High Entropy Alloys IX: Alloy Development and Properties: Alloy Development and Application II
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Chiao Tung University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; Gongyao Wang, Globus Medical
Monday 2:00 PM
March 15, 2021
Room: RM 10
Location: TMS2021 Virtual
Session Chair: Veerle Keppens, Univ of Tennessee; Ke An, Oak Ridge National Laboratory
2:00 PM Invited
Synthesis and Mechanical Properties of High Entropy Oxide Spinels: Veerle Keppens1; Brianna Musico1; Kurt Sickafus1; Quinton Wright1; Joshua Smith1; 1University of Tennessee
Reports on the unique properties achieved with HEAs, including improved mechanical properties, has motivated the application of the multi-component approach to oxide materials, expanding the available compositional space and providing greater flexibility to meet the demands of today’s advanced materials. We have applied this methodology to oxides with the spinel structure, resulting in the synthesis of several polycrystalline high entropy spinels. Resonant Ultrasound Spectroscopy (RUS) has been used to evaluate the elastic behavior of dense polycrystalline pellets sample, allowing for a comparison of the mechanical properties of the multicomponent oxides to those of traditional spinels.
2:25 PM Invited
Phase Formation, Structure Modulation and Property Optimization of High Entropy Alloys, Composites and Glasses: Jurgen Eckert1; 1Erich Schmid Institute of Materials Science
This talk explores the structural diversity that can be achieved in high entropy alloys, multiphase composites and metallic glasses developed through a combination of concepts for designing chemically complex alloys and metallic glasses using rapid quenching and annealing for tuning phase formation and microstructure development. The role of phase transformation upon heating or loading will be critically assessed with respect to structural stability and mechanical behavior. Examples for changes in deformation mechanism, e.g. from crack-controlled to dislocation-dominated deformation or cooperative deformation of shear bands and interfacial sliding, will be discussed and analyzed as ways to control both strength and ductility in a wide range. Besides, also examples for tuning the magnetic properties via composition and process control will be given, attempting to derive guidelines for how to tune the microstructure and properties of non-equiatomic chemically complex alloys with optimized properties.
2:50 PM Invited
High Etropy Alloy Design Aided by Neutron Scattering: Ke An1; Rui Feng1; Sichao Fu1; 1Oak Ridge National Laboratory
High entropy alloys (HEA) attract great attention because of their superior physical and mechanical properties, by compositional optimization. Predictive alloy design through theoretical modeling faces challenges due to the high microstructural and compositional complexity compared to available databases. A large amount of experimental effort is focused on understanding the complex structure-property relationships via conventional characterizations. Neutron scattering is a bulk average non-destructive material characterization of both morphological and crystallographic structures by probing materials with significant advantages e.g. sensitivity to light elements, transition metals, isotopes, nuclear and magnetic structure ordering, as well as deep penetration with complex sample environments, etc. Materials research of HEAs using neutrons for material synthesis, lattice structure, phase transition, physical properties and deformation mechanisms at extreme environments has become popular recently. We show by practical examples that neutron aids the alloy design in understanding material properties, providing predictive model validations and accelerating next generation structural material discoveries.
3:15 PM Invited
Combining Elemental and Microstructure Heterogeneities in High-entropy Alloys to Enhance Radiation Resistance: Yanwen Zhang1; Miguel L. Crespillo2; Walker L. Boldman2; Philip D. Rack2; Hongbin Bei1; Yongqin Chang3; Li Jiang4; Lumin Wang4; William J. Weber2; 1Oak Ridge National Laboratory; 2University of Tennessee; 3University of Science and Technology Beijing; 4University of Michigan
Understanding critical roles of elemental and microstructure heterogeneities in high-entropy alloys (HEAs), as well as their response to radiation may lead to transformative opportunities in material research. In HEAs, the random arrangement of multiple elemental species creates solid-solution heterogeneities that lead to unique non-periodic electronic structure and energy landscapes. Such chemical complexity resulting from the elemental heterogeneities allow us to tailor defect production and damage evolution in radiation environments. Recent research beyond properties that are intrinsic to HEAs will be discussed, including alloying low concentration of solute elements in the crystal form, high-density grain boundaries and interfaces in the nanocrystalline form, and oxide dispersion strengthened HEAs. The approach by combining chemical complexity with structural complexity is shown to have distinctive improvements in modifying defect dynamics, suppressing extended defect growth, and thus achieving substantially improved radiation resistance.This work was supported by EDDE EFRC, funded by the US DOE/BES.
3:40 PM
Distinctive Room Temperature Deformation Behavior in Plastic BCC Refractory High-entropy Alloys: Chanho Lee1; Gian Song2; Michael Gao3; Wei Chen4; Ke An5; Peter Liaw1; 1University of Tennessee; 2Kongju National University; 3National Energy Technology Laboratory/Leidos Research Support Team; 4Illinois Institute of Technology; 5Oak Ridge National Laboratory
The deformation behaviors for NbTaTiV and NbTaTiVZr high-entropy alloys (HEAs) have been investigated to demonstrate the unique plastic-deformation behavior in plastic body-centered-cubic (BCC)-structured refractory HEAs via the in-depth in-situ neutron study. Both BCC refractory HEAs indicated the simple solid-solution microstructure and excellent single BCC phase stability without the stress-induced phase formation/transformation during plastic deformation. The relatively-brittle NbTaTiVZr HEA presents the typical elastic and plastic deformation behavior of the BCC-structured alloy, exhibiting the elastic and plastic anisotropic feature with the significant load transfer from {110} to {200}-oriented grains during plastic deformation. However, the NbTaTiV HEA shows the elastic isotropic and reduced plastic anisotropic deformation behaviors. These unusual plastic deformation in the NbTaTiV HEA leads to the evenly-sharing applied stresses among the differently-oriented grains rather than stress concentration on particular-oriented grains during plastic deformation. Therefore, the homogenous load-transfer between differently-oriented grains could result in the excellent plasticity (ductility) in BCC-structured refractory HEAs.
4:00 PM
Metastability and Phase Selection in High Entropy Alloys: Sebastian Kube1; Pamela Banner1; Sungwoo Sohn1; David Uhl2; Amit Datye1; Suchismita Sarker3; Apurva Mehta3; Jan Schroers1; 1Yale University; 2Southern Connecticut State University; 3SLAC National Accelerator Laboratory
High Entropy Alloys (HEAs) span a vast composition space, across which single-phase solid solutions (SPSS) can form at varying degrees of metastability. We argue that metastable SPSS form through polymorphic solidification upon rapid cooling. To quantify a HEA’s metastability, we propose the critical cooling rate of SPSS formation RCSPSS, which is analogous to RCGlass for glass formation. On this unified basis, we compare multicomponent alloys by their metastability and tendency to form SPSS or glasses, which is determined by the underlying atomic dispersity. We explore large numbers of alloys in this space using combinatorial co-sputtering and high-throughput EDX and synchrotron XRD. Our new data set comprises ~10,000 ternary and quinary compositions based on 20 different elements. Amongst SPSS, we reveal a BCC preference effect: The BCC structure becomes increasingly favorable with increasing atomic size difference, because of its ability to accommodate atoms of various sizes more efficiently than FCC.