High Entropy Materials: Concentrated Solid Solution, Intermetallics, Ceramics, Functional Materials and Beyond: Materials Discovery and Design II
Sponsored by: ACerS Basic Science Division, TMS Alloy Phases Committee
Program Organizers: Xingbo Liu, West Virginia University; Michael Gao, National Energy Technology Laboratory; Peter Liaw, University of Tennessee; Jian Luo, University of California, San Diego; Yiquan Wu, Alfred University; Yu Zhong, Worcester Polytechnic Institute
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 33
Location: MS&T Virtual
Session Chair: Ganesh Balasubramanian, Lehigh University; Hyoung Seop Kim, Pohang University of Science and Technology
2:00 PM Invited
Investigating Multi-principal-element Alloys (MPEAs) at Larger Scales: From Melt Processing to New Design Approaches: Martin Detrois1; Kyle Rozman1; Michael Gao1; Paul Jablonski1; Jeffrey Hawk1; 1National Energy Technology Laboratory
While a large number of recent investigations on high-entropy alloys (HEAs) or multi-principal-element alloys (MPEAs) focus on high throughput characterization and testing, there is a growing need to assess the potential at using this class of alloys in structural applications. Typical melt processing techniques using vacuum induction melting (VIM) were employed to produce 7-10 kg ingots that can be tested using ASTM standards for tension and creep after being forged and hot rolled into plates. Creep results from the cast and wrought HEAs were compared to commercial steels and superalloys and discussed relative to the new design approaches. The alloys designed and tested in house ranged from traditional HEAs to MPEAs and high-entropy superalloys and revealed the importance of good fabricability alongside properties and cost considerations. Finally, challenges associated with the typical industrial melt processing technique VIM followed by electroslag remelting (ESR) will be discussed using ~75 kg HEA ingots.
2:20 PM Invited
The Use of CALPHAD Based Tools to Simulate Applications of HEA Materials: Huahai Mao1; Lina Kjellqvist1; Paul Mason2; Qing Chen2; 1Thermo-Calc Software AB; 2Thermo-Calc Software Inc.
Modeling HEAs using CALPHAD presents unique challenges compared with other alloy systems due to the lack of a single principle element. Here we describe the approach taken in developing the TCHEA thermodynamic database, which contains 26 elements, where almost all underlying binary and over 400 ternary systems have been critically evaluated to capture the composition and temperature dependence.Examples will be given of i) the development of cemented carbide cutting-tools with HEA as the binder phase demonstrating the design strategy in terms of thermodynamic equilibrium between HEA and carbides; ii) studying the oxidation behavior of HEAs and the corresponding (high entropy) oxide products such as those with halite or spinel structures using a combination of compatible databases TCHEA with TCOX; iii) the coupling of a thermodynamic database with a compatible kinetic database to simulate the precipitation of intermetallic phases from HEAs during annealing.
2:40 PM Invited
Control of Discontinuous and Continuous Precipitation of Gamma-prime Strengthened High-entropy Alloys: Lei Fan1; Zengbao Jiao1; 1The Hong Kong Polytechnic University
Precipitation of coherent L12-type gamma-prime precipitates has been recognized as a powerful method to strengthen fcc high-entropy alloys (HEAs) at room and elevated temperatures. Continuous precipitates are primarily responsible for precipitation hardening, whereas discontinuous precipitates contribute a limited hardening capability and often crack grain boundaries. In this talk, we show that minor alloying additions can have a significant effect on the precipitation behavior and mechanical properties of HEAs. The alloying additions not only suppress the discontinuous L12 precipitation through grain boundary segregation but also promote the continuous L12 precipitation through solute partitioning, which leads to a uniform distribution of L12 nanoparticles throughout the matrix, thereby enhancing the mechanical properties of the HEAs. The mechanisms for the suppression of discontinuous precipitation and promotion of continuous precipitation are discussed.
3:00 PM
Machine Learning and Data Analytics for Identification of HEA Compositions and Processing Conditions Resulting in Enhanced Fatigue Resistance: Xuesong Fan1; Baldur Steingrimsson2; Orlando Rios3; Anand Kulkarni4; Duckbong Kim5; Peter Liaw; 1University of Tennessee; 2Imagars LLC; 3Oak Ridge National Laboratory; 4Siemens Corporation; 5Tennessee Tech University
This presentation outlines an innovative approach to application of machine learning and data analytics, aimed at accelerating the identification of high-entropy alloy (HEA) compositions and process conditions resulting in attractive fatigue resistance. We present general methodology for predicting the fatigue resistance of HEAs, one capable of accounting for physics-based dependencies. We show that HEAs generally exhibit fatigue resistance superior to that of conventional alloys. For a given composition, we indicate, through application of data analytics, that the fatigue resistance of HEAs seems primarily correlated with the ultimate tensile strength (UTS), followed by the defect properties, grain size, and process parameters. Hence, given the multiple sources that impact the fatigue resistance, we note that accurate prediction of the fatigue resistance requires knowledge not only of the UTS, but also of defect properties, grain size, and process conditions. We demonstrate consistency of our predictions with empirical rules and experimental findings.
3:20 PM
Using alloy phase diagrams to predict formation of high-entropy alloy phases: Jie Qi1; Mark Wischhusen2; Samuel Inman2; John Scully2; Sean Agnew2; S. Poon1; 1Department of Physics, University of Virginia; 2Department of Materials Science and Engineering, University of Virginia
A refined method for High Entropy Alloy (HEA) phase prediction is essential but challenging in accelerating the discovery of high-performance HEAs. To date, only a very limited portion of the vast HEA compositional space has been explored. In this talk, we will present a HEA phase prediction method that mines useful information from binary phase diagrams, which leads to the use of unconventional machine learning (ML) model features formulated based on the phase field regions appropriately defined by composition and temperature. The success rate of this method is near 85 % in predicting the formation of single FCC, BCC, and HCP phases as well as composite phases that contain a limited number of intermetallic phases. The method has been experimentally validated. Further development of the ML model enables prediction of a broader range of HEA composites.
3:40 PM Cancelled
Electrodepositionof Nanocrystalline Medium and High-entropy Alloys: Michel Haché1; Yu Zou1; 1University of Toronto
Compared with typical nanocrystalline (nc) metals and alloys, nc high-entropy alloys (HEAs) exhibit exceptional mechanical properties with satisfied thermal stability. Typical methods for producing nanocrystalline HEAs usually requires severe mechanical deformation. Upon heating, grain size grows rapidly, limiting their applications at elevated temperatures. Here, we investigate a series of equiatomic binary NiCo, ternary NiCoFe, NiFeCr, and quaternary NiCoFeCu nanocrystalline alloys, produced using electrodeposition. The alloys were subsequently processed with heat treatment at temperatures in the range 573-823 K. Nanoindentation were applied to identify the temperature dependency of mechanical properties. Our study demonstrates a scalable method for producing high-strength and thermally stable HEAs.