High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond II: Processing and Properties III
Sponsored by: TMS Alloy Phases Committee, TMS Mechanical Behavior of Materials Committee
Program Organizers: Michael Gao, National Energy Technology Laboratory; Xingbo Liu, West Virginia University; Peter Liaw, University of Tennessee; Jian Luo, University of California, San Diego; Yiquan Wu, Alfred University; Yu Zhong, Worcester Polytechnic Institute; Mitra Taheri, Johns Hopkins University; Amy Clarke, Los Alamos National Laboratory
Wednesday 2:00 PM
October 20, 2021
Room: B132
Location: Greater Columbus Convention Center
Session Chair: Fei Wang, University of Nebraska Lincoln
2:00 PM
Behavior of a High-entropy Alloy in Molten Salt Environments under Biaxial Stresses
: Wylie Simpson1; James Earthman1; Xinyi Wang1; 1University of California Irvine
Aerospace vehicles and the boilers of off-shore industrial rigs that operate near the ocean or desert are exposed to salts that can melt at high temperature and produce hot corrosion, which reduces the service life of the component or vehicle. Corrosion resistance of materials in molten NaCl-Na2SO4 salt is achieved by formation of dense protective oxide film on materials surface, which prevents further corrosion of materials underneath However, the corrosion database for NaCl-Na2SO4 molten salts is still limited. Further investigation for reliable selection of compatible materials is needed. High Entropy Alloys (HEAs) have emerged as attractive candidate materials due to their good corrosion resistance and mechanical properties. The present study will focus on the influence of bi-axial stress on the corrosion behavior of Al0.1CoCrFeNi HEAs in NaCl-NaSO4 molten salts.
2:20 PM
Control of Local Distortions in High-entropy Oxides: Keivan Esfarjani1; Jonathan Kaufman1; 1University of Virginia
Lattice distortion in high entropy alloys is postulated to have major effects on these alloys and their properties. There are limited studies that look at the effect of lattice distortion on entropy-stabilized oxides. In this study, we explore the effect of bond strength, atomic size and temperature on distortions in the entropy-stabilized oxide, MgCoNiCuZnO5. This work uses molecular dynamics to identify the explicit distances that each atom and atom type distorts from its parent rocksalt crystal structure as a function of temperature. This study shows that this material can be optimized to either increase or decrease the total lattice distortion in the system by appropriately changing the atomic composition or by replacing certain elements with alternative elements. Details of our findings will be discussed in this talk.
2:40 PM
Microstructure and Phase Stability of High Entropy (RE)PO4 Monazite-structured Ceramics: Nadjia Motley1; Adriana Mejia1; Yingie Yang1; Daniel Mumm1; Martha Mecartney1; 1University of California, Irvine
Although monazite structured ceramics (REPO4) demonstrate exceptional thermal, chemical, and radiative properties, they are known to be challenging to process, with relatively low mechanical strength. Single-phase monazites form with larger atomic-sized lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu Gd). In this work, we explore the effects of atomic size variation on the microstructure and mechanical properties of single-phase high-entropy monazite by incorporating lanthanides that tend to form the ordered xenotime crystal structure (Tb, Dy, Ho, Er, Tm, Yb, Lu). Preliminary results indicate the formation of single-phase multicomponent monazite via direct precipitation synthesis, incorporating up to six elements (La, Ce, Eu, Gd, Tb, Dy). The phase formation, phase stability, and grain growth are characterized using X-ray diffraction and scanning electron microscopy. By experimentally clarifying the microstructural and phase stability, we present a strategic method for enhancing ceramic oxides' thermal and mechanical properties.
3:00 PM
Surface Enhancement of Multi-principal Element Alloys by Gas Nitriding: Yu-Hsuan Lin1; David Poerschke1; 1University of Minnesota
The large and flexible compositional space of multi-principal element alloys (MPEAs) provides new opportunities to tune alloy chemistry for better properties. In addition to optimizing the bulk properties, this superior characteristic also enables the development of new surface enhancement strategies for improved wear and corrosion resistance. This work focuses on devising strategies to design transition- and refractory-metal MPEAs for the formation of multi-principal element nitride coatings and graded interstitially-hardened structures with desired microstructures and properties via direct alloy conversion. Building on the insights from the study of growth kinetics and properties of the nitrided zone for nitride-forming pure metals including Hf, Mo, Nb, Ta, Ti, and Zr, computational thermodynamics screening was used in conjunction with combinatorial MPEA fabrication to identify promising alloy compositions. This combined computational-experimental approach aims to efficiently test a wide range of compositions, and narrow down candidates having high strength and good surface durability after nitriding.
3:20 PM
Structural and Mechanical Properties of High Entropy Metal-nitride: Saro San1; Wai-Yim Ching2; 1University of Missouri; 2University of Missouri Kansas City
High entropy metal-nitrides (HENs) are a new developing area with the potential of functional materials. Binary and ternary transition metal-nitride were well recognized in the last three decades. Incorporating high entropy alloys with nitride is needed to modify TM-nitride properties. We report the results of first-principles calculations of 4 HEN using large supercells of 512 atoms in a single-phase rock-salt fcc structure. The transition metals are randomly distributed at the cation site. The optimized structures using VASP are used to calculate the electronic structure, interatomic bonding, and mechanical properties of 4 HENs. We use the novel concept of total bond-order density (TBOD) and its partial components based on the quantum mechanical metric for internal cohesion. The results show that the HEN containing Al have higher TBOD with smaller volume, and AlCrMoTaTiN possesses the highest elastic moduli and more ductile. These findings are valuable for understanding and designing HENs.
3:40 PM Break
4:00 PM
Multi-component High Entropy Ultra-high Temperature Carbides: Solid-solution to High-entropy Phase Formation: Ambreen Nisar1; Tyler Dolmetsch1; Tanaji Paul1; Cheng Zhang1; Benjamin Boesl1; Arvind Agarwal1; 1Florida International University
The development of a new class of high entropy-ultra high temperature ceramics (HE-UHTCs) has gained increased interest due to the possibility that they can possess enhanced thermo-mechanical properties unattainable by conventional UHTCs. Though a large number of HE-UHTCs have emerged, the understanding on the factors such as solid-solutioning, entropy, and multi-component, contributing to the remarkable enhancement in the properties is still in a nascent stage. In this regard, systematically the constituents in a UHTCs were raised from monoliths to binary to ternary and then quaternary in (Ta,Nb,Hf,Ti)C UHTC system. The four-component system is expected to form HE-UHTCs whilst others showed mere solid-solutioning. Dense samples were produced using spark plasma sintering (SPS) at 1850 °C. This work will delineate the contributions of solid-solutioning vs high entropy towards enhancing thermo-mechanical properties in a multi-component UHTC carbide system.
4:20 PM
The Dynamic and Sensing Performance of 3D Printed Functionally Graded Elastomeric Lattice Structures: Charles Dwyer1; Joao Garretto1; Ronald Yarwood1; Jae-Won Choi2; Eric MacDonald3; Pedro Cortes1; Gina Morrison1; 1Youngstown State University; 2University of Akron; 3The University of Texas at El Paso
Additive manufacturing has enabled the creation of functionally graded complex lattice structures that had not been possible to construct before. When made of elastomeric polymers, these lattices can be used as protective padding in place of conventional foams. New methods of manufacturing also allow the materials themselves to vary within structures, leading to more customizable impact force and displacement profiles. Functionally graded materials have been shown to absorb energy more efficiently than non-graded materials, leading to decreased risk of personal injury. The use of these graded lattice paddings includes industries such as military, emergency services, and sports, specifically in National Football League helmets. The method of construction of these materials also allows for the incorporation of electronic sensors within the structure, without interrupting the lattice design. Integration of sensors inside helmet protection will wirelessly transmit data about its impacts in near real-time and can lead to safer sports in general.
4:40 PM
Temperature Dependent Mechanical Behavior of the Au-Zn-Al Ternary System: Taylor Jacobs1; Seth Imhoff1; 1Los Alamos National Laboratory
Ternary Au-Zn-Al alloys are under investigation as non-radioactive, high density materials with complex phase transformations. Additionally, these alloys also have demonstrated relatively high strengths with moderate ductility. For example, recent mechanical testing of Au65Zn30Al5 shows yield and ultimate compressive strengths of 550 and 1230 MPa, respectively. The purpose of this study is to characterize the temperature dependent mechanical properties of Au65Zn30Al5 and investigate the influence of Al additions on strength in Au75Zn25+Alx (x = 0, 0.5, 1, 2, 3.5, 5, and 8 at pct). Microstructures of these alloys tend to be dual phase, heavily twinned, non-equiaxed grains, within visible prior-(α, α1, or β’) grain boundaries (i.e. the high temperature phases of the Au-Zn binary system). The highly twinned microstructures are compared to the observed mechanical properties. The results of this study are combined with thermophysical property characterization and modeling efforts to improve fundamental understandings of processing high density metal alloys.
5:00 PM
The Research Thermoplastic Deformation Modes of Dual-phase Special Alloys for Obtaining Rational Intermetallic Structure: Borys Sereda1; Dmytro Sereda1; Irina Kruglyak1; Yuriy Belokon2; 1Dneprovsky State Technical University; 2Zaporizhzhya National University
The purpose of this work is to investigate the structure formation in intermetallic γ-TiAl alloys by using a complex plastic deformation technology under non-stationary temperature conditions with niobium doping. Mathematical model aimed at obtaining γ-TiAl alloys with a given structure and properties is proposed and implemented, based on the use of data on the features of the physical modeling of the SHS-pressing process. For a mathematical description of the process of extrusion of a high-temperature synthesis product, it is necessary to determine a system of equations that takes into account the distribution of the thermo-kinetic and rheological properties of the synthesis product in a mold and caliber. High-temperature synthesis of intermetallic compound γ-TiAl in a powder mixture of pure elements in the conditions of SHS-pressing allows to obtain an intermetallic alloy with an average grain size of ~ 30 microns.