A molecular dynamics study on the Mie-Grüneisen equation-of-state and high strain-rate behavior of equiatomic CoCrFeMnNi

Abstract

Through atomistic simulations, we uncover the dynamic properties of the Cantor alloy under shock-loading conditions and characterize its equation-of-state over a wide range of densities and pressures along with spall strength at ultra-high strain rates. Simulation results reveal the role of local phase transformations during the development of the shock wave on the alloy's high spall strength. The simulated shock Hugoniot results are in remarkable agreement with experimental data, validating the predictability of the model. These mechanistic insights along with the quantification of dynamical properties can drive further advancements in various applications of this class of alloys under extreme environments.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

The spall behavior of Cantor alloys is mediated by a strain-rate dependent, reversible FCC-to-HCP phase transition mechanism during shock loading endowing them with high spall strength compared to conventional alloys.

Keywords:

• Spall
• equation of state
• high entropy alloys
• phase transformation
• atomistic simulations

Acknowledgments

This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This article has been authored by an employee of National Technology and Engineering Solutions of Sandia, LLC under Contract No. DE-NA0003525 with the U.S. Department of Energy (DOE). The employee owns all right, title and interest in and to the article and is solely responsible for its contents. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this article or allow others to do so, for United States Government purposes. The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan https://www.energy.gov/downloads/doe-public-access-plan. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Data availability

The data that support the findings of this study are available from the authors upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statement novelty

We characterize and quantify multiple fundamental properties of Cantor alloys, including equations-of-state (EOS), constitutive relationships, and dynamic deformation mechanisms using atomistic simulations. These properties describe the materials behavior under changes in pressure, volume, entropy and temperature, making them fundamental to the design of novel materials that share similar structural and chemical features capable of withstanding extreme mechanical environments. The spall behavior of Cantor alloys is mediated by a strain-rate dependent, reversible FCC-to-HCP phase transition mechanism during shock loading endowing them with high spall strength compared to conventional alloys. These mechanistic understandings provide valuable insights into the factors that affect spall behavior in a wide range of alloys that share similar crystallographic structure and chemical features. This knowledge can be used to design new alloys with improved spall resistance for a variety of applications.

Additional information

Funding

This work was supported by the National Nuclear Security Administration (grant number DE-NA0003525).