High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond III: Poster Session
Sponsored by: TMS: Nanomaterials Committee
Program Organizers: Yu Zhong, Worcester Polytechnic Institute; 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; Mitra Taheri, Johns Hopkins University; Amy Clarke, Los Alamos National Laboratory
Monday 5:00 PM
October 10, 2022
Room: Ballroom BC
Location: David L. Lawrence Convention Center
E-10: Characterization of Microstructure and Properties of Al2FeCoNiCu High-entropy Alloy: Lucy Hunter1; Matthew Kestenbaum1; Juan Palominos1; Ryan Thompson1; Mohsen Kivy1; 1California Polytechnic State University
In this study, the microstructure and properties of Al2FeCoNiCu high-entropy alloy (HEA) were investigated. The HEA was cast using an induction furnace and homogenized at 550oC. X-ray fluorescence (XRF) was used to confirm the composition of the alloy. A phase diagram that was calculated using Thermo-Calc with the TCHEA5 database showed two bcc phases and one fcc phase stabilized at room temperature. The presence of these phases was confirmed using X-ray diffraction (XRD). Optical micrographs of as-cast and homogenized samples revealed a dendritic (DR) and an inter-dendritic (ID) regions within the microstructure. Energy dispersive spectroscopy (EDS) determined that the ID regions were copper-rich while the DR regions had near equi-atomic composition. The HRC and HV showed overall high hardness with a slightly higher hardness value for the homogenized samples compared to the as-cast. Corrosion testing was performed in a 0.5M salt bath to observe corrosion rates within each region.
E-11: Development of Oxide Melt Solution Calorimetry for High Entropy Ceramics: Stuart Ness1; Scott McCormack1; 1University of California, Davis
High entropy ceramics are a field of growing interest. Since the description of 5-component oxides in 2016, a variety of high entropy ceramics have been described. These include other species of high entropy oxides, as well as 5-component carbides, nitrides, and diborides. However, there is a general lack of experimental formation enthalpies and mixing enthalpies available for these materials. One reason for this paucity of data is the difficulty in applying traditional calorimetric techniques (such as direct reaction or bomb calorimetry) to materials with many components. A promising solution to determine enthalpies of mixing and of formation in high entropy systems is oxide melt solution calorimetry (OMSC). In this work we demonstrate how OMSC can be adapted to measure formation enthalpies in high entropy oxides, carbides, nitrides, and diborides. This work also reports current calorimetric progress for high entropy ceramics, highlighting strengths and strategies for OMSC of high entropy ceramics.
E-12: Exploration of High-ductility Ternary Refractory High-entropy Alloys Using First-principle Calculations and Machine Learning: Hyo-Sun Jang1; Jin-Woong Lee2; Kee-Sun Sohn2; Jiwon Park1; Chang-Seok Oh1; 1Korea Institute of Materials Science (KIMS); 2Sejong University
Refractory bcc high-entropy alloys are in the spotlight as high-temperature materials due to their high strength at high temperatures but show poor ductility at room temperature. To improve the poor ductility, we utilized Pugh's shear-to-bulk modulus ratio, which is widely adopted to distinguish the ductility and brittleness of metals. In this study, the Pugh's ratio was investigated for the ternary refractory high-entropy alloy systems, as a first step toward exploring new high-ductility refractory high-entropy alloys. We first calculated elastic constants of various alloy systems and compositions using first-principles calculations based on the exact muffin-tin orbitals method combined with the coherent potential approximation. Using the calculated data, machine learning methods including neural networks and genetic algorithms were used to explore the optimum alloy with the highest Pugh's ratio.
E-13: High-throughput Design, Synthesis and Characterization of W-based Refractory High-entropy Alloys: Cafer Melik Ensar Acemi1; William Trehern1; Eli Norris1; Brent Vela1; Raymundo Arroyave1; Ibrahim Karaman1; 1Texas A&M University
Refractory alloys, including tungsten alloys, are promising for high-temperature applications due to their high strength at elevated temperatures, high thermal conductivity, low thermal expansion coefficient, and resistance to creep. Thirty refractory high-entropy alloys with tungsten contents of more than 30 at.% are designed to have single BCC phase region at high temperatures, a target yield strength at 2000°C and a narrow solidification range for 3D printability. The designed compositions are synthesized via high throughput vacuum arc melting. The samples are then characterized using electron microscopy (SEM/EDX), XRD, Vickers microhardness, and nanoindentation experiments. In as-cast state, all samples had BCC phase with dendrites. Homogenization heat treatments are performed at 2000°C to eliminate the dendritic structure after diffusion calculations based on the compositional differences measured in the dendrites. Compression experiments are conducted at high temperatures to compare the initial model predictions and the experimental strength results, which will be presented in detail.
E-14: High Throughput Multi-principal Element Alloy Exploration Using a Novel Composition Gradient Sintering Technique: Brady Bresnahan1; David Poerschke1; 1University of Minnesota
Exploration of multi-principal element alloys (MPEAs) requires a high throughput process to navigate the vast composition space. One such process uses spark plasma sintering (SPS) to introduce a composition gradient along the shortest dimension (5 mm) of a bulk sample. A novel technique was developed to fabricate gradients along the longest dimension of the sample (20 mm), allowing for more compositions in the gradient. The tooling was first validated with binary NiCu and MoNb gradients and was later used to fabricate a Hf gradient in MoNbTaWHf. The resulting gradients were annealed to form solid solutions and characterized by energy dispersive spectroscopy and nanoindentation hardness mapping. The functionally graded MPEAs will allow for high throughput exploration of MPEA composition and surface modification combinations to improve surface properties for aerospace applications. With SPS being a widely applicable densification process, this gradient technique could allow high throughput exploration of other material systems.
E-15: Study on Texture Evolution In Cold Rolled High Entropy Alloy during Annealing: Lalit Kaushik1; Wi-Geol Seo2; Joo-Hee Kang3; Dong-Ik Kim4; Jin-Yoo Suh4; Shi-Hoon Choi2; Jaiveer Singh5; 1Sunchon National University; 2Sunchon National University, Suncheon; 3Korea Institute of Materials Science; 4Korea Institute of Science and Technology; 5Indian Institute of Technology Jodhpur
The annealing texture evolution of cold-rolled high entropy alloy is studied especially focusing on the contribution of annealing twins. The material was cold-rolled to 80% reduction in thickness, and then annealed at 700°C for time varying from 5 min to 1 hour. The annealed specimens were characterized with in-situ transmission Kikuchi diffraction (TKD) technique. The Brass-type texture was developed in 80% cold-rolled specimens. The Brass, S, Goss, and shear texture components decreased as the annealing time increased. Moreover, some new orientations such as the Cube texture component and (φ1=90°,ϕ=30°, φ2=45°) orientation were evolved. The (φ1=90°,ϕ=30°, φ2=45°) orientation was close to the orientation corresponding to the 2nd, 3rd and 4th generations of annealing twins of the Brass texture component while the Cube texture component was close to the orientation corresponding to the 5th generation of annealing twins of the S texture component.
E-16: The Effect of Local Composition on the Initiation Mechanism of Adiabatic Shear Banding in WFeNiMo: Sarah O'Brien1; Matthew Beck1; 1University of Kentucky
Multi-Principal Element Alloys (MPEAs) are a new field in metallurgy. High strain rate plastic deformation, however, has not been explored extensively in MPEAs. Adiabatic shear banding has been observed but not modeled in MPEAs like WFeNiMo. The is debate on the initiation mechanism for adiabatic shear banding being caused by thermal softening or some combination of dynamic recrystallization and recovery. By understanding initiation, the models can be used to predict the conditions in which adiabatic shear banding would occur. The effect of shifting the local composition on initiation mechanism of adiabatic shear banding have not been explore yet. Therefore, an atomistic approach will be taken to investigate the initiation mechanism of WFeNiMo’s adiabatic shear banding at a range of different compositions based on experimental concentrations. This would allow for better prediction of initiation sites for shear banding in WFeNiMo and its subsequent self-sharpening property.