High Entropy Alloys IX: Structures and Modeling : Structures and Characterization 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

Wednesday 8:30 AM
March 17, 2021
Room: RM 9
Location: TMS2021 Virtual

Session Chair: James Morris, Ames Laboratory; Yang Ren, Argonne National Laboratory


8:30 AM  Invited
Predicting High Entropy Alloy Behavior: What We Can Learn from Non-empirical Approaches: James Morris1; 1Ames Laboratory
    The challenges of predicting novel alloy compositions from purely theoretical standpoints remains a challenge, particularly for compositionally complex materials. We review several approaches, from the point of view of using first-principles calculations, and describe successes and remaining challenges from several approaches, in light of existing experimental data. Of particular interest are heuristic approaches that provide prediction of single-phase compositions, more rigorous approaches that tackle the thermodynamics from a more fundamental point of view, and simulation approaches that provide further insight into the behaviors. We examine the strengths and weaknesses of each approach, to indicate directions where these may be utilized and improved upon. Of particular interest is moving beyond “which composition may form a solid solution,” to recognizing the importance of underlying thermodynamic realities that affect the temperature- and composition-dependent transformations of these materials.

8:50 AM  Invited
Role of Local Chemical Order in Orientation Relationship Determination in an Al0.3CoCrFeNi High Entropy Alloys: Elaf Anber1; Daniel Foley1; Diana Farkas2; Peter Liaw3; Mitra Taheri1; 1Johns Hopkins University; 2Virginia Tech; 3The University of Tennessee
    High entropy alloys (HEAs) have attracted the major interest due to their novel mechanical and structural properties. Local chemical ordering (LCO) plays an important role in determining thermal and electrical conductivity of solid solutions, diffusion, and passivity of alloys containing elements that are electrochemically active. Here, we examined the role of LCO on the OR of BCC precipitates in annealed Al0.3CoCrFeNi via using in-situ and ex-situ TEM heating techniques, where we report a new BCC-ORs due to local chemical fluctuations. These studies were coupled with Extended Electron Energy Loss Fine Structure (EXELFS) and Energy-dispersive X-ray spectroscopy (EDS). Additional insight is obtained from molecular dynamics atomistic simulations that examine the various possible orientation relationships and interface dislocations for the B2 precipitates in these Al containing HEA’S. Overall, the LCO associated with ORs offers new opportunities to tune properties, enabling a more predictive view of phase transformation in this class of alloys.

9:10 AM  
Microstructure and Mechanical Properties of a Dual Phase Transformation Induced Plasticity Fe-Mn-Co-Cr High Entropy Alloy: Afm Monowar Hossain1; Rajiv Mishra2; Nilesh Kumar1; 1University of Alabama Tuscaloosa; 2University of North Texas
    High entropy alloys (HEAs), a new class of metallic materials with more than one principal element, are being investigated for a broad range of potential applications. In this study, the microstructure and mechanical properties were examined of a transformation-induced plasticity dual-phase HEA Fe50Mn30Co10Cr10 (at.%) using microstructural and mechanical properties characterization tools including digital image correlation (DIC) and in-situ SEM tensile tester. The elastic behavior, strength, and ductility were determined from tensile test results. The Young’s modulus, strain distribution, and localized strain values in the gage length were evaluated from the DIC data. The gage section of the tensile specimens was analyzed to understand deformation mechanism(s). The localized strains in the gage section were found to be inhomogeneous. An in-depth discussion of deformation mechanism(s) will be presented based on the analysis of DIC and in-situ tensile test data.