Computational modeling of high-entropy alloys: Structures, thermodynamics and elasticity
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Computational modeling of high-entropy alloys: Structures, thermodynamics and elasticity Michael C. Gaoa) National Energy Technology Laboratory, Albany, Oregon 97321, USA; and AECOM, Albany, Oregon 97321, USA
Pan Gao Department of Electrical and Computer Engineering, Tennessee State University, Nashville, Tennessee 37209, USA
Jeffrey A. Hawk National Energy Technology Laboratory, Albany, Oregon 97321, USA
Lizhi Ouyang Department of Physics and Astronomy, Tennessee State University, Nashville, Tennessee 37209, USA
David E. Alman National Energy Technology Laboratory, Albany, Oregon 97321, USA
Mike Widom Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA (Received 22 May 2017; accepted 15 August 2017)
This article provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi . CoOsReRu . MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if the same crystal structure is used for the elements and the alloy. The deviation in the calculated elastic properties from ROM for select alloys is small but is susceptible to the choice used for the structures of pure components.
I. INTRODUCTION 1
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Since Yeh and Cantor independently reported their research on high-entropy alloys (HEAs) or equimolar multicomponent alloys in 2004, HEAs have attracted considerable interest from the scientific community, both in terms of developing a fundamental scientific understanding and potential technological applications.3–5 However, to date, a variety of important questions still remain: In particular, what factors govern the formation of single-phase solid solution HEAs? What are the total number of possible single-phase equimolar HEA alloys with the face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP) structures, respectively? For each crystal structure type, what is the maximum number of components that a single-phase
Contributing Editor: Susan B. Sinnott a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.366
HEA can possibly dissolve at high temperatures? How can the thermodynamic properties of single-phase HEAs be accurately predicted, given the assumed disordered atomic structures? What other entropy sources are possible, given the fact that the definition of HEAs by Yeh is based on the ideal configurational entropy? How can the elastic properties of single-phase HEAs be reliably calculated and how do they compare with their pure comp
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