dental enamel, the hardest tissue in the human body, endures decades of mastication and other functions without catastrophic failure. At the nanoscale, this biological composite consists of hydroxyapatite mineral nanocrystals surrounded by a thin (several nm) layer of amorphous mineral and organic residues. These intergranular components, as well as the hierarchical microstructure of this tissue are hypothesized to be responsible for the exceptional resistance to fracture. However, the enamel of adult teeth becomes increasingly brittle and prone to fracture with chronological aging. Compositional changes induced by extended exposure to the oral environment are undoubtedly responsible for the embrittlement of enamel with age but are not well understood. This study applies atom probe tomography to compare composition with nanometer resolution between teeth from young and old donors. The older tooth showed a decrease in organic content and an increase in trace ions in the intergranular region, corresponding with increased brittleness.
SPG-57: Sintering and Densification Mechanism of HfB2 Based Ultra High Temperature Ceramics for Hypersonic Space Vehicles: Shruti Dubey1; Kantesh Balani1; 1Indian Institute of Technology
HfB2-based ultra-high temperature ceramics (UHTCs) are used as protective tiles for nose cones and leading edges of the re-entry vehicles. The present work assesses the effect of temperature on densification and sintering kinetics of HfB2-based ceramics consolidated via spark plasma sintering. Pure HfB2 was sintered at temperatures ranging from 1750–1950°C under a constant uniaxial pressure of 50 MPa. Maximum densification of ~98% was achieved at > 1850°C. Moreover, the sintering kinetics have been studied utilizing a densification data and employing a model based on the creep deformation of materials. The stress exponent (n) < 2 corresponds to temperatures between 1750–1850°C, demonstrating that diffusion is the major densification mechanism. However, n was > 2 above 1850°C, indicating a transition from diffusion-based to dislocation-based densification mechanisms. This study establishes a solid foundation for a comprehensive understanding of the sintering mechanism and the rationale behind densification in HfB2 based UHTCs.
SPG-58: Thermal Stability of Novel Multicomponent Al-based High-performance Alloys and Its Direct Implication on Their Mechanical Properties: Gourav Mundhra1; Hao-En Peng2; Jien-Wei Yeh2; B. S. Murty3; 1IIT Madras and NTHU Taiwan; 2NTHU Taiwan; 3IIT Madras and IIT Hyderabad
There is a never-ending quest for lightweight metallic materials in transportation. Al-based alloys suffer from abysmal softening resistance at high temperatures (HT). Here, we present a striking advance in the understanding of thermal stability and its direct implication on the mechanical properties of novel Al-based nanoalloys. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), advanced scanning/transmission electron microscopy (S/TEM) revealed that the microstructure of these alloys is exceptionally stable even after prolonged exposure of 240 hrs. at temperatures ranging from 400 to 600 ℃, i.e., 72% to 94% of the melting point of Al. Room temperature nanoindentation tests revealed exceptional retention in nanomechanical properties even after prolonged HT exposure. Bending tests and fractographic analysis after prolonged thermal exposure revealed that our ultra-strong alloys were deformable and exhibited a ductile failure mechanism. These newly developed lightweight alloys have the potential for aerospace applications requiring materials with superior structural stability and mechanical endurance.
SPG-59: Understanding Nanostructures in the Binary Ti-Fe Alloy Using Advanced Electron Microscopy: Deepak Pillai1; Dian Li1; Cameron Tucker1; Ahsan Habib1; Yufeng Zheng1; 1University of Nevada, Reno
The microstructure evolution in the metastable beta titanium alloys can be effectively tuned using a variety of nanostructures such as omega phase, O’ phase, and O’’ phase. Recently, a novel nanostructure, named as incommensurate omega phase, was found in the Ti-Fe based alloys. The incommensurate omega phase was reported to show a different crystal structure compared with the hexagonal structure athermal or isothermal ω phase. In this work, the nanostructures in the Ti-Fe binary alloy were investigated using advanced scanning electron microscopy and transmission electron microscopy. The relationship between the Fe concentration and the nanostructures in Ti-Fe alloy was studied systematically using experiment. The influence of these nanostructures on the precipitation of omega phase and alpha phase during different heat treatment will be introduced. This work is supported by the NSF CAREER Award, grant DMR – 2145844.
SPG-60: Understanding the Microstructural Evolution in the Modeled Ti-18Mo-5Al Alloy Using Scanning Electron Microscopy: Ahsan Habib Munna1; Dian Li1; Yufeng Zheng1; 1University of Nevada Reno
The properties of the titanium alloys can be tuned by the manipulation of microstructural evolution of alpha precipitates during heat treatment process. Recent studies have shown that by adopting different heating rates during heat treatment, various fine-scaled alpha precipitates can be generated in the metastable beta titanium alloys. In this study, we used the modeled Ti-18Mo-5Al (wt.%) as an example to investigate the microstructural evolution during different heat treatments using advanced scanning electron microscopy (SEM). Different sizes of alpha precipitates were observed at the grain boundary and in the interior of gains, via SEM backscattered imaging. The size, morphology and number density of alpha precipitates were analyzed using the MIPARTM image processing software. The microstructural evolution pathway during different heat treatments will be discussed. This work is supported by the NSF CAREER Award, grant DMR- 2145844.