Advances in Multi-Principal Element Alloys II: Alloy Development and Application I
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Alloy Phases Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Yang Ming Chiao Tung University; Jennifer Carter, Case Western Reserve University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; James Brechtl, Oak Ridge National Laboratory; Gongyao Wang, Globus Medical
Monday 8:30 AM
March 20, 2023
Room: Aqua D
Location: Hilton
Session Chair: Peter Liaw, The University of Tennesee; Carl Koch, North Carolina State University
8:30 AM Keynote
Nanostructured Multi-principal Ellement Alloys: A Review: Carl Koch1; 1North Carolina State University
This talk will review research on nanostructured multi-principal element alloys (NM-PEAs). This topic combines two popular research areas in materials science - 1. nanostructured materials, and 2. multi-principal element alloys. This topic has been reviewed in the literature by several authors including the speaker(Koch, 2017) and Hache’ et al. (2020). Most processing methods for NM-PEAs have involved severe plastic deformation ( especially mechanical alloying of powders, or to a lesser extent, high pressure torsion). Limited studies of NM-PEAs made by magnetron sputtering, and most recently, electrodeposition, will be described. This talk will emphasize enhanced properties that NM-PEAs may provide. These include mechanical properties (hardness and strength), wear resistance, thermal and phase stability, corrosion resistance, and selected functional properties. The alloys to be discussed include the most studied 3d element alloys, refractory metal alloys, and a low density alloy.
9:00 AM Keynote
Exceptional Fracture Toughness of CrCoNi-based Alloys Close to Liquid Helium Temperatures: Robert Ritchie1; Dong Liu2; Qin Yu3; Saurabh Kabra4; Madelyn Payne5; Ruopeng Zhang5; Flynn Walsh5; Bernd Gludovatz6; Mark Asta5; Andrew Minor5; Easo George7; Punit Kumar8; 1University of California, Berkeley
; 2Bristol University; 3Lawrence Berkeley Natonal Laboratory; 4Rutherford Appleton Laboratory; 5University of California, Berkeley; 6University of New South Wales; 7Oak Ridge National Laboratory; 8Lawrence Berkeley National Laboratory
CrCoNi-based medium/high-entropy alloys show outstanding strength, ductility and toughness, especially at cryogenic temperatures. Here we examine their fracture toughness at 20 K. At a flow stress ~1.5 GPa, exceptionally high crack-initiation KJIc toughnesses were found, respectively 235 and 415 MPa√m for CrMnFeCoNi and CrCoNi, with the CrCoNi alloy displaying a crack-growth toughness Kss exceeding 540 MPa√m, which we believe is the highest toughness ever reported. Characterization of the crack-tip regions reveal deformation structures at 20 K that involve heterogeneous nucleation, but restricted growth, of stacking faults and fine nano-twins, together with limited transformation to epsilon-martensite. The extreme fracture resistance results from a progression of deformation mechanisms - dislocation glide, stacking-fault formation, nano-twinning and eventually in situ phase transformation - that generates prolonged strain hardening to elevate strength and ductility (by delaying plastic instability), resulting in exceptional toughness.
9:30 AM Invited
High Throughput Design and Synthesis of MPEAs: Unexpected Discoveries: Mitra Taheri1; 1Johns Hopkins University
Multiprincipal element alloy (or high entropy alloy) compositional space is considered to be as large as billions of alloys- an immeasurable or at least inaccessible number. At the same time, findings to date coupled with critical advancements in theory have shown the promise of this compositional space to find alloys that replace our current state of the art systems, pushing boundaries of temperature stability, radiation tolerance, corrosion resistance, and even functional properties. This talk discusses high throughput approaches using combinatorial film and bulk methodologies, coupled with machine learning, to tackle difficult-to-assess alloys, such as refractory alloys as well as magnetic systems. We show the value in compositional sweeps to uncover novel stoichiometries with improved functional and environmental properties.
9:50 AM Invited
High Entropy Alloys and NSF: Jonathan Madison1; 1National Science Foundation
Across the National Science Foundation, High Entropy Alloys (HEAs) are gaining an increasing amount of attention and focus. While they represent a fundamental shift in alloying strategy and property optimization, they yet require significant investment to realize their full potential. In this talk, we will showcase a few examples of recent HEA research projects funded by the Division of Materials Research and in particular, the Metals and Metallic Nanostructures Program. Funding mechanisms used to facilitate these efforts will be highlighted and a few notable and recent funding opportunities along with their requirements, application windows and focus areas will also be shared. Lastly, some closing thoughts with a view toward broader perspectives on NSF, it’s Directorate for Technology, Innovation and Partnerships as well as existing programs such as DMREF and MRSEC will be presented toward a discussion of the Materials Genome Initiative.
10:10 AM Break
10:30 AM Invited
Design and Development of Refractory High-entropy Alloys via An Experimentally Driven High-throughput Approach: Chanho Lee1; Dongyue Xie1; Benjamin Derby1; Jon Baldwin1; Christopher Tandoc2; Osman Atwani1; Yong-Jie Hu2; Nan Li1; Saryu Fensin1; 1Los Alamos National Laboratory; 2Drexel University
High-entropy alloy (HEA) design strategies have been limited to theoretical/computational approaches due to their compositional complexity and extremely large compositional parameter space. In this work, we developed an experimentally driven, high-throughput, HEA design approach using a physical vapor deposition (PVD) technique and coupled it with nanomechanical testing to accelerate material design for structural applications. The PVD technique enabled the formation of a compositional gradient across a thin-film sample. Specifically, a 10 cm wafer was used to manufacture a continuous set of 80 HEA compositions within the Nb-Ti-V-Zr family using a single deposition cycle. By applying the solid-solution strengthening theory and developed machine-learning approaches, the strength and ductility of these HEA compositions were quantitatively determined/predicted and then experimentally verified by nano-indentation hardness test. Consequently, 7 refractory HEA compositions were successfully down-selected based on optimized strength and ductility predictions.
10:50 AM Invited
Accelerated Design of Cost-Competitive FCC High Entropy Alloys Superior to IN625: Kenneth Smith1; John Sharon1; Ryan Deacon1; Soumalya Sarkar1; Shunli Shang2; Zongrui Pei3; Michael Gao3; 1Raytheon Technologies Research Center; 2Pennsylvania State University; 3National Energy Technology Laboratory
This work aims to design cost-competitive FCC-based high entropy alloys (HEAs) with significantly improved mechanical and oxidation properties than IN625. As the unexplored composition space in HEAs is huge, an efficient and reliable computational approach is hence taken to accelerate alloy discovery. This approach integrates multi-fidelity machine learning, CALPHAD, density functional theory (DFT), and empirical models to quickly identify cost-effective HEA compositions. A series of different objectives and constraints applied to guide selection of alloy candidates. Selected candidates are fabricated and subjected to thermal and mechanical testing along with characterizing the thermally grown oxides. DFT-based calculations are carried out to predict atomic structure, temperature-dependent elastic properties, stable and unstable stacking faults energies of selected HEAs. Effects of dilute solute elements on diffusion coefficients of interstitial and substitutional elements are also predicted by transition state theory. Strategies in accelerating alloy design with improved strength and oxidation resistance will be discussed.
11:10 AM Invited
High-Throughput Design of Refractory Multi-Principal Element Alloys: Katharine Padilla1; Zhaohan Zhang1; Rohan Mishra1; Katharine Flores1; 1Washington University in St. Louis
The design of high entropy alloys often focuses on identifying near-equiatomic solid solution alloys; expanding these to include multiphase microstructures offers the opportunity to further enhance and control properties. Designing such multiphase, multi-principal element alloys (MPEAs) requires the ability to efficiently survey compositional space for phases and microstructures of interest using integrated experimental and computational methods. Here, we build on prior studies of the Nb-V-Zr system, which forms a BCC solid solution phase and two Laves phases. Applying a convex hull analysis, we predict the effect of Ti, Ta, and Mo additions on the stability of the BCC phase as a function of temperature and composition. The predicted structures are compared with the microstructures observed in compositional libraries prepared using a high-throughput, laser deposition-based synthesis method. This work provides guidelines for predicting compositional effects on microstructure and properties, which will accelerate the design of MPEAs for high-temperature applications.
11:30 AM Invited
Additive Manufacturing of Compositionally Complex Metal Alloys with Engineered Microstructures: Wen Chen1; 1University of Massachusetts-Amherst
The increasing demands for materials require increasingly complex compositions and microstructures, which meanwhile bring grand challenges in processing and understanding of microstructure-property relationships in these materials. To overcome these challenges, I will present some recent work in our group on fabrication of compositionally complex metal alloys by additive manufacturing, which enables multiscale engineering of highly heterogeneous microstructures with excellent mechanical properties. Specifically, I will discuss the potential of using laser additive manufacturing and direct ink writing based 3D printing techniques to process compositionally complex metal alloys such as metallic glass composites and high-entropy alloys towards superior mechanical performance.
11:50 AM Invited
Tailoring Microstructure of Refractory High Entropy Superalloys through Semi-quantitative Miscibility Gap: Sangjun Kim1; Jiyoung Kim1; Jae Kwon Kim1; Kook Noh Yoon1; Hyun Seok Oh2; Eun Soo Park1; 1Seoul National University; 2Massachusetts Institute of Technology
For a few decades, there have been extensive investments to develop alternative materials of Ni-based superalloys for high-temperature applications. Recently, a new class of alloys called refractory high-entropy superalloys (RHSAs) has attracted significant attention due to their superior mechanical properties. However, there are many issues that need to be resolved, such as optimal phase selection between ordered and disordered BCC phases, precipitation control of unwanted compounds, optimization of mechanical properties, etc. In the present study, we propose how to tailor the microstructure of RHSAs through a bulk combinatorial approach in the TiZrNbTaAl quinary system. By collecting all the results on microstructure and phase transformation, a semi-quantitative miscibility gap was successfully constructed for the (TiZr)-(NbTa)-Al pseudo-ternary system, which can provide an effective guideline for tailoring microstructure of RHSAs like other conventional superalloys. Our study paves the way for the development of promising RHSAs with customized microstructure for ultra-high temperature structural applications.
12:10 PM Invited
Designing Immiscible Medium-entropy Alloys: Hyoung Seop Kim1; Jongun Moon1; 1Pohang University of Science and Technology
A new strategy for designing heterogeneous high-entropy or medium-entropy alloys based on immiscible elements with light-weight and excellent mechanical properties is proposed. As an example, Alx(CuFeMn)100-x (x = 0, 7.5, and 15 at%) alloys were developed by utilizing the immiscible nature of Cu-Fe alloys. The microstructures of the alloys show phase separation into Cu-rich and Fe-rich regions, and the addition of Al transforms the crystal structure from dual face-centered cubic to face-centered cubic and body-centered cubic. Phase separation of the microstructure into two domains enables further dissolution of Al into the matrix. The alloys exhibit high strength because of solid solution strengthening and hetero-deformation induced strengthening caused by heterogeneous microstructures. The presence of nano-scale twins and essential partially recrystallized microstructures also enhances the strength of the alloys. This new type of medium-entropy alloys is expected to expand the design window in physical metallurgy.